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7.10.4.13 testSyz

Procedure from library freegb.lib (see freegb_lib).

Usage:
testSyz(M,S); module M, S

Return:
module

Purpose:
tests the result of the syz procedure

Assume:
S is the syzygy bimodule of M

Example:
 
LIB "freegb.lib";
ring r = 0,(x,y),(c,Dp);
ring R = freeAlgebra(r, 7, 2);
ideal I = twostd(x*y*x + 1);
print(matrix(I));
==> x*y-y*x,y*x*x+1
module S = syz(I);
print(S);
==> ncgen(1)*x*x,S[1,2],S[1,3],S[1,4],S[1,5],
==> S[2,1],      S[2,2],S[2,3],S[2,4],S[2,5] 
testSyz(I,S); // returns zero
==> _[1]=0
==> _[2]=0
==> _[3]=0
==> _[4]=0
==> _[5]=0