proposition: Lemma mem_remove_same_inv : forall x l, mem x (remove x l) -> False.
proof: Proof. Proof using. introv E. lets: mem_remove_inv E. false*. Qed.
imports: Coq.Classes.Morphisms TLC(LibTactics LibLogic LibReflect LibOperation LibProd LibOption LibNat LibInt LibWf LibMonoid LibRelation)