leadTerm(Ideal) -- get the ideal of greatest terms

i1 : R = QQ[a..d];

i2 : I = ideal(a*b-c*d, a*c-b*d)

o2 = ideal (a*b - c*d, a*c - b*d)

o2 : Ideal of R

i3 : leadTerm I

                       2
o3 = ideal (a*c, a*b, b d)

o3 : Ideal of R

i4 : R = ZZ[a..d][x,y,z];

i5 : I = ideal(a*x-b*y, x^3, y^3, z^3)

                        3   3   3
o5 = ideal (a*x - b*y, x , y , z )

o5 : Ideal of R

i6 : leadTerm I

                  3   3   2   2     2    3
o6 = ideal (a*x, z , y , b x*y , b*x y, x )

o6 : Ideal of R