Section Subst.
Context {Σ_funcs : funcs_signature}.
Context {Σ_preds : preds_signature}.
Context {ops : operators}.
End Subst.
(* ** Discreteness *)

Lemma inj_pair2_eq_dec' A :
eq_dec A -> forall (P : A -> Type) (p : A) (x y : P p), existT P p x = existT P p y -> x = y.