proposition: Lemma finType_eqb_reflect (X:finType) (x y:X) : reflect (x = y) (finType_eqb x y).
proof: Proof. unfold finType_eqb. destruct (Nat.eqb_spec (index x) (index y));constructor. - now apply injective_index. - congruence. Qed.
imports: Undecidability.L.Tactics(LTactics GenEncode) Undecidability.L(Datatypes.LNat Functions.EqBool) Undecidability.Shared.Libs.PSL.FiniteTypes.FinTypes