Profinite group: Difference between revisions

From formulasearchengine
Jump to navigation Jump to search
en>TakuyaMurata
 
en>Epicgenius
Reverted 1 good faith edit by 130.75.46.14 using STiki (Mistake? Report it.)
Line 1: Line 1:
== New Balance 574  sammanfattar det bäst ==
[[File:Railroad-Tracks-Perspective.jpg|thumb|right|Parallel lines intersect in the [[vanishing point]] at infinity.]]
In [[mathematics]], a '''projective plane''' is a geometric structure that extends the concept of a [[plane (geometry)|plane]]. In the ordinary Euclidean plane, two lines typically intersect in a single point, but there are some pairs of lines (namely, parallel lines) that do not intersect. A projective plane can be thought of as an ordinary plane equipped with additional "points at infinity" where parallel lines intersect. Thus ''any'' two lines in a projective plane intersect in one and only one point.


Ingen av sidorna ska ha student namn på den. Den dokumenterar den kreativa processen från frö [http://www.hush.se/dotnet/backup/jolagard.asp New Balance 574] till stora skärmen och därför man inte behöver vara en die hard fan att njuta av, helt enkelt någon som är intellektuellt curious.A fantastisk insats om sex fantastiska män (och det incomprable 'Kvinna Python' Carol [http://www.barnensdagovik.se/logs/images/framework.php Beats By Dre Solo] Cleveland) . <br><br>Primitiva förhållanden bör förväntas när någon hjälper någon efter en katastrof. För mer avancerade studenter, kan du låta dem arbeta självständigt samtidigt som mellanliggande och börjar eleverna arbetar i grupp. Helst de kommer [http://www.barnensdagovik.se/logs/images/framework.php Beats By Dre] att avgöra följande. <br><br>Storbritannien är att ge Filippinerna mer än 6 miljoner i stöd för att hjälpa landet att återhämta sig från den förödande super tyfon, som befaras ha dödat mer än 10.000 personer. Bränn aldrig broarna bakom dig. De arbetade för att de förstärkte den underliggande integriteten i huden. <br><br>Dessutom finns det också några filer av faktiska data fångas med hjälp av NI 5734 adaptermodul som kan användas för en mer realistisk simulation.The övergripande flytande och fasta punkten simulering kan hittas i NI 5734 DDC med 4 [Värd Behavioral] VI . <br><br>Viktväktarna gruppledare, för i pris Chopper Plaza i Schenectady, sammanfattar det bäst: 'Om det växer eller har en mor, kan du äta den.' Alla Team Ledare är medlemmar och måste behålla sin målvikt ge eller ta några pounds de är bara människor.. När beskriver länk använda SEO principer för [http://www.barnensdagovik.se/logs/casio.php Nike Jordan Skor] att vinna advantage.Sitemap generation hjälper bolag att se alla sidor på din webbplats utan att behöva leta efter dem. <br><br>Räkningsbara substantiv är saker med mängder som du ser med dina ögon. På den tiden verkade det vara många. Jag talat med företag som använder minst 8 olika sociala medier tillämpningar för att stödja CRM och detta ISN sällsynt! Det finns inte en allt i ett program på marknaden just nu. <br><br>I engelska gymnasieskolor, har sponsrade akademier förbättrats snabbare än andra statligt finansierade skolor och i en snabbare takt än andra typer av skolor i trafik under liknande omständigheter. Sälja andras saker!. Visualisering är nyckeln till att programmera ditt sinne för framgång. <br><br>Det kräver vår uppmärksamhet och som webb marknadsförare vi ignorera det på vårt företags risk.. Använd historia siffror eller förhållande som din vägledning.. Med andra ord, se om hon är villig att dejta dig och ge en 'romantisk' relation en chans att växa.. <br><br>Jag kan lova er, är inget mer imponerande att en potentiell långivare än att begära finansiella data och få den levererad innan du kan få av telefonen!. Naturligtvis kommer frame tider varierar beroende på vad som händer i spelet.. Med mer övning lär du dig att formulera saker, hur man skapar fulla karaktärer med verkliga brister och riktiga talanger.
[[Perspective (graphical)#Renaissance: Mathematical basis|Renaissance]] artists, in developing the techniques of drawing in [[Perspective (graphical)|perspective]], laid the groundwork for this mathematical topic. The archetypical example is the [[real projective plane]], also known as the '''Extended Euclidean Plane'''. This example, in slightly different guises, is important in [[algebraic geometry]], [[topology]] and [[projective geometry]] where it may be denoted variously by PG(2,'''R'''), '''RP'''<sup>2</sup>, or ''P''<sub>2</sub>('''R''') among other notations. There are many other projective planes, both infinite, such as the [[complex projective plane]], and finite, such as the [[Fano plane]].
相关的主题文章:
<ul>
 
  <li>[http://www.0351china.com/bbs/forum.php?mod=viewthread&tid=94160&fromuid=24651 http://www.0351china.com/bbs/forum.php?mod=viewthread&tid=94160&fromuid=24651]</li>
 
  <li>[http://playmond.com/activity/p/48158/ http://playmond.com/activity/p/48158/]</li>
 
  <li>[http://364088.cn/news/html/?190372.html http://364088.cn/news/html/?190372.html]</li>
 
  <li>[http://www.tc139.cn/news/html/?229816.html http://www.tc139.cn/news/html/?229816.html]</li>
 
</ul>


== Air Max 1 Dam Använd inte marknadsföring slagord ==
A projective plane is a 2-dimensional [[projective space]], but not all projective planes can be embedded in 3-dimensional projective spaces. The embedding property is a consequence of a result known as [[Desargues' theorem]].


Inte lösningen.. Det andra alternativet skulle vara att attackera en konvoj av bränslestavar på väg till lång sikt, 1000 år, lagring, men dessa är sällan flyttas, då de är de inte flyttas i bulk och kan inte göras till atombomber bara smutsiga bomber. <br><br>De flesta av oss don trivs att ge upp säkerheten i en stadig inkomst, åtminstone inte i början.. De kommer att visa dessa uttalanden på en kampanjaffisch tillsammans med en bild på sina husdjur, men affischerna ska inte säga vem som äger varje husdjur. <br><br>Den kommer att bestå av en serie steg från maximal säkerhet genom att, vid behov övervakad frigivning i samhället. När det stod klart att [http://www.ovikenost.se/logout/define.asp Air Max 1 Dam] en del att hålla den amerikanska regeringen kör inte skulle passera en deadline avstängning sent måndag kväll, reagerade marknaderna. <br><br>The Montana nätverket för mänskliga rättigheter rapporterar att ledaren för demonstrationen var Allen Goff, den 17 år gamla från Billings, som har fått namnet 'Skaparen av året' av gruppen.. Och medan vanliga stavningar för vanliga ord som inte passar reglerna bör stå som exeptions från regeln, är listan över ord som passar den kategorin, och bör förbli, ganska små. <br><br>Multiplicera är faktiskt den bästa platsen för att kontrollera de mest unika objekt som du inte kan hitta i en fysisk butik eller i gallerior. Utländska transaktionsavgifter. Men jag är inte riktigt vilja dumpa stora [http://www.hush.se/ekonomi/cheap.asp Nike Air Max 90 Rea] pengar i det där just nu (och inte heller har jag en massa extra pengar eftersom jag donera så mycket till staten). <br><br>Vår lyckliga vinnare kommer att bo i en super chic Juniorsvit med havsutsikt, så du kan smutta på en cocktail eller två samtidigt med utsikt över den obefläckade vyn.. Men när [http://www.ovikenost.se/logout/define.asp Air Max 1] det dags att äntligen sälja din största investering, många säljare fylld med frågor och tvivel. <br><br>Men jag räkna ut det här som jag går tillsammans och montera in den som jag känner att jag kan. Detta är en av de saker du måste se i person för att uppskatta till fullo.. PCIe begränsad bandbredd innebär att inom GPU kommunikationshastigheter inte kommer att närma sig inom CPU-kommunikationshastigheter inom en snar framtid, så SMP liknande operation är fortfarande lite ledigt, men det bör vara tillräckligt snabb för att tillåta utvecklare att arbeta med nya klasser av problem som var för långsamt utan UVA / GPUDirect.. <br><br>Använd inte marknadsföring slagord, och prata i 3: e person sammanhang. Hon kommer noggrant separat orsak (er glädje i din [http://www.implementa.se/Publications/Viewstar.asp Nike Air Max Rea] prestation) från effekt (vägrar att låta dig låna bilen för att åka till prisutdelningen) med tillräckligt med tid att någon som inte lever genom sitt missbruk aldrig skulle tro anslutningen..
==Definition==
相关的主题文章:
<ul>
 
  <li>[http://www.tc139.cn/news/html/?230761.html http://www.tc139.cn/news/html/?230761.html]</li>
 
  <li>[http://www.tc139.cn/news/html/?230756.html http://www.tc139.cn/news/html/?230756.html]</li>
 
  <li>[http://www.caubbs.com/thread-102264-1-1.html http://www.caubbs.com/thread-102264-1-1.html]</li>
 
  <li>[http://www.juzibuy.com/lt/forum.php?mod=viewthread&tid=841711&extra= http://www.juzibuy.com/lt/forum.php?mod=viewthread&tid=841711&extra=]</li>
 
</ul>


== Air Max Billigt  och så vidare. ==
A '''projective plane''' consists of a set of '''lines''', a set of '''points''', and a relation between points and lines called '''incidence''', having the following properties:<ref>In a more formal version of the definition it is pointed out that the terms ''point, line'' and ''incidence'' are [[primitive notion]]s (undefined terms). This formal viewpoint is needed to understand the concept of [[duality (projective geometry)|duality]] when applied to projective planes.</ref>
<div id="axioms-of-projective-planes">
#Given any two distinct points, there is exactly one line incident with both of them.
#Given any two distinct lines, there is exactly one point incident with both of them.
#There are four points such that no line is incident with more than two of them.
</div>
The second condition means that there are no [[Parallel (geometry)|parallel lines]]. The last condition excludes the so-called '''''degenerate''''' cases (see [[#Degenerate planes|below]]). The term "incidence" is used to emphasize the symmetric nature of the relationship between points and lines. Thus the expression "point ''P'' is incident with line ''l'' " is used instead of either "''P'' is on ''l'' " or "''l'' passes through ''P'' ".


