X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fmatita%2Fnlibrary%2Flogic%2Fequality.ma;h=2418f2a7c504da2a7f8b68957604c30ad224a4be;hb=6003ba0e4600778c6055ed5ea5cb6c1fba3abe32;hp=ff8cc5a1392c5393d997f2f85dd0da48e8397942;hpb=72aa8b2087285826b14fc39a389632f0317c51b6;p=helm.git

diff --git a/helm/software/matita/nlibrary/logic/equality.ma b/helm/software/matita/nlibrary/logic/equality.ma
index ff8cc5a13..2418f2a7c 100644
--- a/helm/software/matita/nlibrary/logic/equality.ma
+++ b/helm/software/matita/nlibrary/logic/equality.ma
@@ -16,6 +16,11 @@ include "logic/connectives.ma".
 
 ninductive eq (A: Type) (a: A) : A → CProp ≝
  refl: eq A a a.
+
+nlet rec eq_rect (A: Type) (x: A) (P: ∀y:A. eq A x y → CProp) (q: P x (refl A x))
+ (y: A) (p: eq A x y) on p : P y p ≝
+ match p with
+  [ refl ⇒ q ].
  
 interpretation "leibnitz's equality" 'eq t x y = (eq t x y).