Even more Q stuff classified.

[helm.git] / helm / software / matita / library / Z / times.ma

diff --git a/helm/software/matita/library/Z/times.ma b/helm/software/matita/library/Z/times.ma
index 90a71b520ff3fde852bb2026812af9beea519cbe..c81c0dfca85537d72f218c8c0eab8a66dfb5368a 100644 (file)
--- a/helm/software/matita/library/Z/times.ma
+++ b/helm/software/matita/library/Z/times.ma
@@ -251,3 +251,13 @@ qed.
 variant distr_Ztimes_Zplus: \forall x,y,z.
 x * (y + z) = x*y + x*z \def
 distributive_Ztimes_Zplus.
+
+theorem eq_plus_Zplus: \forall n,m:nat. Z_of_nat (n+m) =
+Z_of_nat n + Z_of_nat m.
+intro.cases n;intro
+  [reflexivity
+  |cases m
+    [simplify.rewrite < plus_n_O.reflexivity
+    |simplify.reflexivity.
+    ]]
+qed.