Kraftiga rabatter för tidiga användare. Inne i GPU kisel är Tensilica HiFi EP Audio DSP-kärnor, en strömmande DMA motor, 384Kb delat internminne och en låg latens buss som knyter DSP-kärnor till GPU: s frame buffer och huvudsystemminne. Det pingar din webbsida från fyra orter, så att du kan få en global bild av din webbplats prestanda.. <br><br>Det blir också lättare för dig att marknadsföra dina tjänster som en tränare när du är online.. Istället bära något i en färg och lämna de vita till bruden. En var stor riskobenägna. , här är några av de främsta prioriteringarna [http://www.implementa.se/Publications/Viewstar.asp Air Max Billigt] i min mening: 1. Det bästa med denna strategi är att ganska många artikeln kataloger har hög sida rankas (PR). <br><br>Anledningen till att jag tror att det är därför att se hur president Reagan bröt unionen för flygledare tillbaka i 80-talet, för [http://www.blandaren.se/bilder/knappar/on/aviator.php Ray Ban Clubmaster] vad jag skulle tänka på ett mycket tekniskt jobb. Här koden:. Den lokala pressen kåren gick i strejk för en dag. Mindre [http://www.hush.se/ekonomi/cheap.asp Nike Air Max 90 Rea] vanligt, orsakar salmonella utbrott genom ingen mindre än vår vänliga grannskap dricksvatten.. <br><br>Tja, jag har anpassat att säga för mina egna syften, 'kvalitet och kvantitet'. Bara häromdagen meddelade bolaget uppsägning av användarnas förmåga att gömma sig från Facebook sökningar. Tjugo procent kommer att spendera $ 10.000 till $ 30.000 på sin nästa egendom och 16 procent planerar att spendera mer än $ 30.000.. <br><br>Den brittiska papper fortsätter att få in synpunkter på ett antal föreslagna villkor för överföring av makten, bland annat en roll för den val-kommissionen och gränser för timing, om rösträtten (för att utesluta 16 och 17 åringar) och på antalet frågor som ska ställas. <br><br>Spara skatter är coolt. Först publicerad 23 september, 2012Blur Busters täcker framgångsrika tekniker för minskning och eliminering av rörelseoskärpa på LCD-skärmar i en dator kompatibel och videospel kompatibelt sätt. Det ändrar inte det faktum att AMD är inte så bra för spel. <br><br>Problemet var, att köra generell kod på AMD och NVIDIA GPUs innebar med en annan programmeringsverktygslåda för varje. Men det var alldeles för [http://www.ambumedica.se/bilder/start.asp Hollister Göteborg] lätt, eller hur?. En elev säger ett ord (välj en kategori som resor om du vill begränsa saker) och nästa person måste säga ett ord i samband med det ordet; nästa elev säger ett ord i samband med det ordet, och så vidare. <br><br>Dock började hon sin lärarkarriär för tjugo år sedan som instruktör ESL i vuxenutbildning och fortfarande i första hand definierar sig själv som en ESL lärare. Detta har varit en av Banpu nyckelstrategier som ligger bakom 30 år av stabil tillväxt och utveckling.
==Some examples==
相关的主题文章:
 
<ul>
===The Extended Euclidean Plane===
 
 
  <li>[http://jz.zhisen88.com/news/html/?40509.html http://jz.zhisen88.com/news/html/?40509.html]</li>
To turn the ordinary Euclidean plane into a projective plane proceed as follows:
 
:1. To each class of parallel lines add a single new point. That point is considered incident with each line of the class. Different parallel classes get different points. These points are called ''[[point at infinity|points at infinity]]''.
  <li>[http://www.jankloco.com/activity/p/53324/ http://www.jankloco.com/activity/p/53324/]</li>
:2. Add a new line which is considered incident with all the points at infinity (and only them). This line is called '''the''' [[line at infinity]].
 
 
  <li>[http://poodlehack.com/activity/p/309336/ http://poodlehack.com/activity/p/309336/]</li>
The extended structure is a projective plane and is called the '''Extended Euclidean Plane''' or the [[real projective plane]]. The process outlined above, used to obtain it, is called "projective completion" or ''projectivization''. This plane can also be constructed by starting from '''R'''<sup>3</sup> viewed as a vector space, see [[#Vector space construction|below]].
 
 
  <li>[http://box-man.co.uk/air-max-rea-och-de-flesta-b2bforetag-inte-tror-att-de-kan-vara-gerilla/ http://box-man.co.uk/air-max-rea-och-de-flesta-b2bforetag-inte-tror-att-de-kan-vara-gerilla/]</li>
===Projective Moulton Plane===
 
 
</ul>
The points of the '''Moulton plane''' are the points of the Euclidean plane, with coordinates in the usual way. To create the Moulton plane from the Euclidean plane some of the lines are redefined. That is, some of their point sets will be changed, but other lines will remain unchanged. Redefine all the lines with negative slopes so that they look like "bent" lines, meaning that these lines keep their points with negative x-coordinates, but the rest of their points are replaced with the points of the line with the same y-intercept but twice the slope wherever their x-coordinate is positive.
 
See [[Moulton plane]] for a diagram and the specific formulas. This Moulton plane has parallel classes of lines, and it can be used for projections as in the previous example to obtain the '''Projective Moulton Plane'''. [[Desargues' Theorem]] is not a valid theorem in either the Moulton plane or the Projective Moulton plane.
 
===A finite example===
 
This example has just thirteen points and thirteen lines. We label the points P<sub>1</sub>,...,P<sub>13</sub> and the lines m<sub>1</sub>,...,m<sub>13</sub>. The [[incidence relation]] (which points are on which lines) can be given by the following [[incidence matrix]]. The rows are labelled by the points and the columns are labelled by the lines. A 1 in row i and column j means that the point P<sub>i</sub> is on the line m<sub>j</sub>, while a 0 (which we represent here by a blank cell for ease of reading) means that they are not incident. The matrix is in Paige-Wexler normal form.
:::{| class="wikitable"
|-
! &nbsp;!! m<sub>1</sub>!! m<sub>2</sub> !! m<sub>3</sub>!! m<sub>4</sub>!! m<sub>5</sub>!! m<sub>6</sub>!! m<sub>7</sub>!! m<sub>8</sub>!! m<sub>9</sub>!! m<sub>10</sub>!! m<sub>11</sub>!! m<sub>12</sub>!! m<sub>13</sub>
|-
| '''P<sub>1</sub>''' || 1 || 1 || 1 || 1 || &nbsp; || &nbsp; || &nbsp; || &nbsp; || &nbsp; || &nbsp; || &nbsp; || &nbsp; || &nbsp;
|-
| '''P<sub>2</sub>''' || 1 || &nbsp; || &nbsp; || &nbsp; || 1 || 1 || 1 || &nbsp; || &nbsp; || &nbsp; || &nbsp; || &nbsp; || &nbsp;
|-
| '''P<sub>3</sub>''' || 1 || &nbsp; ||&nbsp;|| &nbsp; || &nbsp; || &nbsp; || &nbsp; || 1|| 1 || 1 || &nbsp; || &nbsp; || &nbsp;
|-
| '''P<sub>4</sub>''' || 1 || &nbsp; || &nbsp; || &nbsp; || &nbsp; ||&nbsp;|| &nbsp;||&nbsp;||&nbsp; || &nbsp; || 1 || 1 || 1
|-
| '''P<sub>5</sub>''' || &nbsp; || 1 || &nbsp; || &nbsp; || 1 ||&nbsp;|| &nbsp;||1|| &nbsp; || &nbsp; || 1 || &nbsp; || &nbsp;
|-
| '''P<sub>6</sub>''' || &nbsp; || 1 || &nbsp; || &nbsp; || &nbsp; ||1|| &nbsp;||&nbsp;|| 1 || &nbsp; || &nbsp; || 1 || &nbsp;
|-
| '''P<sub>7</sub>''' ||  || 1 ||  ||  ||  || || 1|| ||  || 1 ||  ||  || 1
|-
| '''P<sub>8</sub>''' ||  ||  || 1 ||  || 1 || ||  || || 1 ||  ||  ||  || 1
|-
| '''P<sub>9</sub>''' ||  ||  || 1 ||  ||  ||1||  || ||  || 1 || 1 ||  || 
|-
| '''P<sub>10</sub>''' ||  ||  || 1 ||  ||  || || 1||1||  ||  ||  || 1 || 
|-
| '''P<sub>11</sub>''' ||  ||  ||  || 1 || 1 || ||  || ||  || 1 ||  || 1 || 
|-
| '''P<sub>12</sub>''' ||  ||  ||  || 1 ||  ||1||  ||1||  ||  ||  ||  || 1
|-
| '''P<sub>13</sub>''' ||  ||  ||  || 1 ||  || || 1|| || 1 ||  || 1 ||  || 
|}
 
To verify the conditions that make this a projective plane, observe that every two rows have exactly one common column in which 1's appear (every pair of distinct points are on exactly one common line) and that every two columns have exactly one common row in which 1's appear (every pair of distinct lines meet at exactly one point). Among many possibilities, the points P<sub>1</sub>,P<sub>4</sub>,P<sub>5</sub>,and P<sub>8</sub>, for example, will satisfy the third condition. This example is known as the '''''projective plane of order three'''''.
 
==Vector space construction==
 
The line at infinity of the extended real plane appears to have a different nature than the other lines of that projective plane. This, however, is not true. Another construction of the same projective plane shows that no line can be distinguished (on geometrical grounds) from any other. In this construction,  the "points" of the real projective plane are the lines through the origin in 3-dimensional Euclidean space, and a "line" in the projective plane arises from a plane through the origin in the 3-space. This idea can be generalized and made more precise as follows.<ref name="Baez2002">Baez (2002).</ref>
 
Let ''K'' be any [[division ring]] (skewfield). Let ''K''<sup>3</sup> denote the set of all triples ''x'' = (''x''<sub>0</sub>, ''x''<sub>1</sub>, ''x''<sub>2</sub>) of elements of ''K'' (a [[Cartesian product]] viewed as a [[Vector space]]). For any nonzero ''x'' in ''K''<sup>3</sup>, the ''line'' in ''K''<sup>3</sup> through the origin and ''x'' is the subset
:<math>\{ k x : k \in K \}</math>
of ''K''<sup>3</sup>. Similarly, let ''x'' and ''y'' be linearly independent elements of ''K''<sup>3</sup>, meaning that if ''kx'' + ''ly'' = 0 then ''k'' = ''l'' = 0. The ''plane'' through the origin, ''x'', and ''y'' in ''K''<sup>3</sup> is the subset
:<math>\{k x + l y : k, l \in K\}</math>
of ''K''<sup>3</sup>. This plane contains various lines through the origin which are obtained by fixing either ''k'' or ''l''.
 
The '''projective plane''' over ''K'', denoted PG(2,''K'') or ''K'''''P'''<sup>2</sup>, has a point set consisting of all the lines in ''K''<sup>3</sup> through the origin (each is a vector subspace of dimension 1). A subset ''L'' of PG(2,''K'') is a ''line'' in PG(2,''K'') if there exists a plane in ''K''<sup>3</sup> whose set of lines is exactly ''L'' (a vector subspace of dimension 2).
 
Verifying that this construction produces a projective plane is usually left as a linear algebra exercise.
 
An alternate (algebraic) view of this construction is as follows. The points of this projective plane are the equivalence classes of the set ''K''<sup>3</sup> ∖ {(0, 0, 0)} modulo the [[equivalence relation]]
:''x'' ~ ''kx'',  for all ''k'' in ''K''<sup>×</sup>.
Lines in the projective plane are defined exactly as above.
 
The coordinates (''x''<sub>0</sub>, ''x''<sub>1</sub>, ''x''<sub>2</sub>) of a point in PG(2,''K'') are called '''homogeneous coordinates'''. Each triple (''x''<sub>0</sub>, ''x''<sub>1</sub>, ''x''<sub>2</sub>) represents a well-defined point in PG(2,''K''), except for the triple (0, 0, 0), which represents no point. Each point in PG(2,''K''), however, is represented by many triples.
 
If ''K'' is a [[topological space]], then ''K'''''P'''<sup>2</sup>,  inherits a topology via the [[product topology|product]], [[subspace topology|subspace]], and [[quotient topology|quotient]] topologies.
 
