proposition: Lemma cast0 (f: {ffun 'I_k -> 'I_l}) : size (enum (codom f)) = #|codom f|.
proof: Proof. by rewrite cardE. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq path) mathcomp(ssralg fintype perm choice finfun) mathcomp(matrix bigop zmodp mxalgebra fingroup) minor