X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;ds=inline;f=matita%2Fmatita%2Fcontribs%2Flambda_delta%2FBasic_2%2Funfold%2Fgr2_gr2.ma;h=438605e85cf190dd93f2fffa29e8930fef46125e;hb=16bbb2d6b16d5647d944f18f0fd6d4dd3df431fe;hp=dd2d34d079d6ac6eb410d6bbe505c9ecbc0752e0;hpb=d833e40ce45e301a01ddd9ea66c29fb2b34bb685;p=helm.git

diff --git a/matita/matita/contribs/lambda_delta/Basic_2/unfold/gr2_gr2.ma b/matita/matita/contribs/lambda_delta/Basic_2/unfold/gr2_gr2.ma
index dd2d34d07..438605e85 100644
--- a/matita/matita/contribs/lambda_delta/Basic_2/unfold/gr2_gr2.ma
+++ b/matita/matita/contribs/lambda_delta/Basic_2/unfold/gr2_gr2.ma
@@ -18,4 +18,12 @@ include "Basic_2/unfold/gr2.ma".
 
 (* Main properties **********************************************************)
 
-axiom at_mono: ∀des,i,i1. @[i] des ≡ i1 → ∀i2. @[i] des ≡ i2 → i1 = i2. 
+theorem at_mono: ∀des,i,i1. @[i] des ≡ i1 → ∀i2. @[i] des ≡ i2 → i1 = i2.
+#des #i #i1 #H elim H -des -i -i1
+[ #i #x #H <(at_inv_nil … H) -x //
+| #des #d #e #i #i1 #Hid #_ #IHi1 #x #H
+  lapply (at_inv_cons_lt … H Hid) -H -Hid /2 width=1/
+| #des #d #e #i #i1 #Hdi #_ #IHi1 #x #H
+  lapply (at_inv_cons_ge … H Hdi) -H -Hdi /2 width=1/
+]
+qed-.