proposition: Fact hfs_trans_pair_inv x y : hfs_pair x y ∈ t -> x ∈ t /\ y ∈ t.
proof: Proof. Proof using Hp. intros H; split; apply Hp with (2 := H); apply hfs_pair_spec; 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)