Fibered knot

From formulasearchengine
Revision as of 20:47, 6 November 2013 by en>Jebanks (references added)
Jump to navigation Jump to search

People are nonetheless rushing to buy properties in Singapore. A new residential condominium mission in Bedok had a long queue three days before its official launch and bought more than 350 units on the very first day. Nonetheless, there is a ‘development' that had emerged in 2011 that the majority have possibly overlooked.

In August, more than a hundred individuals across 16 states reportedly had been sickened with salmonella after consuming mangos In September, the Meals and Drug Administration detained mango imports from a Mexican packing house after the fruits had been linked to the sickenings Save Cash On Your Online Purchasing Make saving money when purchasing on-line a breeze with Bodge's favourite app, Invisible Hands. This helpful program does the price-checking analysis for you, and will warn you when a unique site has a better value - or let you realize that you have found the most effective deal. Watch Posted by Edison Foo September 29, 2013 HEARTH SALE!!! From only $9xx,000! We hope this listing will help launch your search for new properties in Singapore. It's unlawful to purchase ice cream after 6 pm, in Newark.

for a borrower with one or more excellent residential property loans3; and No SSD will be payable by the seller if the property is bought more than three years after it was bought. Non-extension of the Jan 2009 Funds assistance measures for the property market when the measures expire. Permitting up to 2 years of property tax deferral for land accepted for improvement. Lively secondary marketplace for easy exit of property investments. Curiosity on mortgage fee is tax deductible when the property is rented out. We've progressive property tax rates for residential properties- the higher the value of the residential property, the upper the tax charge. Why do I've to pay property tax on my house when I'm an onwer-occupier and not deriving rental earnings? Palacio Cluster Landed

After obtaining a Sale License (topic to authorities circumstances meant to guard individuals shopping for property in Singapore), he might www.rmmonline.com proceed to sell units in his growth. Funding in the property market of Singapore is likely one of the few investment choices the place utilizing the bank's cash could not be any easier. The power of expats, to make a down payment, leverage the capital and consequently improve total return on investment, is excessive in Singapore. PRs who own a HDB flat must sell their flat inside six months of buying a non-public residential property in Singapore. EVERLASTING residents (PRs) now face unprecedented limits on their skill to purchase property in Singapore. New Condo in 2013 March Foreigners are eligible for Singapore greenback mortgage loan. housing grant

Skilled property brokers in Singapore will assist the client and defend their interests throughout the acquisition, and will help safe the provide at the best possible price. The agents may even be sure that all paperwork are in order and that the vendor is the rightful proprietor of the property. Most of the property brokers share their databases with each other. Tuesday's measures come after the Monetary Authority of Singapore in June tightened rules on property loans, and closed loopholes that allowed some householders to circumvent loan restrictions and avoid paying levies when buying extra property. Contact us for a FREE housing loan analysis and to study concerning the newest mortgage to worth on Singapore housing loans. J Gateway Condominium (Bought Out) Oct, 2013

6. Completion of automotive park, roads and drains serving the housing project 5% 7. Notice of Vacant Possession (Upon obtaining Temporary Occupation Permit) The estimates given by SingaporeHousingLoan.SG's calculator are not quotations and are usually not binding in any way on SingaporeHousingLoan.sg or the consumer. The method of calculation does not exactly mirror that of which is being used by the individual monetary establishment and the data provided should be used as a information only. SingaporeHousingLoan.SG's calculator does not pre-qualify you for any housing loan from any monetary institution. Undercover Report Finds Unlawful Rat Meat Sold In London Market Unpasteurized Tempeh Linked To Salmonella Outbreak That Sickens 60 Hottest EC Launch in Sengkang!

