proposition: Lemma mulVf x : x != 0 -> x^-1 * x = 1.
proof: Proof. by rewrite -unitfE; apply: mulVr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)