Program Definition beq (s1 s2: t) : bool := R.beq s1 s2.

(* Specifications: *)
Theorem beq_spec:
forall s1 s2, beq s1 s2 = true <-> (forall x, In x s1 <-> In x s2).
Theorem beq_spec:
forall s1 s2, beq s1 s2 = true <-> (forall x, In x s1 <-> In x s2).