BuyRentSingaporeProperty.com is dedicated in providing the newest residential launches, Developer's sales, new launches, resale, HIGH tasks and rental of properties in Singapore. Then there are new launch property condos in the mid-tier range. These are sometimes in the vicinity of the city fringe, in areas corresponding to Newton and Novena Tanjong Rhu. These new launch projects are popular due to their proximity to town heart, the place the enterprise and entertainment centers and all the amenities they provide, but they're usually cheaper than the City core region tasks. Why submit cheques to register for new property launches in Singapore? Riversails Apartment @ Higher Serangoon LakeVille @ Jurong Lakeside Condo by MCL Ferra Condo @ Leonie Hill Sobol sequences (also called LPτ sequences or (ts) sequences in base 2) are an example of quasi-random low-discrepancy sequences. They were first introduced by the Russian mathematician I. M. Sobol (Илья Меерович Соболь) in 1967.[1]

These sequences use a base of two to form successively finer uniform partitions of the unit interval, and then reorder the coordinates in each dimension.

Good distributions in the s-dimensional unit hypercube

Let Is = [0,1]s be the s-dimensional unit hypercube and f a real integrable function over Is. The original motivation of Sobol was to construct a sequence xn in Is so that

limn1ni=1nf(xi)=Isf

and the convergence be as fast as possible.

It is more or less clear that for the sum to converge towards the integral, the points xn should fill Is minimizing the holes. Another good property would be that the projections of xn on a lower-dimensional face of Is leave very few holes as well. Hence the homogeneous filling of Is does not qualify ; because in lower-dimensions many points will be at the same place, therefore useless for the integral estimation.

These good distributions are called (t,m,s)-nets and (t,s)-sequences in base b. To introduce them, define first an elementary s-interval in base b a subset of Is of the form

j=1s[ajbdj,aj+1bdj], where aj, dj are non-negative integers and aj<bdj for all j in {1, ...,s}

Given 2 integers 0tm, a (t,m,s)-net in base b is a sequence xn of bm points of Is such that CardP{x1,...,xbm}=bt for all elementary interval P in base b of hypervolume λ(P) = bt-m.

Given a non-negative integer t, a (t,s)-sequence in base b is an infinite sequence of points xn such that for all integers k0,mt, the sequence {xkbm,...,x(k+1)bm1} is a (t,m,s)-net in base b.

In his article, Sobol described Πτ-meshes and LPτ sequences, which are (t,m,s)-nets and (t,s)-sequences in base 2 respectively. The terms (t,m,s)-nets and (t,s)-sequences in base b (also called Niederreiter sequences) where coined in 1988 by H. Niederreiter.[2] The term Sobol sequences was introduced in late English-speaking papers in comparison with Halton, Faure and other low-discrepancy sequences.

A fast algorithm for the construction of Sobol sequences

A more efficient Gray code implementation was proposed by Antonov and Saleev.[3]

As for the generation of Sobol numbers, they are clearly aided by the use of Gray code G(n)=nn/2 instead of n for constructing the n-th point draw.

Suppose we have already generated all the Sobol sequence draws up to n − 1, and kept in memory the values xn−1,j for all the required dimensions. Since the Gray code G(n) differs from that of the preceding one G(n − 1) by just a single, say the k-th, bit (which is a rightmost bit of n − 1), all that needs to be done is a single XOR operation for each dimension in order to propagate all of the xn−1 to xn, i.e.

xn,i=xn1,ivk,i.

Additional uniformity properties

Sobol introduced additional uniformity conditions known as property A and A’.[4]

Definition. A low-discrepancy sequence is said to satisfy Property A if for any binary segment (not an arbitrary subset) of the d-dimensional sequence of length 2d there is exactly one draw in each 2d hypercubes that result from subdividing the unit hypercube along each of its length extensions into half.

Definition. A low-discrepancy sequence is said to satisfy Property A’ if for any binary segment (not an arbitrary subset) of the d-dimensional sequence of length 4d there is exactly one draw in each 4d hypercubes that result from subdividing the unit hypercube along each of its length extensions into four equal parts.

There are mathematical conditions that guarantee properties A and A'.

Theorem. The d-dimensional Sobol sequence possesses Property A iff

det(Vd)1(mod2),

where Vd is the d × d binary matrix defined by

Vd:=(v1,1,1v2,1,1vd,1,1v1,2,1v2,2,1vd,2,1v1,d,1v2,d,1vd,d,1),

with vk,j,m denoting the m-th digit after the binary point of the direction number vk,j = (0.vk,j,1vk,j,2 . . .)2.

