- revision of ground_2 and basic_2

[helm.git] / matita / matita / contribs / lambdadelta / ground_2 / ynat / ynat_pred.ma

diff --git a/matita/matita/contribs/lambdadelta/ground_2/ynat/ynat_pred.ma b/matita/matita/contribs/lambdadelta/ground_2/ynat/ynat_pred.ma
index 652b6e2193365d214fc7484bf2d009c98950dba3..1f14ea6c0c0f57522257d26b43870251eef35322 100644 (file)
--- a/matita/matita/contribs/lambdadelta/ground_2/ynat/ynat_pred.ma
+++ b/matita/matita/contribs/lambdadelta/ground_2/ynat/ynat_pred.ma
@@ -26,9 +26,13 @@ definition ypred: ynat → ynat ≝ λm. match m with
 
 interpretation "ynat predecessor" 'Predecessor m = (ypred m).
 
-(* Properties ***************************************************************)
+lemma ypred_O: ⫰0 = 0.
+// qed.
+
+lemma ypred_S: ∀m:nat. ⫰(S m) = m.
+// qed.
 
-lemma ypred_inj_rew: ∀m:nat. ⫰m = pred m.
+lemma ypred_Y: (⫰∞) = ∞.
 // qed.
 
 (* Inversion lemmas *********************************************************)