===Classical examples===
 
The [[real projective plane]] '''RP'''<sup>2</sup>,  arises when ''K'' is taken to be the [[real number]]s, '''R'''. As a closed, non-orientable real 2-[[manifold]], it serves as a fundamental example in topology.<ref name="Bredon1993">The real projective plane appears 37 times in the index of Bredon (1993), for example.</ref>
 
In this construction consider the unit sphere centered at the origin in '''R'''<sup>3</sup>. Each of the '''R'''<sup>3</sup> lines in this construction intersects the sphere at two antipodal points. Since the '''R'''<sup>3</sup> line represents a point of '''RP'''<sup>2</sup>, we will obtain the same model of '''RP'''<sup>2</sup> by identifying the antipodal points of the sphere. The lines of '''RP'''<sup>2</sup> will be the great circles of the sphere after this identification of antipodal points. This description gives the standard model of [[Elliptic geometry]].
 
The [[complex projective plane]] '''CP'''<sup>2</sup>,  arises when ''K'' is taken to be the [[complex number]]s, '''C'''. It is a closed complex 2-manifold, and hence a closed, orientable real 4-manifold. It and projective planes over other [[Field (algebra)|fields]] serve as fundamental examples in [[algebraic geometry]].<ref name="Shafarevich1994">The projective planes over fields are used throughout Shafarevich (1994), for example.</ref>
 
The [[quaternionic projective space|quaternionic projective plane]] is also of independent interest.
 
===Finite field planes===
 
By [[Wedderburn's little theorem|Wedderburn's Theorem]], a finite division ring must be commutative and so a field. Thus, the finite examples of this construction are known as "field planes". Taking ''K'' to be the [[finite field]] of ''q'' = ''p''<sup>''n''</sup> elements with prime ''p'' produces a projective plane of ''q''<sup>2</sup> + ''q'' + 1 points. The field planes are usually denoted by PG(2,''q'') where PG stands for projective geometry, the "2" is the dimension and ''q'' is called the '''order''' of the plane (it is one less than the number of points on any line). The Fano plane, discussed below, is denoted by PG(2,2). The third example [[#Some Examples##A Finite Example|above]] is the projective plane PG(2,3).
 
[[File:fano plane.svg|thumb|right|The Fano plane. Points are shown as dots; lines are shown as lines or circles.]]
 
The [[Fano plane]] is the projective plane arising from the field of two elements. It is the smallest projective plane, with only seven points and seven lines. In the figure at right, the seven points are shown as small black balls, and the seven lines are shown as six line segments and a circle. However, one could equivalently consider the balls to be the "lines" and the line segments and circle to be the "points" – this is an example of [[duality (projective geometry)|duality]] in the projective plane: if the lines and points are interchanged, the result is still a projective plane (see [[#Duality|below]]). A permutation of the seven points that carries [[incidence (geometry)|collinear]] points (points on the same line) to collinear points is called a ''[[collineation]]'' or ''[[symmetry]]'' of the plane. The collineations of a geometry form a [[Group (mathematics)|group]] under composition, and for the Fano plane this group (PΓL(3,2) = PGL(3,2)) has 168 elements.
 
===Desargues' theorem and Desarguesian planes===
 
The [[Desargues' theorem|theorem of Desargues]] is universally valid in a projective plane if and only if the plane can be constructed from a three-dimensional vector space over a skewfield as [[#Vector space construction|above]].<ref>[[David Hilbert]] proved the more difficult "only if" part of this result.</ref> These planes are called '''Desarguesian planes''', named after [[Gérard Desargues]]. The real (or complex) projective plane and the projective plane of order 3 given [[Projective plane#Some examples|above]] are examples of Desarguesian projective planes. The projective planes that can not be constructed in this manner are called [[non-Desarguesian plane]]s, and the [[Moulton plane]] given [[Projective plane#Some examples|above]] is an example of one. The PG(2,''K'') notation is reserved for the Desarguesian planes.
 
==Subplanes==
 
A '''subplane''' of a projective plane is a subset of the points of the plane which themselves form a projective plane with the same incidence relations.
 
{{harv|Bruck|1955}} proves the following theorem. Let Π be a finite projective plane of order ''N'' with a proper subplane Π<sub>0</sub> of order ''M''. Then either ''N'' = ''M''<sup>2</sup> or ''N'' ≥ ''M''<sup>2</sup> + ''M''.
 
When ''N'' is a square, subplanes of order <math>\sqrt{N}</math> are called ''Baer subplanes''. Every point of the plane lies on a line of a Baer subplane and every line of the plane contains a point of the Baer subplane.
 
In the finite desarguesian planes PG(2,''p<sup>n</sup>''), the subplanes have orders which are the orders of the subfields of the finite field GF(''p<sup>n</sup>''), that is, ''p<sup>i</sup>'' where ''i'' is a divisor of ''n''. In non-desarguesian planes however, Bruck's theorem gives the only information about subplane orders. The case of equality in the inequality of this theorem is not known to occur. Whether or not there exists a subplane of order ''M'' in a plane of order ''N'' with ''M''<sup>2</sup> + ''M'' = ''N'' is an open question. If such subplanes existed there would be projective planes of composite (non-prime power) order.
 
===Fano subplanes===
 
A '''Fano subplane''' is a subplane isomorphic to PG(2,2), the unique projective plane of order 2.
 
If you consider a ''quadrangle'' (a set of 4 points no three collinear) in this plane, the points determine six of the lines of the plane. The remaining three points (called the ''diagonal points'' of the quadrangle) are the points where the lines that do not intersect at a point of the quadrangle meet. The seventh line consists of all the diagonal points (usually drawn as a circle or semicircle).
 
The name ''Fano'' for this subplane is really a misnomer. [[Gino Fano]] (1871–1952), in developing a new set of axioms for Euclidean geometry, took as an axiom that the diagonal points of any quadrangle are never collinear. This is called ''Fano's Axiom''. A Fano subplane however violates Fano's Axiom. They really should be called ''Anti-Fano subplanes'', but this name change has not had many supporters.
 
In finite desarguesian planes, PG(2,''q''), Fano subplanes exist if and only if ''q'' is even (that is, a power of 2). The situation in non-desarguesian planes is unsettled. They could exist in any non-desarguesian plane of order greater than 6, and indeed, they have been found in all non-desarguesian planes in which they have been looked for (in both odd and even orders).
 
An open question is: Does every non-desarguesian plane contain a Fano subplane?
 
A theorem concerning Fano subplanes  due to {{harv|Gleason|1956}} is:
 
:If every quadrangle in a finite projective plane has collinear diagonal points, then the plane is desarguesian (of even order).
 
==Affine planes==
 
Projectivization of the Euclidean plane produced the real projective plane. The inverse operation &mdash; starting with a projective plane, remove one line and all the points incident with that line &mdash; produces an '''affine plane'''.
 
===Definition===
More formally an '''[[Affine plane (incidence geometry)|affine plane]]''' consists of a set of '''lines''' and a set of '''points''', and a relation between points and lines called '''incidence''', having the following properties:
<div id="axioms-of-affine-planes">
#Given any two distinct points, there is exactly one line incident with both of them.
#Given any line l and any point P not incident with l, there is exactly one line incident with P that does not meet l.
#There are four points such that no line is incident with more than two of them.
</div>
The second condition means that there are  [[Parallel (geometry)|parallel lines]] and is known as [[John Playfair|Playfair's]] axiom. The expression "does not meet" in this condition is shorthand for "there does not exist a point incident with both lines."
 
The Euclidean plane and the Moulton plane are examples of infinite affine planes. A finite projective plane will produce a finite affine plane when one of its lines and the points on it are removed. The '''order''' of a finite affine plane is the number of points on any of its lines (this will be the same number as the order of the projective plane from which it comes). The affine planes which arise from the projective planes PG(2,''q'') are denoted by AG(2,''q'').
 
There is a projective plane of order ''N'' if and only if there is an [[affine plane (incidence geometry)|affine plane]] of order ''N''.  When there is only one affine plane of order ''N'' there is only one projective plane of order ''N'', but the converse is not true. The affine planes formed by the removal of different lines of the projective plane will be isomorphic if and only if the removed lines are in the same orbit of the collineation group of the projective plane. These statements hold for infinite projective planes as well.
 
===Construction of projective planes from affine planes===
 
The affine plane ''K''<sup>2</sup> over ''K'' embeds into ''K'''''P'''<sup>2</sup> via the map which sends affine (non-homogeneous) coordinates to homogeneous coordinates,
:(''x''<sub>1</sub>, ''x''<sub>2</sub>) → (1, ''x''<sub>1</sub>, ''x''<sub>2</sub>).
 
The complement of the image is the set of points of the form (0, ''x''<sub>1</sub>, ''x''<sub>2</sub>). From the point of view of the embedding just given, these points are the [[point at infinity|points at infinity]]. They constitute a line in ''K'''''P'''<sup>2</sup> &mdash; namely, the line arising from the plane
:{k (0, 0, 1) + l (0, 1, 0) : k, l ε K}
 
in ''K''<sup>3</sup> &mdash; called the [[line at infinity]]. The points at infinity are the "extra" points where parallel lines intersect in the construction of the extended real plane; the point (0, ''x''<sub>1</sub>, ''x''<sub>2</sub>) is where all lines of slope ''x''<sub>2</sub> / ''x''<sub>1</sub> intersect. Consider for example the two lines
: u = {(x, 0) : x ε ''K''}
: y = {(x, 1) : x ε ''K''}
 
in the affine plane ''K''<sup>2</sup>. These lines have slope 0 and do not intersect. They can be regarded as subsets of ''K'''''P'''<sup>2</sup> via the embedding above, but these subsets are not lines in ''K'''''P'''<sup>2</sup>. Add the point (0, 1, 0) to each subset; that is, let
: ū = {(1, x, 0) : x ε ''K''} U {(0, 1, 0)}
: ȳ = {(1, x, 1) : x ε ''K''} U {(0, 1, 0)}
 
These are lines in ''K'''''P'''<sup>2</sup>; ū arises from the plane
:{k (1, 0, 0) + l (0, 1, 0) : k, l ε ''K''}
 
in ''K''<sup>3</sup>, while ȳ arises from the plane
:{k (1, 0, 1) + l (0, 1, 0) : k, l ε ''K''}.
The projective lines ū and ȳ intersect at (0, 1, 0). In fact, all lines in ''K''<sup>2</sup> of slope 0, when projectivized in this manner, intersect at (0, 1, 0) in ''K'''''P'''<sup>2</sup>.
 
The embedding of ''K''<sup>2</sup> into ''K'''''P'''<sup>2</sup> given above is not unique. Each embedding produces its own notion of points at infinity. For example, the embedding
:(''x''<sub>1</sub>, ''x''<sub>2</sub>) → (''x''<sub>2</sub>, 1, ''x''<sub>1</sub>),
has as its complement those points of the form (''x''<sub>0</sub>, 0, ''x''<sub>2</sub>), which are then regarded as points at infinity.
 
When an affine plane does not have the form of ''K''<sup>2</sup> with ''K'' a division ring, it can still be embedded in a projective plane, but the construction used above does not work. A commonly used method for carrying out the embedding in this case involves expanding the set of affine coordinates and working in a more general "algebra".
 
