Singular

LIB "gradedModules.lib";
ring r;
module P=grobj(module([xy,0,xz]),intvec(0,1,0));
grview(P);
==> Graded homomorphism: r + r(-1) + r <- r(-2), given by a matrix, with degr\
   ees: 
==>      ..1 ....
==>      --- +...
==>   0 :  2 |..1
==>   1 :  - |..2
==>   0 :  2 |..3
==>      ===     
==>        2     
module D=grobj(module([y,0,z],[x2+y2,z,0]),intvec(0,1,0));
grview(D);
==> Graded homomorphism: r + r(-1) + r <- r(-1) + r(-2), given by a matrix, w\
   ith degrees: 
==>      ..1 ..2 ....
==>      --- --- +...
==>   0 :  1   2 |..1
==>   1 :  -   1 |..2
==>   0 :  1   - |..3
==>      === ===     
==>        1   2     
module PP = grpres(P);
grview(PP);
==> Graded homomorphism: r(-2) <- 0, given by zero (1 x 0) matrix.
module DD = grpres(D);
grview(DD);
==> Graded homomorphism: r(-1) + r(-2) <- 0, given by zero (2 x 0) matrix.
def T=grlifting2(DD,PP); T;
==> T[1]=0
==> T[2]=-5361*gen(1)
// def Z=grlifting2(P,D); Z; // WRONG!!!