proposition: Lemma eqVmproper A B : A `<=` B -> A = B \/ A `<` B.
proof: Proof. by rewrite msubEproper => /predU1P. Qed.
imports: mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop tuple) finmap