ring r = 0, (x, y), ds;
ideal I = x2-y3;
qring q = groebner(I);
ideal U1 = x2, xy2;
ideal U2 = xy2, y3;
groebner(U2);
option("redSB");
groebner(U2);
std(U2);
reduce(U1, groebner(U2));