 LIB "ncalg.lib";
def U = makeUsl2(); // this algebra is U(sl_2)
setring U;
ideal i= e^3, f^3, h^3  4*h;
option(redSB);
option(redTail);
ideal I = std(i);
print(matrix(I)); // print a compact presentation of I
==> h34h,fh22fh,eh2+2eh,2efhh22h,f3,e3
ideal J = twostd(i);
// print a compact presentation of J:
print(matrix(ideal(J[1..6]))); // first 6 gen's
==> h34h,fh22fh,eh2+2eh,f2h2f2,2efhh22h,e2h+2e2
print(matrix(ideal(J[7..size(J)]))); // the rest of gen's
==> f3,ef2fh,e2feh2e,e3
// compute the set of elements present in J but not in I
ideal K = NF(J,I);
K = K+0; // simplify K
print(matrix(K));
==> f2h2f2,e2h+2e2,ef2fh,e2feh2e
