X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fground%2Farith%2Fnat_pred_succ.ma;h=4a6e23b01846b0fd7b807b095b87add5b44d060f;hb=8fe4dc148d50a0352313633bea61441bc817afbf;hp=3d79e371ebb0561e12510868a5af77df236c3868;hpb=4d232392091ee233afc26ecf3120dd5f5c6a33c8;p=helm.git

diff --git a/matita/matita/contribs/lambdadelta/ground/arith/nat_pred_succ.ma b/matita/matita/contribs/lambdadelta/ground/arith/nat_pred_succ.ma
index 3d79e371e..4a6e23b01 100644
--- a/matita/matita/contribs/lambdadelta/ground/arith/nat_pred_succ.ma
+++ b/matita/matita/contribs/lambdadelta/ground/arith/nat_pred_succ.ma
@@ -17,8 +17,27 @@ include "ground/arith/nat_pred.ma".
 
 (* PREDECESSOR FOR NON-NEGATIVE INTEGERS ************************************)
 
+(* Constructions with npsucc ************************************************)
+
+lemma pnpred_succ (n): n = pnpred (npsucc n).
+* //
+qed.
+
+lemma npsucc_pred (p): p = npsucc (pnpred p).
+* //
+qed.
+
+(* Constructions with nsucc and psucc ***************************************)
+
+lemma pnpred_psucc (p): pnpred (psucc p) = nsucc (pnpred p).
+* // qed.
+
 (* Constructions with nsucc *************************************************)
 
+lemma nsucc_pnpred (p):
+      ninj p = ↑(pnpred p).
+// qed.
+
 (*** pred_Sn pred_S *)
 lemma npred_succ (n): n = ↓↑n.
 * //