Theorem. The d-dimensional Sobol sequence possesses Property A' iff

det(Ud)1mod2,

where Ud is the 2d × 2d binary matrix defined by

Ud:=(v1,1,1v1,1,2v2,1,1v2,1,2vd,1,1vd,1,2v1,2,1v1,2,2v2,2,1v2,2,2vd,2,1vd,2,2v1,2d,1v1,2d,2v2,2d,1v2,2d,2vd,2d,1vd,2d,2),

with vk,j,m denoting the m-th digit after the binary point of the direction number vk,j = (0.vk,j,1vk,j,2 . . .)2.

Tests for properties A and A’ are independent. Thus it is possible to construct the Sobol sequence which satisfies both properties A and A’ or only one of them.

The initialization of Sobol numbers

To construct a Sobol sequence a set of direction numbers vi,j needs to be selected. There is some freedom in the selection of initial direction numbers.[note 1] Therefore, it is possible to receive different realisations of the Sobol sequence for selected dimensions. A bad selection of initial numbers can considerably reduce the efficiency of Sobol sequences when used for computation.

Arguably the easiest choice for the initialisation numbers is just to have the l-th leftmost bit set, and all other bits to be zero, i.e. mk,j = 1 for all k and j. This initialisation is usually called unit initialisation. However, such a sequence fails the test for Property A and A’ even for low dimensions and hence this initialisation is bad.

Implementation and availability of Sobol sequences

Good initialisation numbers for different numbers of dimensions are provided by several authors. For example, Sobol provides initialisation numbers for dimensions up to 51.[5] The same set of initialisation numbers is used by Bratley and Fox.[6]

Initialisation numbers for high dimensions are available on Joe and Kuo.[7] Peter Jäckel provides initialisation numbers up to dimension 32 in his book "Monte Carlo methods in finance".[8]

Other implementations are available as C, Fortran 77, or Fortran 90 routines in the Numerical Recipes collection of software.[9]

Finally, commercial Sobol sequence generators are available within, for example, the NAG Library,[10] or from the British-Russian Offshore Development Agency (BRODA).[11]

See also

Notes

  1. These numbers are usually called initialisation numbers

References

  1. Sobol,I.M. (1967), "Distribution of points in a cube and approximate evaluation of integrals". Zh. Vych. Mat. Mat. Fiz. 7: 784–802 (in Russian); U.S.S.R Comput. Maths. Math. Phys. 7: 86–112 (in English).
  2. Niederreiter, H. (1988). "Low-Discrepancy and Low-Dispersion Sequences", Journal of Number Theory 30: 51–70.
  3. Antonov, I.A. and Saleev, V.M. (1979) "An economic method of computing LPτ-sequences". Zh. Vych. Mat. Mat. Fiz. 19: 243–245 (in Russian); U.S.S.R Comput. Maths. Math. Phys. 19: 252–256 (in English).
  4. Sobol, I.M. (1976) "Uniformly distributed sequences with an additional uniform property". Zh. Vych. Mat. Mat. Fiz. 16: 1332–1337 (in Russian); U.S.S.R Comput. Maths. Math. Phys. 16: 236–242 (in English).
  5. Sobol, I.M. and Levitan, Y.L. (1976). "The production of points uniformly distributed in a multidimensional cube" Tech. Rep. 40, Institute of Applied Mathematics, USSR Academy of Sciences (in Russian).
  6. Bratley, P. and Fox, B. L. (1988), "Algorithm 659: Implementing Sobol’s quasirandom sequence generator". ACM Trans. Math. Software 14: 88–100.
  7. Template:Cite web
  8. Jäckel, P. (2002) "Monte Carlo methods in finance". New York: John Wiley and Sons. (ISBN 0-471-49741-X.)
  9. Press, W.H., Teukolsky, S. A., Vetterling, W. T., and Flannery, B. P. (1992) "Numerical Recipes in Fortran 77: The Art of Scientific Computing, 2nd ed." Cambridge University Press, Cambridge, U.K.
  10. Template:Cite web
  11. Template:Cite web

External links