X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fmatita%2Fnlibrary%2Fnat%2Fplus.ma;h=8bbc71b9cbbbc3b5d50ece774467c69ebf890048;hb=bf7be462a06e739b39af20f72362857e849a2aa0;hp=62fe4917a3ecff80a5db88248715a0999e413653;hpb=a0c0e92cee3ed99995e12b02f18e30f018d946ea;p=helm.git

diff --git a/helm/software/matita/nlibrary/nat/plus.ma b/helm/software/matita/nlibrary/nat/plus.ma
index 62fe4917a..8bbc71b9c 100644
--- a/helm/software/matita/nlibrary/nat/plus.ma
+++ b/helm/software/matita/nlibrary/nat/plus.ma
@@ -12,18 +12,46 @@
 (*                                                                        *)
 (**************************************************************************)
 
-include "nat/nat.ma".
-include "algebra/magmas.ma".
+include "nat/big_ops.ma".
+include "algebra/unital_magmas.ma".
+include "algebra/abelian_magmas.ma".
 
 nlet rec plus (n:nat) (m:nat) on n : nat ≝
  match n with
   [ O ⇒ m
   | S n' ⇒ S (plus n' m) ].
 
+interpretation "natural plus" 'plus x y = (plus x y).
+
 ndefinition plus_magma_type: magma_type.
  napply mk_magma_type
   [ napply NAT
   | napply mk_binary_morphism
      [ napply plus
      | #a; #a'; #b; #b'; #Ha; #Hb; nrewrite < Ha; nrewrite < Hb; napply refl ]##]
-nqed.
\ No newline at end of file
+nqed.
+
+ndefinition plus_abelian_magma_type: abelian_magma_type.
+ napply mk_abelian_magma_type
+  [ napply plus_magma_type
+  | nnormalize; #x;
+     (* nelim non va *) napply (nat_rect_CProp0 ??? x);
+     ##[ #y; napply (nat_rect_CProp0 ??? y) [ napply refl | #n; #H; nnormalize; nrewrite < H; napply refl]
+     ##| #n; #H; #y; nnormalize;
+         (* rewrite qui non va *)
+         napply (eq_rect_CProp0_r ????? (H y));
+         napply (nat_rect_CProp0 ??? y)
+          [ napply refl
+          | #n0; #K; nnormalize in K; nnormalize;
+            napply (eq_rect_CProp0 ????? K); napply refl] ##]
+nqed.
+
+ndefinition plus_unital_magma_type: unital_magma_type.
+ napply mk_unital_magma_type
+  [ napply plus_magma_type
+  | napply O
+  | #x; napply refl
+  | #x; (* qua manca ancora l'hint *) napply (symm plus_abelian_magma_type) ]
+nqed.
+
+ndefinition big_plus ≝ λn.λf.big_op plus_magma_type n f O.