proposition: Fact hfs_pos_inj n p q : @hfs_pos n p = hfs_pos q -> p = q.
proof: Proof. unfold hfs_pos. rewrite bt_cls_equiv. apply pos2bt_inj. 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)