===Generalized coordinates===
{{main|Planar ternary ring}}
 
One can construct a coordinate "ring"&mdash;a so-called [[planar ternary ring]] (not a genuine ring)&mdash;corresponding to any projective plane.  A planar ternary ring need not be a field or division ring, and there are many projective planes that are not constructed from a division ring.  They are called [[non-Desarguesian projective plane]]s and are an active area of research.  The [[Cayley plane]] is a projective plane over the [[octonion]]s is one of these because the octonions do not form a division ring.<ref name="Baez2002"/>
 
Conversely, given a planar ternary ring (R,T), a projective plane can be constructed (see below). The relationship is not one to one. A projective plane may be associated with several non-isomorphic planar ternary rings. The ternary operator T can be used to produce two binary operators on the set R, by:
: a + b = T(a,1,b), and
: a • b = T(a,b,0).
The ternary operator is '''''linear''''' if T(x,m,k) = x•m + k. When the set of coordinates of a projective plane actually form a ring, a linear ternary operator may be defined in this way, using the ring operations on the right, to produce a planar ternary ring.
 
Algebraic properties of this planar ternary coordinate ring turn out to correspond to geometric incidence properties of the plane. For example, [[Desargues' theorem]] corresponds to the coordinate ring being obtained from a [[division ring]], while [[Pappus's hexagon theorem|Pappus's theorem]] corresponds to this ring being obtained from a [[commutative]] field. A projective plane satisfying Pappus's theorem universally is called a ''Pappian plane''. [[Alternative algebra|Alternative]], not necessarily [[associative]], division algebras like the octonions correspond to [[Moufang plane]]s.
 
The only proof known of the purely geometric statement that Desargues' theorem implies Pappus' theorem in a finite projective plane (finite Desarguesian planes are Pappian) is through the algebraic route, by coordinates in a division ring, using [[Wedderburn's little theorem|Wedderburn's theorem]] that finite division rings must be commutative.  (The converse is true in any projective plane and is provable geometrically, but finiteness is essential in this statement as there are infinite Desarguesian planes which are not Pappian.)
 
To describe a finite projective plane of order ''N''(≥ 2) using non-homogeneous coordinates and a planar ternary ring:
:Let one point be labelled (''∞'').
:Label ''N'' points, (''r'') where ''r'' = 0, ..., (''N''&nbsp;&minus;&nbsp;1).
:Label ''N''<sup>2</sup> points, (''r'', ''c'') where ''r'', ''c'' = 0, ..., (''N''&nbsp;&minus;&nbsp;1).
On these points, construct the following lines:
:One line <nowiki>[</nowiki>''∞''<nowiki>]</nowiki> = { (''∞''), (0), ..., (''N''&nbsp;&minus;&nbsp;1)}
:''N'' lines <nowiki>[</nowiki>''c''<nowiki>]</nowiki> = {(''∞''), (''c'',0), ..., (''c'', ''N''&nbsp;&minus;&nbsp;1)}, where ''c'' = 0, ..., (''N''&nbsp;&minus;&nbsp;1)
:''N''<sup>2</sup> lines <nowiki>[</nowiki>''r'', ''c''<nowiki>]</nowiki> = {(''r'') and the points (''x'', '''T'''(''x'',''r'',''c'') }, where ''x'', ''r'', ''c'' = 0, ..., (''N''&nbsp;&minus;&nbsp;1) and '''T''' is the ternary operator of the planar ternary ring.
 
For example, for ''N''=2 we can use the symbols {0,1} associated with the finite field of order 2. The ternary operation defined by T(x,m,k) = xm + k with the operations on the right being the multiplication and addition in the field yields the following:
:One line <nowiki>[</nowiki>''∞''<nowiki>]</nowiki> = { (''∞''), (0), (1)},
:2 lines <nowiki>[</nowiki>''c''<nowiki>]</nowiki> = {(''∞''), (''c'',0), (''c'',1) : ''c'' = 0, 1},
::<nowiki>[</nowiki>0<nowiki>]</nowiki> = {(''∞''), (0,0), (0,1) }
::<nowiki>[</nowiki>1<nowiki>]</nowiki> = {(''∞''), (1,0), (1,1) }
:4 lines <nowiki>[</nowiki>''r'', ''c''<nowiki>]</nowiki>: (''r'') and the points  (''i'',''ir'' + ''c''), where i = 0, 1 : ''r'', ''c'' = 0, 1.
::<nowiki>[</nowiki>0,0<nowiki>]</nowiki>: {(0), (0,0), (1,0) }
::<nowiki>[</nowiki>0,1<nowiki>]</nowiki>: {(0), (0,1), (1,1) }
::<nowiki>[</nowiki>1,0<nowiki>]</nowiki>: {(1), (0,0), (1,1) }
::<nowiki>[</nowiki>1,1<nowiki>]</nowiki>: {(1), (0,1), (1,0) }
 
==Degenerate planes==
 
[[File:Degenerate planes wec.svg|thumb | (Non-empty) Degenerate Projective Planes]]
 
Degenerate planes do not fulfill the [[#axioms-of-projective-planes|third condition]] in the definition of a projective plane. They are not structurally complex enough to be interesting in their own right, but from time to time they arise as special cases in general arguments. There are seven degenerate planes {{harv | Albert | Sandler | 1968}}. They are:
<ol>
<li> the empty set;
<li> a single point, no lines;
<li> a single line, no points;
<li> a single point, a collection of lines, the point is incident with all of the lines;
<li> a single line, a collection of points, the points are all incident with the line;
<li> a point P incident with a line m, an arbitrary (can be empty) collection of lines all incident with P and an arbitrary collection of points all incident with m;
<li> a point P not incident with a line m, an arbitrary (perhaps empty) collection of lines all incident with P and all the points of intersection of these lines with m.
</ol>
These seven cases are not independent, the fourth and fifth can be considered as special cases of the sixth, while the second and third are special cases of the fourth and fifth respectively. The seven cases  can therefore be organized into two families of degenerate planes as follows (this representation is for finite degenerate planes, but may be extended to infinite ones in a natural way):
 
1) For any number of points ''P''<sub>1</sub>, ..., ''P''<sub>''n''</sub>, and lines ''L''<sub>1</sub>, ..., ''L''<sub>''m''</sub>,
 
:''L''<sub>1</sub> = { ''P''<sub>1</sub>, ''P''<sub>2</sub>, ..., ''P''<sub>''n''</sub>}
:''L''<sub>2</sub> = { ''P''<sub>1</sub> }
:''L''<sub>3</sub> = { ''P''<sub>1</sub> }
:...
:''L''<sub>''m''</sub> = { ''P''<sub>1</sub> }
 
2) For any number of points ''P''<sub>1</sub>, ..., ''P''<sub>''n''</sub>, and lines ''L''<sub>1</sub>, ..., ''L''<sub>''n''</sub>,  (same number of points as lines)
 
:''L''<sub>1</sub> = { ''P''<sub>2</sub>, ''P''<sub>3</sub>, ..., ''P''<sub>''n''</sub> }
:''L''<sub>2</sub> = { ''P''<sub>1</sub>, ''P''<sub>2</sub> }
:''L''<sub>3</sub> = { ''P''<sub>1</sub>, ''P''<sub>3</sub> }
:...
:''L''<sub>''n''</sub> = { ''P''<sub>1</sub>, ''P''<sub>''n''</sub> }
 
==Collineations==
{{Main| Collineation}}
 
A [[Collineation]] of a projective plane is a [[Bijective|bijective map]] of the plane to itself which maps points to points and lines to lines that preserves incidence, meaning that if σ is a bijection and point P is on line m, then P<sup>σ</sup> is on m<sup>σ</sup>.<ref>Geometers tend to like writing mappings in an exponential notation, so P<sup>σ</sup> means σ(P) in a more conventional notation.</ref>
 
If σ is a collineation of a projective plane, a point P with P = P<sup>σ</sup> is called a '''''fixed point''''' of σ, and a line m with m = m<sup>σ</sup> is called a '''''fixed line''''' of σ. The points on a fixed line need not be fixed points, their images under σ are just constrained to lie on this line. The collection of fixed points and fixed lines of a collineation form a '''''closed configuration''''', which is a system of points and lines that satisfy the first two but not necessarily the third condition in the [[#Definition|definition]] of a projective plane. Thus, the fixed point and fixed line structure for any collineation either form a projective plane by themselves, or a [[#Degenerate planes|degenerate plane]]. Collineations whose fixed structure forms a plane are called '''''planar collineations'''''.
 
===Homography===
{{Main|Projective transformation}}
 
A '''[[homography]]''' (or ''projective transformation'') of PG(2,''K'') is a collineation of this type of projective plane which is a linear transformation of the underlying vector space.  Using homogeneous coordinates they can be represented by invertible 3 &times; 3 matrices over ''K'' which act on the points of PG(2,''K'') by ''y'' = ''M'' ''x''<sup>T</sup>, where ''x'' and ''y'' are points in ''K''<sup>3</sup> (vectors) and ''M'' is an invertible 3 &times; 3 matrix over ''K''.<ref>The points are viewed as row vectors, so to make the matrix multiplication work in this expression, the point ''x'' must be written as a column vector.</ref> Two matrices represent the same projective transformation if one is a constant multiple of the other. Thus the group of projective transformations is the quotient of the [[general linear group]] by the scalar matrices called the [[projective linear group]].
 
Another type of collineation of PG(2,''K'') is induced by any [[automorphism]] of ''K'', these are called '''automorphic collineations'''. If α is an automorphism of ''K'', then the collineation given by (x<sub>0</sub>,x<sub>1</sub>,x<sub>2</sub>) → (x<sub>0</sub><sup>α</sup>,x<sub>1</sub><sup>α</sup>,x<sub>2</sub><sup>α</sup>) is an automorphic collineation. The [[fundamental theorem of projective geometry]] says that all the collineations of PG(2,''K'') are compositions of homographies and automorphic collineations. Automorphic collineations are planar collineations.
 
==Plane duality==
{{Main|Duality (projective geometry)}}
 
{{details|Incidence structure#Dual structure}}
A projective plane is defined axiomatically as an [[incidence structure]], in terms of a set ''P'' of points, a set ''L'' of lines, and an [[incidence relation]] ''I'' that determines which points lie on which lines. As P and L are only sets one can interchange their roles and define a '''plane dual structure'''.
 
By interchanging the role of "points" and "lines" in
:C=(P,L,I)
we obtain the dual structure
:C* =(L,P,I*),
where ''I*'' is the [[inverse relation]] of ''I''.
 
In a projective plane a statement involving points, lines and incidence between them that is obtained from another such statement by interchanging the words "point" and "line" and making whatever grammatical adjustments that are necessary, is called the '''plane dual statement''' of the first. The plane dual statement of "Two points are on a unique line." is "Two lines meet at a unique point." Forming the plane dual of a statement is known as ''dualizing'' the statement.
 
If a statement is true in a projective plane C, then the plane dual of that statement must be true in the dual plane C*. This follows since dualizing each statement in the proof "in C" gives a statement of the proof "in C*."
 
In the projective plane C, it can be shown that there exist four lines, no three of which are concurrent. Dualizing this theorem and the first two axioms in the definition of a projective plane shows that the plane dual structure C* is also a projective plane, called the '''dual plane''' of C.
 
If C and C* are isomorphic, then C is called '''''self-dual'''''. The projective planes PG(2,''K'') for any division ring ''K'' are self-dual. However, there are [[non-Desarguesian plane]]s which are not self-dual, such as the Hall planes and some that are, such as the [[Hughes plane]]s.
 
The '''''Principle of Plane Duality''''' says that dualizing any theorem in a self-dual projective plane C produces another theorem valid in C.
 
