proposition: Lemma fproperEcard A B : (A `<` B) = (A `<=` B) && (#|` A| < #|` B|)%N.
proof: Proof. by rewrite fproperEneq ltnNge andbC eqEfcard; case: (A `<=` B). Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop)