proposition: Fact hfs_opair_spec' p x y : p = ⟬x,y⟭ <-> exists a b, a = hfs_pair x x /\ b = hfs_pair x y /\ p = hfs_pair a b.
proof: Proof. unfold hfs_opair; split; eauto. intros (? & ? & -> & -> & ->); auto. Qed.
imports: List Arith Lia Max Wellfounded Setoid Eqdep_dec Bool Undecidability.Shared.Libs.DLW.Utils(utils_tac utils_list finite) Undecidability.Shared.Libs.DLW.Vec(pos vec) Undecidability.Shared.Libs.DLW.Wf(wf_finite wf_chains) Undecidability.FOL.TRAKHTENBROT(notations fol_ops membership btree)