proposition: Lemma beq_dec_sym : forall x y, beq_dec x y = beq_dec y x.
proof: Proof. intros. unfold beq_dec. case (eq_dec x y); case (eq_dec y x); intros; (refl || cong). Qed.
imports: Coq(Structures.Equalities) CoLoR(LogicUtil RelUtil BoolUtil)