Changeset 4a54b7 in git for Singular/LIB/ratgb.lib


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Timestamp:
Oct 13, 2010, 2:37:12 PM (14 years ago)
Author:
Hans Schoenemann <hannes@…>
Branches:
(u'fieker-DuVal', '117eb8c30fc9e991c4decca4832b1d19036c4c65')(u'spielwiese', 'd08f5f0bb3329b8ca19f23b74cb1473686415c3a')
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9c5f5282789f1d596251d632f870343d23c5e7c0
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e82bb379fa5d86aee55251282d46ad9638fa2ebc
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git-svn-id: file:///usr/local/Singular/svn/trunk@13467 2c84dea3-7e68-4137-9b89-c4e89433aadc
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  • Singular/LIB/ratgb.lib

    re82bb37 r4a54b7  
    1010The operators are usually denoted by @code{d1,..,dM}.
    1111
    12 Assume, that A is a @code{G}-algebra, then the set @code{S=R-{0}} is multiplicatively 
     12Assume, that A is a @code{G}-algebra, then the set @code{S=R-{0}} is multiplicatively
    1313closed Ore set in A.
    1414That is, for any s in S and a in A, there exist t in S and b in A, such that @code{sa=bt}.
    15 In other words, one can transform any left fraction into the right fraction. 
     15In other words, one can transform any left fraction into the right fraction.
    1616The algebra @code{A_S} is called an Ore localization of A with respect to S.
    1717
    18 This library provides Groebner basis procedure for A_S, performing polynomial (that is 
     18This library provides Groebner basis procedure for A_S, performing polynomial (that is
    1919fraction-free) computations only. Note, that there is ongoing development of the
    2020subsystem called Singular:Locapal, which will provide yet another approach to Groebner
     
    2424We will assume that the variables @code{x1,...,xN} from above (which will become invertible
    2525in the localization) come as the first block in the basering.
    26 Moreover, the ordering on the basering must be an antiblock ordering, that is its 
     26Moreover, the ordering on the basering must be an antiblock ordering, that is its
    2727matrix form has the left upper @code{NxN} block zero. Here is a recipy to create such
    2828an ordering easily: use 'a(w)' definitions of the ordering N times with intvecs @code{w_i}
     
    3131
    3232Guide: with this library, it is possible
    33 - to compute a Groebner basis of an ideal or a submodule in the 'rational' 
    34   Ore localization D = A_S 
     33- to compute a Groebner basis of an ideal or a submodule in the 'rational'
     34  Ore localization D = A_S
    3535- to compute a dimension of associated graded submodule (called D-dimension)
    36 - to compute a vector space dimension over Quot(R) of a submodule of 
     36- to compute a vector space dimension over Quot(R) of a submodule of
    3737  D-dimension 0 (so called D-finite submodule)
    3838- to compute a basis over Quot(R) of a D-finite submodule
     
    8888ASSUME: the variables of basering are organized in two blocks and
    8989- the first block of length n contains the elements with respect to which one localizes,
    90 - the basering is equipped with the elimination block ordering for the variables 
     90- the basering is equipped with the elimination block ordering for the variables
    9191  in the second block
    9292NOTE: the output ring C is commutative. The ideal @code{rGBid} in C
     
    359359  // this ordering is an antiblock ordering, as it must be
    360360  def S = Weyl(); setring S;
    361   // the ideal I below annihilates parametric Appel F4 function 
     361  // the ideal I below annihilates parametric Appel F4 function
    362362  // where we set parameters to a=-2, b=-1 and d=0
    363363  ideal I =
     
    464464  // this ordering is an antiblock ordering, as it must be
    465465  def S = Weyl(); setring S;
    466   // the ideal I below annihilates parametric Appel F4 function 
     466  // the ideal I below annihilates parametric Appel F4 function
    467467  // where we set parameters to a=-2, b=-1 and d=0
    468468  ideal I =
     
    470470    y*Dy*(y*Dy-1) - y*(x*Dx+y*Dy-2)*(x*Dx+y*Dy-1);
    471471
    472   // the ideal J below annihilates parametric Appel F4 function 
     472  // the ideal J below annihilates parametric Appel F4 function
    473473  // where we set parameters to a=0, b=-1, c=0, d=0
    474474
    475   ideal J = 
     475  ideal J =
    476476    x*Dx*(x*Dx-1) - x*(x*Dx+y*Dy)*(x*Dx+y*Dy-1),
    477477    y*Dy*(y*Dy-1) - y*(x*Dx+y*Dy)*(x*Dx+y*Dy-1);
     
    479479  module M = I*gen(1), J*gen(2);
    480480
    481 // harder modification: M = M, Dx*gen(1) + Dy*gen(2); 
     481// harder modification: M = M, Dx*gen(1) + Dy*gen(2);
    482482// gives K(x,y)-dim 3
    483483
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