proposition: Fact mb_is_opair_dec p x y : { p ≋ ⦅x,y⦆ } + { ~ p ≋ ⦅x,y⦆ }.
proof: Proof. Proof using Xfin Rdec. unfold mb_is_opair. do 2 (apply (fol_quant_sem_dec fol_ex); auto; intro). repeat (apply (fol_bin_sem_dec fol_conj); auto). Qed.
imports: List Arith Nat Lia Max Wellfounded Coq.Setoids.Setoid Undecidability.Shared.Libs.DLW.Utils(utils_tac utils_list finite) Undecidability.Shared.Libs.DLW.Vec(pos vec) Undecidability.FOL.TRAKHTENBROT(notations fol_ops fo_sig fo_terms fo_logic)