==Correlations==
{{main|correlation (projective geometry)}}
A '''duality''' is a map from a projective plane ''C'' = (''P'', ''L'', I) to its dual plane ''C''* = (''L'', ''P'', I*) (see [[#Plane duality|above]]) which preserves incidence. That is, a duality σ will map points to lines and lines to points (''P''<sup>σ</sup> = ''L'' and ''L''<sup>σ</sup> = ''P'') in such a way that if a point ''Q'' is on a line ''m'' (denoted by ''Q'' I ''m'') then ''Q''<sup>σ</sup> I* ''m''<sup>σ</sup> ⇔ ''m''<sup>σ</sup> I ''Q''<sup>σ</sup>.  A duality which is an isomorphism is called a '''correlation'''.<ref>{{harv|Dembowski|1968}}  pg.151.</ref> If a correlation exists then the projective plane ''C'' is self-dual.
 
In the special case that the projective plane is of the [[Projective space|PG(2,''K'')]] type, with ''K'' a division ring, a duality is called a '''reciprocity'''.<ref>{{harv|Casse|2006}} pg.94.</ref> These planes are always self-dual. By the [[fundamental theorem of projective geometry]] a reciprocity is the composition of an [[automorphic function]] of ''K'' and a [[homography]]. If the automorphism involved is the identity, then the reciprocity is called a '''projective correlation'''.
 
A correlation of order two (an [[Involution (mathematics)|involution]]) is called a '''polarity'''. If a correlation φ is not a polarity then φ<sup>2</sup> is a nontrivial collineation.
 
==Finite projective planes==
 
It can be shown that a projective plane has the same number of lines as it has points (infinite or finite).  Thus, for every finite projective plane there is an [[integer]] ''N'' ≥ 2 such that the plane has
:''N''<sup>2</sup> + ''N'' + 1 points,
:''N''<sup>2</sup> + ''N'' + 1 lines,
:''N'' + 1 points on each line, and
:''N'' + 1 lines through each point.
The number ''N'' is called the '''order''' of the projective plane. (See also the article on [[finite geometry]].)
 
Using the vector space construction with finite fields there exists a projective plane of order ''N'' = ''p''<sup>''n''</sup>, for each prime power ''p''<sup>''n''</sup>.  In fact, for all known finite projective planes, the order ''N'' is a prime power.
 
The existence of finite projective planes of other orders is an open question.  The only general restriction known on the order is the [[Bruck-Ryser-Chowla theorem]] that if the order ''N'' is [[modular arithmetic|congruent]] to 1 or 2 mod 4, it must be the sum of two squares.  This rules out ''N'' = 6.  The next case ''N'' = 10 has been ruled out by massive computer calculations.  Nothing more is known; in particular, the question of whether there exists a finite projective plane of order ''N'' = 12 is still open.
 
Another longstanding open problem is whether there exist finite projective planes of ''prime'' order which are not finite field planes (equivalently, whether there exists a non-Desarguesian projective plane of prime order).
 
A projective plane of order ''N'' is a Steiner S(2, ''N''&nbsp;+&nbsp;1, ''N''<sup>2</sup>&nbsp;+&nbsp;''N''&nbsp;+&nbsp;1) system
(see [[Steiner system]]).  Conversely, one can prove that all Steiner systems of this form (λ = 2) are projective planes.
 
The number of mutually [[orthogonal Latin squares]] of order ''N'' is at most ''N'' &minus; 1.  ''N'' &minus; 1 exist if and only if there is a projective plane of order ''N''.
 
While the classification of all projective planes is far from complete, results are known for small orders:
*2 : all isomorphic with PG(2,2)
*3 : all isomorphic with PG(2,3)
*4 : all isomorphic with PG(2,4)
*5 : all isomorphic with PG(2,5)
*6 : impossible as the order of a projective plane, proved by [[Gaston Tarry|Tarry]] who showed that [[Euler]]'s [[thirty-six officers problem]] has no solution
*7 : all isomorphic with PG(2,7)
*8 : all isomorphic with PG(2,8)
*9 : PG(2,9), and three more different (non-isomorphic) [[non-Desarguesian plane]]s.  (All described in {{harv | Room | Kirkpatrick | 1971}}).
*10 : impossible as an order of a projective plane, proved by heavy computer calculation.<ref>{{harv|Lam|1991}}</ref>
*11 : at least PG(2,11), others are not known but possible.
*12 : it is conjectured to be impossible as an order of a projective plane.
 
==Projective planes in higher dimensional projective spaces==
 
Projective planes may be thought of as [[Projective geometry|projective geometries]] of "geometric" dimension two.<ref>There are competing notions of ''dimension'' in geometry and algebra (vector spaces). In geometry, lines are 1 dimensional, planes are 2 dimensional, solids are 3 dimensional, etc. In a vector space however, the dimension is the number of vectors in a basis. When geometries are constructed from vector spaces, these two notions of dimension can lead to confusion, so it is often the case that the geometric concept is called ''geometric'' or ''projective'' dimension and the other is ''algebraic'' or ''vector space'' dimension. The two concepts are numerically related by: algebraic dimension = geometric dimension + 1.</ref> Higher dimensional projective geometries can be defined in terms of incidence relations in a manner analogous to the definition of a projective plane. These turn out to be "tamer" than the projective planes since the extra degrees of freedom permit [[Desargues' theorem]] to be proved geometrically in the higher dimensional geometry. This means that the coordinate "ring" associated to the geometry must be a division ring (skewfield) ''K'',  and the projective geometry is isomorphic to the one constructed from the vector space  ''K''<sup>''d''+1</sup>, i.e. PG(''d'',''K''). As in the construction given earlier, the points of the ''d''-dimensional [[projective space]]  PG(''d'',''K'') are the lines through the origin in ''K''<sup>''d'' + 1</sup> and a line in  PG(''d'',''K'') corresponds to a plane through the origin in ''K''<sup>''d'' + 1</sup>.  In fact, each ''i-dimensional'' object in  PG(''d'',''K''), with ''i'' &lt; ''d'',  is an (i+1)-dimensional (algebraic) vector subspace of ''K''<sup>''d'' + 1</sup> ("goes through the origin"). The projective spaces in turn generalize to the [[Grassmannian|Grassmannian spaces]].
 
It can be shown that if Desargues' theorem holds in a projective space of dimension greater than two, then it must also hold in all planes that are contained in that space. Since there are projective planes in which Desargues' theorem fails ([[non-Desarguesian plane]]s), these planes can not be embedded in a higher dimensional projective space. Only the planes from the vector space construction PG(2,''K'') can appear in projective spaces of higher dimension. Some disciplines in mathematics restrict the meaning of projective plane to only this type of projective plane since otherwise general statements about projective spaces would always have to mention the exceptions when the geometric dimension is two.<ref>"One might say, with some justice, that projective geometry, in so far as present day research is concerned, has split into two quite separate fields. On the one hand, the researcher into the foundations of geometry tends to regard Desarguesian spaces as completely known. Since the only possible non-Desarguesian spaces are planes, his attention is restricted to the theory of projective planes, especially the non- Desarguesian planes. On the other hand stand all those researchers - and especially, the algebraic geometers - who are unwilling to be bound to two-dimensional space and uninterested in permitting non-Desarguesian planes to assume an exceptional role in their theorems. For the latter group of researchers, there are no projective spaces except the Desarguesian spaces." {{harv|Bruck|Bose|1964|loc=Introduction}}</ref>
 
==See also==
*[[Block design]]
*[[Combinatorial design]]
*[[Incidence structure]]
*[[Projective geometry]]
*[[Non-Desarguesian plane]]
 
==Notes==
{{reflist}}
 
==References==
*{{Citation | last1 = Albert | first1 = A. Adrian |author1-link=Abraham Adrian Albert| last2 = Sandler | first2 = Reuben | title = An Introduction to Finite Projective Planes | publisher = Holt, Rinehart and Winston | place = New York | year = 1968}}
*{{citation|first=John C.|last=Baez|authorlink=John C. Baez|title=The octonions|journal=Bull. Amer. Math. Soc.|volume= 39|year=2002|pages=145–205|url=http://math.ucr.edu/home/baez/octonions/|doi=10.1090/S0273-0979-01-00934-X}}
*{{citation | first=Glen E. | last=Bredon | authorlink=Glen Bredon | title=Topology and Geometry | publisher=Springer-Verlag | year=1993 | isbn=0-387-97926-3}}
* {{citation|last=Bruck|first=R. H.|authorlink=Richard Bruck|title=Difference Sets in a Finite Group|journal=Trans. Amer. Math. Soc.|year=1955|volume=78|pages=464–481}}
* {{citation|last=Bruck|first=R. H.|author1-link=Richard Bruck|last2=Bose|first2=R. C.|author2-link=Raj Chandra Bose|title=The Construction of Translation Planes from Projective Spaces|journal=J. Algebra|year=1964|volume=1|pages=85–102}}
* {{Citation | last = Casse | first = Rey | title = Projective Geometry: An Introduction | publisher = Oxford University Press | place = Oxford | year = 2006 | isbn =0-19-929886-6 }}
* {{Citation | last1=Dembowski | first1=Peter | title=Finite geometries | publisher=[[Springer-Verlag]] | location=Berlin, New York | series=[[Ergebnisse der Mathematik und ihrer Grenzgebiete]], Band 44 | mr=0233275  | year=1968 | isbn=3-540-61786-8}}
*{{citation
| last = Gleason | first = Andrew M. | authorlink = Andrew Gleason
| doi = 10.2307/2372469
| journal = [[American Journal of Mathematics]]
| mr = 0082684
| pages = 797–807
| title = Finite Fano planes
| volume = 78
| year = 1956}}
*{{Citation | last1=Hall | first1=Marshall |authorlink=Marshall Hall (mathematician)| title=Projective planes | jstor=1990331 | mr=0008892  | year=1943 | journal=[[Transactions of the American Mathematical Society]] | issn=0002-9947 | volume=54 | pages=229–277 | issue=2 | publisher=American Mathematical Society}}
*{{citation | first1=D.|last1= Hughes|first2= F.|last2=Piper | title=Projective Planes | publisher=Springer-Verlag | year=1973 | isbn=0-387-90044-6}}
*{{Citation | last = Kárteszi | first = F. | title = Introduction to Finite Geometries| publisher = North-Holland | place = Amsterdam | year = 1976 | isbn = 0-7204-2832-7}}
*{{citation| last = Lam | first = Clement W. H. | title=The Search for a Finite Projective Plane of order 10 | journal=American Mathematical Monthly | year = 1991| volume = 98 | issue= 4| pages=305–318| url=http://www.cecm.sfu.ca/organics/papers/lam/}}
*Lindner, Charles C. and Christopher A. Rodger (eds.) ''Design Theory'', CRC-Press; 1 edition (October 31, 1997). ISBN 0-8493-3986-3.
*{{Citation | last = Lüneburg | first = Heinz | title = Translation Planes | publisher = Springer Verlag | place = Berlin | year = 1980 | isbn = 0-387-09614-0}}
*{{Citation | last1=Moulton | first1=Forest Ray | authorlink = Forest Ray Moulton | title=A Simple Non-Desarguesian Plane Geometry | jstor=1986419 | year=1902 | journal=[[Transactions of the American Mathematical Society]] | issn=0002-9947 | volume=3 | issue=2 | pages=192–195}}
*{{Citation | last1 = Room | first1 = T. G.|author1-link=Thomas Gerald Room | last2 = Kirkpatrick | first2 = P. B. | title = Miniquaternion Geometry | publisher = Cambridge University Press | place = Cambridge | year = 1971 |isbn = 0-521-07926-8}}
*{{citation | first=I. R.|last=Shafarevich |authorlink=Igor Shafarevich| title=Basic Algebraic Geometry | publisher=Springer-Verlag | year=1994 | isbn=0-387-54812-2}}
*{{Citation | last = Stevenson | first = Frederick W. | title = Projective Planes | publisher = W.H. Freeman and Company | place = San Francisco |year = 1972 | isbn = 0-7167-0443-9}}
 
==External links==
*G. Eric Moorhouse, ''[http://www.uwyo.edu/moorhouse/pub/planes/ Projective Planes of Small Order]'', (2003)
*[http://www.ams.org/notices/200710/tx071001294p.pdf Ch. Weibel: Survey of Nondesarguesian planes ]
*{{mathworld|urlname=ProjectivePlane|title=Projective plane}}
 
{{DEFAULTSORT:Projective Plane}}
[[Category:Projective geometry]]
[[Category:Incidence geometry]]
[[Category:Euclidean plane geometry]]
[[Category:Algebraic geometry]]

Revision as of 15:44, 18 December 2013

Parallel lines intersect in the vanishing point at infinity.

