substituteFace(F,R)
Substitute a face to a different ring.
i1 : K=QQ;
i2 : R=K[x_0..x_4];
i3 : F=face {x_0,x_1,x_2} o3 = x x x 0 1 2 o3 : face with 3 vertices in R
i4 : S=R**K[y] o4 = S o4 : PolynomialRing
i5 : substitute(F,S) o5 = x x x 0 1 2 o5 : face with 3 vertices in S