proposition: Lemma noduplicates_nil_eq : noduplicates (@nil A) = True.
proof: Proof. Proof using. extens. iff M; inverts* M. Qed.
imports: Coq.Classes.Morphisms TLC(LibTactics LibLogic LibReflect LibOperation LibProd LibOption LibNat LibInt LibWf LibMonoid LibRelation)