In mathematics, a projective plane is a geometric structure that extends the concept of a plane. In the ordinary Euclidean plane, two lines typically intersect in a single point, but there are some pairs of lines (namely, parallel lines) that do not intersect. A projective plane can be thought of as an ordinary plane equipped with additional "points at infinity" where parallel lines intersect. Thus any two lines in a projective plane intersect in one and only one point.

Renaissance artists, in developing the techniques of drawing in perspective, laid the groundwork for this mathematical topic. The archetypical example is the real projective plane, also known as the Extended Euclidean Plane. This example, in slightly different guises, is important in algebraic geometry, topology and projective geometry where it may be denoted variously by PG(2,R), RP2, or P2(R) among other notations. There are many other projective planes, both infinite, such as the complex projective plane, and finite, such as the Fano plane.

A projective plane is a 2-dimensional projective space, but not all projective planes can be embedded in 3-dimensional projective spaces. The embedding property is a consequence of a result known as Desargues' theorem.

Definition

A projective plane consists of a set of lines, a set of points, and a relation between points and lines called incidence, having the following properties:[1]

  1. Given any two distinct points, there is exactly one line incident with both of them.
  2. Given any two distinct lines, there is exactly one point incident with both of them.
  3. There are four points such that no line is incident with more than two of them.

The second condition means that there are no parallel lines. The last condition excludes the so-called degenerate cases (see below). The term "incidence" is used to emphasize the symmetric nature of the relationship between points and lines. Thus the expression "point P is incident with line l " is used instead of either "P is on l " or "l passes through P ".

Some examples

The Extended Euclidean Plane

To turn the ordinary Euclidean plane into a projective plane proceed as follows:

1. To each class of parallel lines add a single new point. That point is considered incident with each line of the class. Different parallel classes get different points. These points are called points at infinity.
2. Add a new line which is considered incident with all the points at infinity (and only them). This line is called the line at infinity.

The extended structure is a projective plane and is called the Extended Euclidean Plane or the real projective plane. The process outlined above, used to obtain it, is called "projective completion" or projectivization. This plane can also be constructed by starting from R3 viewed as a vector space, see below.

Projective Moulton Plane

The points of the Moulton plane are the points of the Euclidean plane, with coordinates in the usual way. To create the Moulton plane from the Euclidean plane some of the lines are redefined. That is, some of their point sets will be changed, but other lines will remain unchanged. Redefine all the lines with negative slopes so that they look like "bent" lines, meaning that these lines keep their points with negative x-coordinates, but the rest of their points are replaced with the points of the line with the same y-intercept but twice the slope wherever their x-coordinate is positive.

See Moulton plane for a diagram and the specific formulas. This Moulton plane has parallel classes of lines, and it can be used for projections as in the previous example to obtain the Projective Moulton Plane. Desargues' Theorem is not a valid theorem in either the Moulton plane or the Projective Moulton plane.

A finite example

This example has just thirteen points and thirteen lines. We label the points P1,...,P13 and the lines m1,...,m13. The incidence relation (which points are on which lines) can be given by the following incidence matrix. The rows are labelled by the points and the columns are labelled by the lines. A 1 in row i and column j means that the point Pi is on the line mj, while a 0 (which we represent here by a blank cell for ease of reading) means that they are not incident. The matrix is in Paige-Wexler normal form.

  m1 m2 m3 m4 m5 m6 m7 m8 m9 m10 m11 m12 m13
P1 1 1 1 1                  
P2 1       1 1 1            
P3 1             1 1 1      
P4 1                   1 1 1
P5   1     1     1     1    
P6   1       1     1     1  
P7 1 1 1 1
P8 1 1 1 1
P9 1 1 1 1
P10 1 1 1 1
P11 1 1 1 1
P12 1 1 1 1
P13 1 1 1 1

To verify the conditions that make this a projective plane, observe that every two rows have exactly one common column in which 1's appear (every pair of distinct points are on exactly one common line) and that every two columns have exactly one common row in which 1's appear (every pair of distinct lines meet at exactly one point). Among many possibilities, the points P1,P4,P5,and P8, for example, will satisfy the third condition. This example is known as the projective plane of order three.

Vector space construction

The line at infinity of the extended real plane appears to have a different nature than the other lines of that projective plane. This, however, is not true. Another construction of the same projective plane shows that no line can be distinguished (on geometrical grounds) from any other. In this construction, the "points" of the real projective plane are the lines through the origin in 3-dimensional Euclidean space, and a "line" in the projective plane arises from a plane through the origin in the 3-space. This idea can be generalized and made more precise as follows.[2]

Let K be any division ring (skewfield). Let K3 denote the set of all triples x = (x0, x1, x2) of elements of K (a Cartesian product viewed as a Vector space). For any nonzero x in K3, the line in K3 through the origin and x is the subset

of K3. Similarly, let x and y be linearly independent elements of K3, meaning that if kx + ly = 0 then k = l = 0. The plane through the origin, x, and y in K3 is the subset

of K3. This plane contains various lines through the origin which are obtained by fixing either k or l.

The projective plane over K, denoted PG(2,K) or KP2, has a point set consisting of all the lines in K3 through the origin (each is a vector subspace of dimension 1). A subset L of PG(2,K) is a line in PG(2,K) if there exists a plane in K3 whose set of lines is exactly L (a vector subspace of dimension 2).

Verifying that this construction produces a projective plane is usually left as a linear algebra exercise.

An alternate (algebraic) view of this construction is as follows. The points of this projective plane are the equivalence classes of the set K3 ∖ {(0, 0, 0)} modulo the equivalence relation

x ~ kx, for all k in K×.

Lines in the projective plane are defined exactly as above.

The coordinates (x0, x1, x2) of a point in PG(2,K) are called homogeneous coordinates. Each triple (x0, x1, x2) represents a well-defined point in PG(2,K), except for the triple (0, 0, 0), which represents no point. Each point in PG(2,K), however, is represented by many triples.

If K is a topological space, then KP2, inherits a topology via the product, subspace, and quotient topologies.

Classical examples

The real projective plane RP2, arises when K is taken to be the real numbers, R. As a closed, non-orientable real 2-manifold, it serves as a fundamental example in topology.[3]

In this construction consider the unit sphere centered at the origin in R3. Each of the R3 lines in this construction intersects the sphere at two antipodal points. Since the R3 line represents a point of RP2, we will obtain the same model of RP2 by identifying the antipodal points of the sphere. The lines of RP2 will be the great circles of the sphere after this identification of antipodal points. This description gives the standard model of Elliptic geometry.

The complex projective plane CP2, arises when K is taken to be the complex numbers, C. It is a closed complex 2-manifold, and hence a closed, orientable real 4-manifold. It and projective planes over other fields serve as fundamental examples in algebraic geometry.[4]

The quaternionic projective plane is also of independent interest.

Finite field planes

By Wedderburn's Theorem, a finite division ring must be commutative and so a field. Thus, the finite examples of this construction are known as "field planes". Taking K to be the finite field of q = pn elements with prime p produces a projective plane of q2 + q + 1 points. The field planes are usually denoted by PG(2,q) where PG stands for projective geometry, the "2" is the dimension and q is called the order of the plane (it is one less than the number of points on any line). The Fano plane, discussed below, is denoted by PG(2,2). The third example above is the projective plane PG(2,3).

The Fano plane. Points are shown as dots; lines are shown as lines or circles.

The Fano plane is the projective plane arising from the field of two elements. It is the smallest projective plane, with only seven points and seven lines. In the figure at right, the seven points are shown as small black balls, and the seven lines are shown as six line segments and a circle. However, one could equivalently consider the balls to be the "lines" and the line segments and circle to be the "points" – this is an example of duality in the projective plane: if the lines and points are interchanged, the result is still a projective plane (see below). A permutation of the seven points that carries collinear points (points on the same line) to collinear points is called a collineation or symmetry of the plane. The collineations of a geometry form a group under composition, and for the Fano plane this group (PΓL(3,2) = PGL(3,2)) has 168 elements.

Desargues' theorem and Desarguesian planes

The theorem of Desargues is universally valid in a projective plane if and only if the plane can be constructed from a three-dimensional vector space over a skewfield as above.[5] These planes are called Desarguesian planes, named after Gérard Desargues. The real (or complex) projective plane and the projective plane of order 3 given above are examples of Desarguesian projective planes. The projective planes that can not be constructed in this manner are called non-Desarguesian planes, and the Moulton plane given above is an example of one. The PG(2,K) notation is reserved for the Desarguesian planes.

Subplanes

A subplane of a projective plane is a subset of the points of the plane which themselves form a projective plane with the same incidence relations.

Template:Harv proves the following theorem. Let Π be a finite projective plane of order N with a proper subplane Π0 of order M. Then either N = M2 or NM2 + M.

When N is a square, subplanes of order are called Baer subplanes. Every point of the plane lies on a line of a Baer subplane and every line of the plane contains a point of the Baer subplane.

In the finite desarguesian planes PG(2,pn), the subplanes have orders which are the orders of the subfields of the finite field GF(pn), that is, pi where i is a divisor of n. In non-desarguesian planes however, Bruck's theorem gives the only information about subplane orders. The case of equality in the inequality of this theorem is not known to occur. Whether or not there exists a subplane of order M in a plane of order N with M2 + M = N is an open question. If such subplanes existed there would be projective planes of composite (non-prime power) order.

Fano subplanes

A Fano subplane is a subplane isomorphic to PG(2,2), the unique projective plane of order 2.

If you consider a quadrangle (a set of 4 points no three collinear) in this plane, the points determine six of the lines of the plane. The remaining three points (called the diagonal points of the quadrangle) are the points where the lines that do not intersect at a point of the quadrangle meet. The seventh line consists of all the diagonal points (usually drawn as a circle or semicircle).

The name Fano for this subplane is really a misnomer. Gino Fano (1871–1952), in developing a new set of axioms for Euclidean geometry, took as an axiom that the diagonal points of any quadrangle are never collinear. This is called Fano's Axiom. A Fano subplane however violates Fano's Axiom. They really should be called Anti-Fano subplanes, but this name change has not had many supporters.

In finite desarguesian planes, PG(2,q), Fano subplanes exist if and only if q is even (that is, a power of 2). The situation in non-desarguesian planes is unsettled. They could exist in any non-desarguesian plane of order greater than 6, and indeed, they have been found in all non-desarguesian planes in which they have been looked for (in both odd and even orders).

