X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;ds=sidebyside;f=helm%2Fsoftware%2Fmatita%2Fcontribs%2FLAMBDA-TYPES%2FLevel-1%2FBase%2Fext%2Fpreamble.ma;h=b4c69f299f366435e7fbad576a9d2c8437580691;hb=02bd27d53c28099b9fc92917cf34ccf3bc72d696;hp=3892cb628154ce66eb78ba3434bb38b7e1a59dee;hpb=bfb39a9bcb10b87ab7d6e09928fb82d340d8feca;p=helm.git

diff --git a/helm/software/matita/contribs/LAMBDA-TYPES/Level-1/Base/ext/preamble.ma b/helm/software/matita/contribs/LAMBDA-TYPES/Level-1/Base/ext/preamble.ma
index 3892cb628..b4c69f299 100644
--- a/helm/software/matita/contribs/LAMBDA-TYPES/Level-1/Base/ext/preamble.ma
+++ b/helm/software/matita/contribs/LAMBDA-TYPES/Level-1/Base/ext/preamble.ma
@@ -138,6 +138,12 @@ theorem sym_not_eq: \forall A:Type. \forall x,y:A. x \neq y \to y \neq x.
  unfold not. intros. apply H. symmetry. assumption.
 qed.
 
+theorem trans_eq : ∀A:Type.∀x,y,z:A.x=y→y=z→x=z.
+ intros;
+ transitivity y;
+ assumption.
+qed.
+
 theorem plus_reg_l: \forall (n,m,p:nat). n + m = n + p \to m = p.
  intros. apply plus_reg_l; auto.
 qed.
@@ -146,12 +152,10 @@ theorem plus_le_reg_l: \forall p,n,m. p + n <= p + m \to n <= m.
  intros. apply plus_le_reg_l; auto.
 qed.
 
-definition sym_equal \def sym_eq.
-
 default "equality"
  cic:/Coq/Init/Logic/eq.ind
  cic:/matita/LAMBDA-TYPES/Level-1/Base/ext/preamble/sym_eq.con
- cic:/Coq/Init/Logic/trans_eq.con
+ cic:/matita/LAMBDA-TYPES/Level-1/Base/ext/preamble/trans_eq.con
  cic:/Coq/Init/Logic/eq_ind.con
  cic:/Coq/Init/Logic/eq_ind_r.con
  cic:/matita/LAMBDA-TYPES/Level-1/Base/ext/preamble/f_equal.con