//SINGULAR ExampleA.2.14 LIB "algebra.lib"; ring R = 0,(x,y,z),dp; qring Q = std(z-x2+y3); //quotient ring R/ ring S = 0,(a,b,c,d),dp; map psi = R,a,a+b,c-a2+d3; //a map from R to S, //x->a, y->a+b, z->c-a2+d3 is_injective(psi,R); is_surjective(psi,R); qring T = std(ideal(d,c-a2+b3)); //quotient ring S/ map chi = Q,a,b,a2-b3; //map Q --> T between two //quotient rings, //x->a, y->b, z->a2-b3 is_bijective(chi,Q);