Cosmic neutrino background: Difference between revisions

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The writer is called Irwin Wunder but it's not the most masucline title out there. To collect cash is what his family and him enjoy. South Dakota is exactly where I've always been residing. Bookkeeping is my profession.<br><br>my weblog; [http://nemoonehfilm.ir/index.php?do=/profile-6876/info/ http://nemoonehfilm.ir]
:''See [[Artin–Schreier theorem]] for theory about [[real-closed field]]s.''
 
In [[mathematics]], '''Artin–Schreier theory''' is a branch of [[Galois theory]], and more specifically is a positive [[characteristic (algebra)|characteristic]] analogue of [[Kummer theory]], for Galois [[Field extension|extensions]] of degree equal to the characteristic ''p''. {{harvs|txt|author1-link=Emil Artin|author2-link=Otto Schreier|last1=Artin|last2=Schreier|year=1927}} introduced Artin–Schreier theory for extensions of prime degree ''p'', and {{harvs|txt|authorlink=Ernst Witt|last=Witt|year=1936}} generalized it to extensions of prime power degree ''p''<sup>''n''</sup>.
 
If ''K'' is a [[field (mathematics)|field]] of characteristic ''p'', a [[prime number]], any [[polynomial]] of the form
 
:<math>X^p - X + \alpha,\,</math>
 
for <math>\alpha</math> in ''K'', is called an ''Artin–Schreier polynomial''. When <math>\alpha</math> does not lie in the subset <math> \{ y \in K \, | \, y=x^p-x \; \mbox{for } x \in K \}</math>, this polynomial is [[irreducible]] in ''K''[''X''], and its [[splitting field]] over ''K'' is a [[cyclic extension]] of ''K'' of degree ''p''. This follows since for any root β, the numbers β + i, for <math>1\le i\le p</math>, form all the roots—by [[Fermat's little theorem]]—so the splitting field is <math> K(\beta) </math>.
 
Conversely, any Galois extension of ''K'' of degree ''p''  equal to the characteristic of ''K'' is the splitting field of an Artin–Schreier polynomial. This can be proved using additive counterparts of the methods involved in [[Kummer theory]], such as [[Hilbert's theorem 90]] and additive [[Galois cohomology]].  These extensions are called ''Artin–Schreier extensions''.
 
Artin–Schreier extensions play a role in the theory of [[solvability by radicals]], in characteristic ''p'', representing one of the possible classes of extensions in a solvable chain.
 
They also play a part in the theory of [[abelian varieties]] and their [[isogeny|isogenies]]. In characteristic ''p'', an isogeny of degree ''p'' of abelian varieties must, for their function fields, give either an Artin–Schreier extension or a [[purely inseparable extension]].
 
==Artin–Schreier–Witt extensions==
 
There is an analogue of Artin–Schreier theory which describes cyclic extensions in characteristic ''p'' of ''p''-power degree (not just degree ''p'' itself), using
[[Witt vector]]s,  developed by {{harvs|txt|authorlink=Ernst Witt|last=Witt|year=1936}}.
 
==References==
 
*{{Citation | last1=Artin | first1=Emil | author1-link=Emil Artin | last2=Schreier | first2=Otto | author2-link=Otto Schreier | title=Eine Kennzeichnung der reell abgeschlossenen Körper | publisher=Springer Berlin / Heidelberg | year=1927 | journal=Abhandlungen aus dem Mathematischen Seminar der Universität Hamburg | issn=0025-5858 | volume=5 | pages=225–231 | doi=10.1007/BF02952522}}
* {{Lang Algebra|edition=3r}} Section VI.6
* {{Neukirch et al. CNF}} Section VI.1
* {{Citation | url=http://www.digizeitschriften.de/main/dms/img/?IDDOC=504725 | last1=Witt | first1=Ernst | author1-link = Ernst Witt | title=Zyklische Körper und Algebren der Characteristik p vom Grad p<sup>n</sup>. Struktur diskret bewerteter perfekter Körper mit vollkommenem Restklassenkörper der Charakteristik p<sup>n</sup> | language=German | year=1936 | journal=[[Journal für die reine und angewandte Mathematik]] | volume=176 | pages=126–140}}
 
{{DEFAULTSORT:Artin-Schreier theory}}
[[Category:Galois theory]]

Revision as of 23:39, 23 September 2013

See Artin–Schreier theorem for theory about real-closed fields.

In mathematics, Artin–Schreier theory is a branch of Galois theory, and more specifically is a positive characteristic analogue of Kummer theory, for Galois extensions of degree equal to the characteristic p. Template:Harvs introduced Artin–Schreier theory for extensions of prime degree p, and Template:Harvs generalized it to extensions of prime power degree pn.

If K is a field of characteristic p, a prime number, any polynomial of the form

XpX+α,

for α in K, is called an Artin–Schreier polynomial. When α does not lie in the subset {yK|y=xpxfor xK}, this polynomial is irreducible in K[X], and its splitting field over K is a cyclic extension of K of degree p. This follows since for any root β, the numbers β + i, for 1ip, form all the roots—by Fermat's little theorem—so the splitting field is K(β).

Conversely, any Galois extension of K of degree p equal to the characteristic of K is the splitting field of an Artin–Schreier polynomial. This can be proved using additive counterparts of the methods involved in Kummer theory, such as Hilbert's theorem 90 and additive Galois cohomology. These extensions are called Artin–Schreier extensions.

Artin–Schreier extensions play a role in the theory of solvability by radicals, in characteristic p, representing one of the possible classes of extensions in a solvable chain.

They also play a part in the theory of abelian varieties and their isogenies. In characteristic p, an isogeny of degree p of abelian varieties must, for their function fields, give either an Artin–Schreier extension or a purely inseparable extension.

Artin–Schreier–Witt extensions

There is an analogue of Artin–Schreier theory which describes cyclic extensions in characteristic p of p-power degree (not just degree p itself), using Witt vectors, developed by Template:Harvs.

References

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    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
  • Template:Lang Algebra Section VI.6
  • Template:Neukirch et al. CNF Section VI.1
  • 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