 ring r = (0,a),(e,f,h),(c,dp);
matrix D[3][3];
D[1,2]=h; D[1,3]=2*e; D[2,3]=2*f;
def R=nc_algebra(1,D); // this algebra is a parametric U(sl_2)
setring R;
ideal I = e,ha; // consider this parametric ideal
I = std(I); // left Groebner basis
print(matrix(I)); // print a compact presentation of I
==> h+(a),e
poly Z = 4*e*f+h^22*h; // a central element in R
Z = Z  NF(Z,I); // a central character
ideal j = std(Z);
j;
==> j[1]=4*ef+h22*h+(a22a)
matrix T = lift(I,j);
print(T);
==> h+(a+2),
==> 4*f
ideal tj = ideal(transpose(T)*transpose(matrix(I)));
size(ideal(matrix(j)matrix(tj))); // test for 0
==> 0
