proposition: Fact finite_fin_eq X : finite X <-> fin (fun _ : X => True).
proof: Proof. split; intros (l & ?); exists l; firstorder. Qed.
imports: List Arith Lia Eqdep_dec Bool Undecidability.Shared.Libs.DLW.Utils(utils_tac utils_list utils_nat) Undecidability.Shared.Libs.DLW.Vec(pos vec)