X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fbasic_2%2Fgrammar%2Fitem.ma;h=97207c56c51a0e775765a0e0665ab29df7951662;hb=c60524dec7ace912c416a90d6b926bee8553250b;hp=99260ba797a31f4337c78d4782a4aeb490a76621;hpb=f10cfe417b6b8ec1c7ac85c6ecf5fb1b3fdf37db;p=helm.git

diff --git a/matita/matita/contribs/lambdadelta/basic_2/grammar/item.ma b/matita/matita/contribs/lambdadelta/basic_2/grammar/item.ma
index 99260ba79..97207c56c 100644
--- a/matita/matita/contribs/lambdadelta/basic_2/grammar/item.ma
+++ b/matita/matita/contribs/lambdadelta/basic_2/grammar/item.ma
@@ -42,6 +42,12 @@ inductive item2: Type[0] ≝
   | Flat2: flat2 → item2        (* non-binding item *)
 .
 
+(* Basic inversion lemmas ***************************************************)
+
+fact destruct_sort_sort_aux: ∀k1,k2. Sort k1 = Sort k2 → k1 = k2.
+#k1 #k2 #H destruct //
+qed-.
+
 (* Basic properties *********************************************************)
 
 lemma eq_item0_dec: ∀I1,I2:item0. Decidable (I1 = I2).