X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fground_2%2Fynat%2Fynat_pred.ma;fp=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fground_2%2Fynat%2Fynat_pred.ma;h=8d17df7ff8daabc1b28051b450cd5135cacda97c;hb=5102e7f780e83c7fef1d3826f81dfd37ee4028bc;hp=1f14ea6c0c0f57522257d26b43870251eef35322;hpb=174ee1889b5c91ef5339c718d7657ed0e5da21e8;p=helm.git

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 1f14ea6c0..8d17df7ff 100644
--- a/matita/matita/contribs/lambdadelta/ground_2/ynat/ynat_pred.ma
+++ b/matita/matita/contribs/lambdadelta/ground_2/ynat/ynat_pred.ma
@@ -20,16 +20,16 @@ include "ground_2/ynat/ynat.ma".
 
 (* the predecessor function *)
 definition ypred: ynat → ynat ≝ λm. match m with
-[ yinj m ⇒ pred m
+[ yinj m ⇒ ⫰m
 | Y      ⇒ Y
 ].
 
 interpretation "ynat predecessor" 'Predecessor m = (ypred m).
 
-lemma ypred_O: â«°0 = 0.
+lemma ypred_O: â«°(yinj 0) = yinj 0.
 // qed.
 
-lemma ypred_S: ∀m:nat. ⫰(S m) = m.
+lemma ypred_S: ∀m:nat. ⫰(⫯m) = yinj m.
 // qed.
 
 lemma ypred_Y: (⫰∞) = ∞.
@@ -37,7 +37,7 @@ lemma ypred_Y: (⫰∞) = ∞.
 
 (* Inversion lemmas *********************************************************)
 
-lemma ypred_inv_refl: ∀m. ⫰m = m → m = 0 ∨ m = ∞.
+lemma ypred_inv_refl: ∀m:ynat. ⫰m = m → m = 0 ∨ m = ∞.
 * // #m #H lapply (yinj_inj … H) -H (**) (* destruct lemma needed *)
 /4 width=1 by pred_inv_refl, or_introl, eq_f/
 qed-.