X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fmatita%2Flibrary%2Fnat%2Fbinomial.ma;fp=helm%2Fsoftware%2Fmatita%2Flibrary%2Fnat%2Fbinomial.ma;h=e7d58039a34baa3338a98f4c37c8ca459da2a49f;hb=3f5a0152427fd9a89e7239befd259d27b97aaef5;hp=1a341032032b95c317863801601446727cbd983a;hpb=d0982534aee06a30f91a06d2f3e82834b132a3d3;p=helm.git

diff --git a/helm/software/matita/library/nat/binomial.ma b/helm/software/matita/library/nat/binomial.ma
index 1a3410320..e7d58039a 100644
--- a/helm/software/matita/library/nat/binomial.ma
+++ b/helm/software/matita/library/nat/binomial.ma
@@ -248,4 +248,15 @@ apply eq_sigma_p;intros
    rewrite < times_n_SO.
    reflexivity
   ]
-qed.
\ No newline at end of file
+qed.
+
+theorem exp_Sn_SSO: \forall n. exp (S n) 2 = S((exp n 2) + 2*n).
+intros.simplify.
+rewrite < times_n_SO.
+rewrite < plus_n_O.
+rewrite < sym_times.simplify.
+rewrite < assoc_plus.
+rewrite < sym_plus.
+reflexivity.
+qed.
+