Description
Given an ideal I representing a projective variety X in P^r, a positive integer k<r, and optionally a ring GR with (exactly) r+1 choose k+1 variables, representing the ambient space of the Grassmannian of k-planes in P^r, this routine returns the ideal in GR of the Fano scheme that parametrizes the k-planes lying on X. If the optional third argument is not present, the routine fabricates its own ring, and returns an ideal in it.