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(*         *   The Coq Proof Assistant / The Coq Development Team       *)
(*  v      *   INRIA, CNRS and contributors - Copyright 1999-2018       *)
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(*         *     GNU Lesser General Public License Version 2.1          *)
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(** This module states the axiom of (dependent) functional extensionality and (dependent) eta-expansion. It introduces a tactic [extensionality] to apply the axiom of extensionality to an equality goal. *)
(** The converse of functional extensionality. *)

Lemma equal_f_dep : forall {A B} {f g : forall (x : A), B x},
f = g -> forall x, f x = g x.