Hi Hans,
Since 4-1-0, I get the following
SINGULAR / Development
A Computer Algebra System for Polynomial Computations / version 4.1.0
0<
by: W. Decker, G.-M. Greuel, G. Pfister, H. Schoenemann \ Nov 2016
FB Mathematik der Universitaet, D-67653 Kaiserslautern \
> ring r = integer,(x,y,z),lp;
> r;
// coefficients: ZZ
// number of vars : 3
// block 1 : ordering lp
// : names x y z
// block 2 : ordering C
> ideal i = -y^2 - 3*y + z^2 + 3, -2*y*z + z^2 + 2*z + 1,x*z + y*z + z^2, -3*x*y + 2*y*z + 6*z^2;
> i;
i[1]=-y2-3y+z2+3
i[2]=-2yz+z2+2z+1
i[3]=xz+yz+z2
i[4]=-3xy+2yz+6z2
> groebner(i);
// ***dError: assume violation at prCopy.cc:195 condition: src_r->cf==dest_r->cf
// ***dError: assume violation at prCopy.cc:179 condition: src_r->cf==dest_r->cf!!longrat:debug:1 in pDebug.cc:253
// ***dPolyReportError: coeff err
occurred at
occurred for poly: !!longrat:im int 2 in longrat.cc:1387
#############################################
No issues with 4-0-3:
SINGULAR / Development
A Computer Algebra System for Polynomial Computations / version 4.0.3
0<
by: W. Decker, G.-M. Greuel, G. Pfister, H. Schoenemann \ Jan 2016
FB Mathematik der Universitaet, D-67653 Kaiserslautern \
> ring r = integer,(x,y,z),lp;
> deal i = -y^2 - 3*y + z^2 + 3, -2*y*z + z^2 + 2*z + 1,x*z + y*z + z^2, -3*x*y + 2*y*z + 6*z^2;
? `deal` is undefined
? error occurred in or before STDIN line 2: `3*y + z^2 + 3, -2*y*z + z^2 + 2*z + 1,x*z + y*z + z^2, -3*x*y + 2*y*z + 6*z^2;`
> ideal i = -y^2 - 3*y + z^2 + 3, -2*y*z + z^2 + 2*z + 1,x*z + y*z + z^2, -3*x*y + 2*y*z + 6*z^2;
> groebner(i);
_[1]=164878
_[2]=2z+41856
_[3]=z2-81962z-57679
_[4]=2y-3z3+10z2+5z+8
_[5]=yz+5y+72z4-259z3-120z2-231z
_[6]=y2+3y-z2-3
_[7]=x+2y2z+yz2-2yz-z3-2z2
>
###########################################
The dError stuff comes from:
*
https://github.com/Singular/Sources/blob/spielwiese/Singular/iparith.cc#L5784Indeed the coefficients are explicitly changed to n_Q.
I did not investigate this further yet.
Best,
JPF