proposition: Lemma single_neq y v z : y <> z -> single y v z = Var z.
proof: Proof. intro n. unfold Def.single, Def.update. eq_dec z y. subst. tauto. refl. Qed.
imports: Coq(SetoidList Basics Morphisms) CoLoR(BoolUtil LogicUtil RelUtil VecUtil EqUtil)