From 882c692d91bd56a2534ac862b8d557b529aaae54 Mon Sep 17 00:00:00 2001 From: Jasper Hugunin Date: Mon, 11 Dec 2017 12:07:47 +0900 Subject: Axiom-free proof of eta expansion. --- theories/Logic/FunctionalExtensionality.v | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'theories') diff --git a/theories/Logic/FunctionalExtensionality.v b/theories/Logic/FunctionalExtensionality.v index ac95ddd0c..82b04d132 100644 --- a/theories/Logic/FunctionalExtensionality.v +++ b/theories/Logic/FunctionalExtensionality.v @@ -221,13 +221,12 @@ Tactic Notation "extensionality" "in" hyp(H) := (* If we [subst H], things break if we already have another equation of the form [_ = H] *) destruct Heq; rename H_out into H. -(** Eta expansion follows from extensionality. *) +(** Eta expansion is built into Coq. *) Lemma eta_expansion_dep {A} {B : A -> Type} (f : forall x : A, B x) : f = fun x => f x. Proof. intros. - extensionality x. reflexivity. Qed. -- cgit v1.2.3