An open question is: Does every non-desarguesian plane contain a Fano subplane?

A theorem concerning Fano subplanes due to Template:Harv is:

If every quadrangle in a finite projective plane has collinear diagonal points, then the plane is desarguesian (of even order).

Affine planes

Projectivization of the Euclidean plane produced the real projective plane. The inverse operation — starting with a projective plane, remove one line and all the points incident with that line — produces an affine plane.

Definition

More formally an affine plane consists of a set of lines and a set of points, and a relation between points and lines called incidence, having the following properties:

  1. Given any two distinct points, there is exactly one line incident with both of them.
  2. Given any line l and any point P not incident with l, there is exactly one line incident with P that does not meet l.
  3. There are four points such that no line is incident with more than two of them.

The second condition means that there are parallel lines and is known as Playfair's axiom. The expression "does not meet" in this condition is shorthand for "there does not exist a point incident with both lines."

The Euclidean plane and the Moulton plane are examples of infinite affine planes. A finite projective plane will produce a finite affine plane when one of its lines and the points on it are removed. The order of a finite affine plane is the number of points on any of its lines (this will be the same number as the order of the projective plane from which it comes). The affine planes which arise from the projective planes PG(2,q) are denoted by AG(2,q).

There is a projective plane of order N if and only if there is an affine plane of order N. When there is only one affine plane of order N there is only one projective plane of order N, but the converse is not true. The affine planes formed by the removal of different lines of the projective plane will be isomorphic if and only if the removed lines are in the same orbit of the collineation group of the projective plane. These statements hold for infinite projective planes as well.

Construction of projective planes from affine planes

The affine plane K2 over K embeds into KP2 via the map which sends affine (non-homogeneous) coordinates to homogeneous coordinates,

(x1, x2) → (1, x1, x2).

The complement of the image is the set of points of the form (0, x1, x2). From the point of view of the embedding just given, these points are the points at infinity. They constitute a line in KP2 — namely, the line arising from the plane

{k (0, 0, 1) + l (0, 1, 0) : k, l ε K}

in K3 — called the line at infinity. The points at infinity are the "extra" points where parallel lines intersect in the construction of the extended real plane; the point (0, x1, x2) is where all lines of slope x2 / x1 intersect. Consider for example the two lines

u = {(x, 0) : x ε K}
y = {(x, 1) : x ε K}

in the affine plane K2. These lines have slope 0 and do not intersect. They can be regarded as subsets of KP2 via the embedding above, but these subsets are not lines in KP2. Add the point (0, 1, 0) to each subset; that is, let

ū = {(1, x, 0) : x ε K} U {(0, 1, 0)}
ȳ = {(1, x, 1) : x ε K} U {(0, 1, 0)}

These are lines in KP2; ū arises from the plane

{k (1, 0, 0) + l (0, 1, 0) : k, l ε K}

in K3, while ȳ arises from the plane

{k (1, 0, 1) + l (0, 1, 0) : k, l ε K}.

The projective lines ū and ȳ intersect at (0, 1, 0). In fact, all lines in K2 of slope 0, when projectivized in this manner, intersect at (0, 1, 0) in KP2.

The embedding of K2 into KP2 given above is not unique. Each embedding produces its own notion of points at infinity. For example, the embedding

(x1, x2) → (x2, 1, x1),

has as its complement those points of the form (x0, 0, x2), which are then regarded as points at infinity.

When an affine plane does not have the form of K2 with K a division ring, it can still be embedded in a projective plane, but the construction used above does not work. A commonly used method for carrying out the embedding in this case involves expanding the set of affine coordinates and working in a more general "algebra".

Generalized coordinates

Mining Engineer (Excluding Oil ) Truman from Alma, loves to spend time knotting, largest property developers in singapore developers in singapore and stamp collecting. Recently had a family visit to Urnes Stave Church.

One can construct a coordinate "ring"—a so-called planar ternary ring (not a genuine ring)—corresponding to any projective plane. A planar ternary ring need not be a field or division ring, and there are many projective planes that are not constructed from a division ring. They are called non-Desarguesian projective planes and are an active area of research. The Cayley plane is a projective plane over the octonions is one of these because the octonions do not form a division ring.[2]

Conversely, given a planar ternary ring (R,T), a projective plane can be constructed (see below). The relationship is not one to one. A projective plane may be associated with several non-isomorphic planar ternary rings. The ternary operator T can be used to produce two binary operators on the set R, by:

a + b = T(a,1,b), and
a • b = T(a,b,0).

The ternary operator is linear if T(x,m,k) = x•m + k. When the set of coordinates of a projective plane actually form a ring, a linear ternary operator may be defined in this way, using the ring operations on the right, to produce a planar ternary ring.

Algebraic properties of this planar ternary coordinate ring turn out to correspond to geometric incidence properties of the plane. For example, Desargues' theorem corresponds to the coordinate ring being obtained from a division ring, while Pappus's theorem corresponds to this ring being obtained from a commutative field. A projective plane satisfying Pappus's theorem universally is called a Pappian plane. Alternative, not necessarily associative, division algebras like the octonions correspond to Moufang planes.

The only proof known of the purely geometric statement that Desargues' theorem implies Pappus' theorem in a finite projective plane (finite Desarguesian planes are Pappian) is through the algebraic route, by coordinates in a division ring, using Wedderburn's theorem that finite division rings must be commutative. (The converse is true in any projective plane and is provable geometrically, but finiteness is essential in this statement as there are infinite Desarguesian planes which are not Pappian.)

To describe a finite projective plane of order N(≥ 2) using non-homogeneous coordinates and a planar ternary ring:

Let one point be labelled ().
Label N points, (r) where r = 0, ..., (N − 1).
Label N2 points, (r, c) where r, c = 0, ..., (N − 1).

On these points, construct the following lines:

One line [] = { (), (0), ..., (N − 1)}
N lines [c] = {(), (c,0), ..., (c, N − 1)}, where c = 0, ..., (N − 1)
N2 lines [r, c] = {(r) and the points (x, T(x,r,c) }, where x, r, c = 0, ..., (N − 1) and T is the ternary operator of the planar ternary ring.

For example, for N=2 we can use the symbols {0,1} associated with the finite field of order 2. The ternary operation defined by T(x,m,k) = xm + k with the operations on the right being the multiplication and addition in the field yields the following:

One line [] = { (), (0), (1)},
2 lines [c] = {(), (c,0), (c,1) : c = 0, 1},
[0] = {(), (0,0), (0,1) }
[1] = {(), (1,0), (1,1) }
4 lines [r, c]: (r) and the points (i,ir + c), where i = 0, 1 : r, c = 0, 1.
[0,0]: {(0), (0,0), (1,0) }
[0,1]: {(0), (0,1), (1,1) }
[1,0]: {(1), (0,0), (1,1) }
[1,1]: {(1), (0,1), (1,0) }

Degenerate planes

File:Degenerate planes wec.svg
(Non-empty) Degenerate Projective Planes

Degenerate planes do not fulfill the third condition in the definition of a projective plane. They are not structurally complex enough to be interesting in their own right, but from time to time they arise as special cases in general arguments. There are seven degenerate planes Template:Harv. They are:

  1. the empty set;
  2. a single point, no lines;
  3. a single line, no points;
  4. a single point, a collection of lines, the point is incident with all of the lines;
  5. a single line, a collection of points, the points are all incident with the line;
  6. a point P incident with a line m, an arbitrary (can be empty) collection of lines all incident with P and an arbitrary collection of points all incident with m;
  7. a point P not incident with a line m, an arbitrary (perhaps empty) collection of lines all incident with P and all the points of intersection of these lines with m.

These seven cases are not independent, the fourth and fifth can be considered as special cases of the sixth, while the second and third are special cases of the fourth and fifth respectively. The seven cases can therefore be organized into two families of degenerate planes as follows (this representation is for finite degenerate planes, but may be extended to infinite ones in a natural way):

1) For any number of points P1, ..., Pn, and lines L1, ..., Lm,

L1 = { P1, P2, ..., Pn}
L2 = { P1 }
L3 = { P1 }
...
Lm = { P1 }

2) For any number of points P1, ..., Pn, and lines L1, ..., Ln, (same number of points as lines)

L1 = { P2, P3, ..., Pn }
L2 = { P1, P2 }
L3 = { P1, P3 }
...
Ln = { P1, Pn }

Collineations

Mining Engineer (Excluding Oil ) Truman from Alma, loves to spend time knotting, largest property developers in singapore developers in singapore and stamp collecting. Recently had a family visit to Urnes Stave Church.

A Collineation of a projective plane is a bijective map of the plane to itself which maps points to points and lines to lines that preserves incidence, meaning that if σ is a bijection and point P is on line m, then Pσ is on mσ.[6]

If σ is a collineation of a projective plane, a point P with P = Pσ is called a fixed point of σ, and a line m with m = mσ is called a fixed line of σ. The points on a fixed line need not be fixed points, their images under σ are just constrained to lie on this line. The collection of fixed points and fixed lines of a collineation form a closed configuration, which is a system of points and lines that satisfy the first two but not necessarily the third condition in the definition of a projective plane. Thus, the fixed point and fixed line structure for any collineation either form a projective plane by themselves, or a degenerate plane. Collineations whose fixed structure forms a plane are called planar collineations.

Homography

Mining Engineer (Excluding Oil ) Truman from Alma, loves to spend time knotting, largest property developers in singapore developers in singapore and stamp collecting. Recently had a family visit to Urnes Stave Church.

A homography (or projective transformation) of PG(2,K) is a collineation of this type of projective plane which is a linear transformation of the underlying vector space. Using homogeneous coordinates they can be represented by invertible 3 × 3 matrices over K which act on the points of PG(2,K) by y = M xT, where x and y are points in K3 (vectors) and M is an invertible 3 × 3 matrix over K.[7] Two matrices represent the same projective transformation if one is a constant multiple of the other. Thus the group of projective transformations is the quotient of the general linear group by the scalar matrices called the projective linear group.

Another type of collineation of PG(2,K) is induced by any automorphism of K, these are called automorphic collineations. If α is an automorphism of K, then the collineation given by (x0,x1,x2) → (x0α,x1α,x2α) is an automorphic collineation. The fundamental theorem of projective geometry says that all the collineations of PG(2,K) are compositions of homographies and automorphic collineations. Automorphic collineations are planar collineations.

Plane duality

Mining Engineer (Excluding Oil ) Truman from Alma, loves to spend time knotting, largest property developers in singapore developers in singapore and stamp collecting. Recently had a family visit to Urnes Stave Church.

DTZ gives a comprehensive integrated property and services administration resolution for buyers, corporate house for sale In singapore owners, management firms and occupiers of property whatever their needs with the only goal of optimising and enhancing the investment worth of their property. We at the moment make use of a staff of more than 70 skilled staffs who are well-trained and dedicated to collectively achieving our purchasers' objectives.

