Bug in factorize und elim

[bulygin]

Bei mir die folgende Probleme aufgetreten sind (3-1-0, Aug 2008).

1.) factorize

ring r=(2,a),(x,y,z),lp;minpoly=a2+a+1;
poly f=(x+z)*(x+y+z); // product of two linear functions
factorize(f); // false!
> [1]:
>    _[1]=1
>    _[2]=x2+xy+yz+z2
> [2]:
>    1,1
poly f=(x+z)*(x+y);
factorize(f); // this one is OK
> [1]:
>    _[1]=1
>    _[2]=x+z
>    _[3]=x+y
> [2]:
>    1,1,1
// this problem does not occur in char=0
ring r=0,(x,y,z),lp;
poly f=(x+z)*(x+y+z);
factorize(f);
> [1]:
>    _[1]=1
>    _[2]=x+z
>    _[3]=x+y+z
> [2]:
>    1,1,1

2.) elim

Im Help steht es niergenwo, dass id in elim(id,v) soll ein GB (SB) sein. Bei mir aber habe ich gemerkt, dass bei id und std(id) man verschiedene Outputs kriegt.

ring r=(16,a),(V(2..1),U(15..1)),lp;
ideal
sys=a^12*U(13)+a^9*U(10)+a^8*U(9)+a^6*U(7)+a^4*U(5)+a^3*U(4)+a^2*U(3)+a*U(2),
U(13)+U(10)+U(9)+U(7)+U(5)+U(4)+U(3)+U(2),
a^3*U(13)+a^6*U(10)+a^7*U(9)+a^9*U(7)+a^11*U(5)+a^12*U(4)+a^13*U(3)+a^14*U(2),
a^6*U(13)+a^12*U(10)+a^14*U(9)+a^3*U(7)+a^7*U(5)+a^9*U(4)+a^11*U(3)+a^13*U(2),
a^9*U(13)+a^3*U(10)+a^6*U(9)+a^12*U(7)+a^3*U(5)+a^6*U(4)+a^9*U(3)+a^12*U(2),
a^12*U(13)+a^9*U(10)+a^13*U(9)+a^6*U(7)+a^14*U(5)+a^3*U(4)+a^7*U(3)+a^11*U(2),
U(13)+U(10)+a^5*U(9)+U(7)+a^10*U(5)+U(4)+a^5*U(3)+a^10*U(2),
a^3*U(13)+a^6*U(10)+a^12*U(9)+a^9*U(7)+a^6*U(5)+a^12*U(4)+a^3*U(3)+a^9*U(2),
V(1)*U(1)+U(2),
V(1)*U(2)+U(3),
V(1)*U(3)+U(4),
V(1)*U(4)+U(5),
V(1)*U(5)+U(6),
V(1)*U(6)+U(7),
V(1)*U(7)+U(8),
V(1)*U(8)+U(9),
V(1)*U(9)+U(10),
V(1)*U(10)+U(11),
V(1)*U(11)+U(12),
V(1)*U(12)+U(13),
V(1)*U(13)+U(14),
V(1)*U(14)+U(15),
V(1)*U(15)+U(1);
elim(sys,1..2); // eliminate V(1) and V(2), is not correct!
> _[1]=U(1)
elim(std(sys),1..2); // now is OK
> _[1]=U(1)
> _[2]=U(2)
> _[3]=U(3)
> _[4]=U(4)
> _[5]=U(5)
> _[6]=U(6)
> _[7]=U(7)
> _[8]=U(8)
> _[9]=U(9)
> _[10]=U(10)
> _[11]=U(11)
> _[12]=U(12)
> _[13]=U(13)
> _[14]=U(14)
> _[15]=U(15)

[bulygin]

I have tried the above problem on the latest Singular from CVS. And the problems I described remain.

Singular for x86_64-Linux version 3-1-0 (3100-2009021217)  Feb 12 2009 17:27:18
with
        factory(@(#) factoryVersion = 3.1.0),libfac(3.1.0,Aug 2008),
        GMP(4.2),NTL(5.4.2),64bit,static readline,Plural,DBM,
        namespaces,dynamic modules,dynamic p_Procs,OM_CHECK=0,OM_TRACK=0,random=1234535672
        CC= gcc -O3 -w -fomit-frame-pointer -pipe -DNDEBUG -DOM_NDEBUG -Dx86_64_Linux -DHAVE_CONFIG_H,
        CXX= g++ -O3 -w -fomit-frame-pointer --no-rtti -pipe -DNDEBUG -DOM_NDEBUG -Dx86_64_Linux -DHAVE_CONFIG_H (4.1.2 (Gentoo 4.1.2 p1.3))
argv[0]   :     ./Singular
SearchPath:     /var/autofs/nfs/urmel/alggeom/bulygin/pb2/Singular/LIB:/var/autofs/nfs/urmel/alggeom/bulygin/pb2/LIB
Singular  :     /var/autofs/nfs/urmel/alggeom/bulygin/pb2/Singular/Singular
BinDir    :     /var/autofs/nfs/urmel/alggeom/bulygin/pb2/Singular
RootDir   :     /var/autofs/nfs/urmel/alggeom/bulygin/pb2
DefaultDir:     /var/autofs/nfs/urmel/alggeom/bulygin/pb2
InfoFile  :
IdxFile   :
HtmlDir   :
ManualUrl :     http://www.singular.uni-kl.de/Manual/3-1-0
ExDir     :
Path      :     /var/autofs/nfs/urmel/alggeom/bulygin/pb2/Singular:/var/autofs/nfs/urmel/alggeom/bulygin/Macaulay2-0.9.95/bin:/usr/local/bin:/usr/bin:/bin:/opt/bin:/usr/x86_64-pc-linux-gnu/gcc-bin/4.1.2:/usr/qt/3/bin
EmacsDir  :     /var/autofs/nfs/urmel/alggeom/bulygin/pb2/emacs
Available HelpBrowsers: dummy, emacs,
Current HelpBrowser: dummy
                     SINGULAR                             /  Development
 A Computer Algebra System for Polynomial Computations   /   version 3-1-0
                                                       0<
     by: G.-M. Greuel, G. Pfister, H. Schoenemann        \   Aug 2008
FB Mathematik der Universitaet, D-67653 Kaiserslautern    \
// ** executing /var/autofs/nfs/urmel/alggeom/bulygin/pb2/Singular/LIB/.singularrc

[hannes]

part 1 is ticket 2 part 2 is correct: the manual says; The result is a SB with respect to the ordering of

the second block used by elimRing.

-- this has nothing to to with being an SB in the original ring.