Definition hprop := mpred.Definition himp := derives.Definition heq := fun p1 p2 => derives p1 p2 /\ derives p2 p1.Definition Refl_himp := derives_refl.Definition Trans_himp := derives_trans.

(* Specifications: *)
Lemma Refl_heq : Reflexive heq.
Lemma Sym_heq : Symmetric heq.
Lemma Trans_heq : Transitive heq.