map(R,m)
i1 : R = QQ[a..d];
i2 : S = QQ[s,t];
i3 : F = map(R,matrix{{s^4,s^3*t,s*t^3,t^4}}) 4 3 3 4 o3 = map (S, R, {s , s t, s*t , t }) o3 : RingMap S <-- R
i4 : kernel F 3 2 2 2 3 2 o4 = ideal (b*c - a*d, c - b*d , a*c - b d, b - a c) o4 : Ideal of R