Gröbner basis of ZZ is not unique

[mohamed.barakat@…]

I would except a GB with coefficients in ZZ (with tail reduction turned) on to be unique. However:

option(redSB); ring R = (integer),(x,y),dp; matrix m[1][2] = 2*x-1, y^{2+x-2*y; matrix n[1][2] = 2*x-1, y}2+7*x-2*y-3; print(lift(m,n));

1,3, 0,1

print(lift(n,m));

1,-3, 0,1

m == std(m);

1

n == std(n);

1

[hannes]

was already fixed (tested with 4-1-2)