proposition: Fact bt_tc_congr_r u s t : s ≈ t -> u ∈ ↓s <-> u ∈ ↓t.
proof: Proof. intros H; revert u. rewrite bte_incl_equiv in H; destruct H. apply bte_ext, bti_equiv; auto. Qed.
imports: List Arith Lia Max Wellfounded Setoid Eqdep_dec Undecidability.Shared.Libs.DLW.Utils(utils_tac utils_list utils_decidable finite seteq) Undecidability.Shared.Libs.DLW.Vec(pos) Undecidability.Shared.Libs.DLW.Wf(wf_finite wf_chains) Undecidability.FOL.TRAKHTENBROT(notations fol_ops)