Actual estate agency specialising in non-public condos and landed properties island vast. 10 Winstedt Highway, District 10, #01-thirteen, Singapore 227977. Property providers for enterprise relocation. Situated at 371 Beach Street, #19-10 KeyPoint, Singapore 199597. Property agents for homes, town houses, landed property, residences and condominium for sales and rentals of properties. Administration letting services for property homeowners. is there a single authority in singapore who regulates real property agents that i can file a complaint with for unethical behaviour? or is CASE is simply route? The 188 pages of Secrets and techniques of Singapore Property Gurus are full of professional knowledge and life altering wisdom. Asian industrial property market outlook Property Listing Supervisor Property Advertising Services

Should sellers go along with an agent who claims to specialize in your space? His experience might turn out to be useful, but he is probably additionally advertising a number of models within the neighbourhood – and so they're all your rivals. Within the worst-case state of affairs, your house may be used as a "showflat" as house owner YS Liang found. "Weekend after weekend, our agent would convey a stream of individuals to speed-go to our apartment, leaving within minutes. She did not even try to promote our condominium. It felt like we were just one of the many tour stops for her clients," he complains.

Step one in direction of conducting enterprise as an actual property company in Singapore is to include an organization, or if you happen to're going the partnership or sole-proprietorship route, register your Limited Legal responsibility Partnership or sole-proprietorship with the ACRA (Accounting and Company Regulatory Authority of Singapore) Whether or not you might be considering to promote, let, hire or buy a new industrial property, we're right here to assist. Search and browse our commercial property section. Possess not less than 3 years of working expertise below a Singapore licensed real-property agency; Sale, letting and property administration and taxation companies. three Shenton Means, #10-08 Shenton Home, Singapore 068805. Real property agents for purchasing, promoting, leasing, and renting property. Caveat Search

Firstly, the events might take into account to rescind the sale and buy agreement altogether. This avenue places the contracting events to a position as if the contract didn't happen. It's as if the contract was terminated from the start and events are put back into place that they were before the contract. Any items or monies handed are returned to the respective original house owners. As the worldwide real property market turns into extra refined and worldwide real property investments will increase, the ERA real estate network is well equipped to offer professional recommendation and guidance to our shoppers in making critical actual estate decisions. Relocationg, leasing and sales of properties for housing, food and beverage, retail and workplace wants.

Pasir Panjang, Singapore - $5,000-6,000 per 30 days By likelihood one among our buddies here in Singapore is an agent and we made contact for her to help us locate an residence, which she did. days from the date of execution if the doc is signed in Singapore; Be a Singapore Citizen or PR (Permanent Resident); The regulations also prohibit property agents from referring their shoppers to moneylenders, to discourage irresponsible shopping for. Brokers are additionally prohibited from holding or dealing with money on behalf of any party in relation to the sale or purchase of any property situated in Singapore, and the lease of HDB property. - Negotiate To Close A Sale together with sale and lease of HDB and private properties) Preparing your house for sale FEATURED COMMERCIAL AGENTS Property Guides

i) registered as a patent agent or its equal in any nation or territory, or by a patent workplace, specified within the Fourth Schedule; The business-specific tips for the true property agency and telecommunication sectors have been crafted to address considerations about scenarios that particularly apply to the two sectors, the PDPC stated. Mr Steven Tan, Managing Director of OrangeTee real property company, nonetheless, felt that it was a matter of "practising until it becomes part of our knowledge". "After a while, the agents ought to know the spirit behind the (Act)," he stated. Rising office sector leads real property market efficiency, while prime retail and enterprise park segments moderate and residential sector continues in decline Please choose an attendee for donation. A projective plane is defined axiomatically as an incidence structure, in terms of a set P of points, a set L of lines, and an incidence relation I that determines which points lie on which lines. As P and L are only sets one can interchange their roles and define a plane dual structure.

By interchanging the role of "points" and "lines" in

C=(P,L,I)

we obtain the dual structure

C* =(L,P,I*),

where I* is the inverse relation of I.

In a projective plane a statement involving points, lines and incidence between them that is obtained from another such statement by interchanging the words "point" and "line" and making whatever grammatical adjustments that are necessary, is called the plane dual statement of the first. The plane dual statement of "Two points are on a unique line." is "Two lines meet at a unique point." Forming the plane dual of a statement is known as dualizing the statement.

If a statement is true in a projective plane C, then the plane dual of that statement must be true in the dual plane C*. This follows since dualizing each statement in the proof "in C" gives a statement of the proof "in C*."

In the projective plane C, it can be shown that there exist four lines, no three of which are concurrent. Dualizing this theorem and the first two axioms in the definition of a projective plane shows that the plane dual structure C* is also a projective plane, called the dual plane of C.

If C and C* are isomorphic, then C is called self-dual. The projective planes PG(2,K) for any division ring K are self-dual. However, there are non-Desarguesian planes which are not self-dual, such as the Hall planes and some that are, such as the Hughes planes.

The Principle of Plane Duality says that dualizing any theorem in a self-dual projective plane C produces another theorem valid in C.

Correlations

Mining Engineer (Excluding Oil ) Truman from Alma, loves to spend time knotting, largest property developers in singapore developers in singapore and stamp collecting. Recently had a family visit to Urnes Stave Church. A duality is a map from a projective plane C = (P, L, I) to its dual plane C* = (L, P, I*) (see above) which preserves incidence. That is, a duality σ will map points to lines and lines to points (Pσ = L and Lσ = P) in such a way that if a point Q is on a line m (denoted by Q I m) then Qσ I* mσmσ I Qσ. A duality which is an isomorphism is called a correlation.[8] If a correlation exists then the projective plane C is self-dual.

In the special case that the projective plane is of the PG(2,K) type, with K a division ring, a duality is called a reciprocity.[9] These planes are always self-dual. By the fundamental theorem of projective geometry a reciprocity is the composition of an automorphic function of K and a homography. If the automorphism involved is the identity, then the reciprocity is called a projective correlation.

A correlation of order two (an involution) is called a polarity. If a correlation φ is not a polarity then φ2 is a nontrivial collineation.

Finite projective planes

It can be shown that a projective plane has the same number of lines as it has points (infinite or finite). Thus, for every finite projective plane there is an integer N ≥ 2 such that the plane has

N2 + N + 1 points,
N2 + N + 1 lines,
N + 1 points on each line, and
N + 1 lines through each point.

The number N is called the order of the projective plane. (See also the article on finite geometry.)

Using the vector space construction with finite fields there exists a projective plane of order N = pn, for each prime power pn. In fact, for all known finite projective planes, the order N is a prime power.

The existence of finite projective planes of other orders is an open question. The only general restriction known on the order is the Bruck-Ryser-Chowla theorem that if the order N is congruent to 1 or 2 mod 4, it must be the sum of two squares. This rules out N = 6. The next case N = 10 has been ruled out by massive computer calculations. Nothing more is known; in particular, the question of whether there exists a finite projective plane of order N = 12 is still open.

Another longstanding open problem is whether there exist finite projective planes of prime order which are not finite field planes (equivalently, whether there exists a non-Desarguesian projective plane of prime order).

A projective plane of order N is a Steiner S(2, N + 1, N2 + N + 1) system (see Steiner system). Conversely, one can prove that all Steiner systems of this form (λ = 2) are projective planes.

The number of mutually orthogonal Latin squares of order N is at most N − 1. N − 1 exist if and only if there is a projective plane of order N.

While the classification of all projective planes is far from complete, results are known for small orders:

  • 2 : all isomorphic with PG(2,2)
  • 3 : all isomorphic with PG(2,3)
  • 4 : all isomorphic with PG(2,4)
  • 5 : all isomorphic with PG(2,5)
  • 6 : impossible as the order of a projective plane, proved by Tarry who showed that Euler's thirty-six officers problem has no solution
  • 7 : all isomorphic with PG(2,7)
  • 8 : all isomorphic with PG(2,8)
  • 9 : PG(2,9), and three more different (non-isomorphic) non-Desarguesian planes. (All described in Template:Harv).
  • 10 : impossible as an order of a projective plane, proved by heavy computer calculation.[10]
  • 11 : at least PG(2,11), others are not known but possible.
  • 12 : it is conjectured to be impossible as an order of a projective plane.

Projective planes in higher dimensional projective spaces

Projective planes may be thought of as projective geometries of "geometric" dimension two.[11] Higher dimensional projective geometries can be defined in terms of incidence relations in a manner analogous to the definition of a projective plane. These turn out to be "tamer" than the projective planes since the extra degrees of freedom permit Desargues' theorem to be proved geometrically in the higher dimensional geometry. This means that the coordinate "ring" associated to the geometry must be a division ring (skewfield) K, and the projective geometry is isomorphic to the one constructed from the vector space Kd+1, i.e. PG(d,K). As in the construction given earlier, the points of the d-dimensional projective space PG(d,K) are the lines through the origin in Kd + 1 and a line in PG(d,K) corresponds to a plane through the origin in Kd + 1. In fact, each i-dimensional object in PG(d,K), with i < d, is an (i+1)-dimensional (algebraic) vector subspace of Kd + 1 ("goes through the origin"). The projective spaces in turn generalize to the Grassmannian spaces.

It can be shown that if Desargues' theorem holds in a projective space of dimension greater than two, then it must also hold in all planes that are contained in that space. Since there are projective planes in which Desargues' theorem fails (non-Desarguesian planes), these planes can not be embedded in a higher dimensional projective space. Only the planes from the vector space construction PG(2,K) can appear in projective spaces of higher dimension. Some disciplines in mathematics restrict the meaning of projective plane to only this type of projective plane since otherwise general statements about projective spaces would always have to mention the exceptions when the geometric dimension is two.[12]

See also

Notes

43 year old Petroleum Engineer Harry from Deep River, usually spends time with hobbies and interests like renting movies, property developers in singapore new condominium and vehicle racing. Constantly enjoys going to destinations like Camino Real de Tierra Adentro.

References

  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Lindner, Charles C. and Christopher A. Rodger (eds.) Design Theory, CRC-Press; 1 edition (October 31, 1997). ISBN 0-8493-3986-3.
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010

External links

  1. In a more formal version of the definition it is pointed out that the terms point, line and incidence are primitive notions (undefined terms). This formal viewpoint is needed to understand the concept of duality when applied to projective planes.
  2. 2.0 2.1 Baez (2002).
  3. The real projective plane appears 37 times in the index of Bredon (1993), for example.
  4. The projective planes over fields are used throughout Shafarevich (1994), for example.
  5. David Hilbert proved the more difficult "only if" part of this result.
  6. Geometers tend to like writing mappings in an exponential notation, so Pσ means σ(P) in a more conventional notation.
  7. The points are viewed as row vectors, so to make the matrix multiplication work in this expression, the point x must be written as a column vector.
  8. Template:Harv pg.151.
  9. Template:Harv pg.94.
  10. Template:Harv
  11. There are competing notions of dimension in geometry and algebra (vector spaces). In geometry, lines are 1 dimensional, planes are 2 dimensional, solids are 3 dimensional, etc. In a vector space however, the dimension is the number of vectors in a basis. When geometries are constructed from vector spaces, these two notions of dimension can lead to confusion, so it is often the case that the geometric concept is called geometric or projective dimension and the other is algebraic or vector space dimension. The two concepts are numerically related by: algebraic dimension = geometric dimension + 1.
  12. "One might say, with some justice, that projective geometry, in so far as present day research is concerned, has split into two quite separate fields. On the one hand, the researcher into the foundations of geometry tends to regard Desarguesian spaces as completely known. Since the only possible non-Desarguesian spaces are planes, his attention is restricted to the theory of projective planes, especially the non- Desarguesian planes. On the other hand stand all those researchers - and especially, the algebraic geometers - who are unwilling to be bound to two-dimensional space and uninterested in permitting non-Desarguesian planes to assume an exceptional role in their theorems. For the latter group of researchers, there are no projective spaces except the Desarguesian spaces." Template:Harv