ring R=0,(x,y,z),ds;
ideal I=x+y2+z3,x+y+xyz;

matrix J = jacob(I);

print(J);
//->1,   2y,  3z2,
//->1+yz,1+xz,xy  

print(subst(J,x,0,y,0,z,0));

//->1,0,0,
//->1,1,0 

dim(std(I));
//->1

ideal K=std(I+ideal(z));
K;

//->K[1]=x
//->K[2]=y
//->K[3]=z