From: Andrea Asperti <andrea.asperti@unibo.it>
Date: Mon, 9 Oct 2006 11:00:31 +0000 (+0000)
Subject: The two coercions sym_eq e eq_f gives BIG TROUBLES when checking composition during
X-Git-Tag: 0.4.95@7852~923
X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=commitdiff_plain;h=a5ba8bfcd6ae3b5033e58792092924455cc51837;p=helm.git

The two coercions sym_eq e eq_f gives BIG TROUBLES when checking composition during
qed. In particular, checking composition calls unification, that calls reductions,
that is problematic when there are a lot of lein in the context (as is it the case
with proofs generated by TPTP: see eg GRP486-1.p.ma )
---

diff --git a/matita/library/logic/equality.ma b/matita/library/logic/equality.ma
index 0561fb993..3b242c667 100644
--- a/matita/library/logic/equality.ma
+++ b/matita/library/logic/equality.ma
@@ -65,8 +65,15 @@ theorem eq_f: \forall  A,B:Type.\forall f:A\to B.
 intros.elim H.apply refl_eq.
 qed.
 
+theorem eq_f': \forall  A,B:Type.\forall f:A\to B.
+\forall x,y:A. x=y \to f y = f x.
+intros.elim H.apply refl_eq.
+qed.
+
+(* 
 coercion cic:/matita/logic/equality/sym_eq.con.
 coercion cic:/matita/logic/equality/eq_f.con.
+*)
 
 default "equality"
  cic:/matita/logic/equality/eq.ind
@@ -75,7 +82,7 @@ default "equality"
  cic:/matita/logic/equality/eq_ind.con
  cic:/matita/logic/equality/eq_elim_r.con
  cic:/matita/logic/equality/eq_f.con
- cic:/matita/logic/equality/eq_OF_eq.con. (* \x.sym (eq_f x) *)
+ cic:/matita/logic/equality/eq_f'.con. (* \x.sym (eq_f x) *)
  
 theorem eq_f2: \forall  A,B,C:Type.\forall f:A\to B \to C.
 \forall x1,x2:A. \forall y1,y2:B.