matita/matita/contribs/lambdadelta/ground/arith/ynat_lminus_succ.ma

   1 (**************************************************************************)
   2 (*       ___                                                              *)
   3 (*      ||M||                                                             *)
   4 (*      ||A||       A project by Andrea Asperti                           *)
   5 (*      ||T||                                                             *)
   6 (*      ||I||       Developers:                                           *)
   7 (*      ||T||         The HELM team.                                      *)
   8 (*      ||A||         http://helm.cs.unibo.it                             *)
   9 (*      \   /                                                             *)
  10 (*       \ /        This file is distributed under the terms of the       *)
  11 (*        v         GNU General Public License Version 2                  *)
  12 (*                                                                        *)
  13 (**************************************************************************)
  14
  15 include "ground/arith/ynat_pred_succ.ma".
  16 include "ground/arith/ynat_lminus.ma".
  17
  18 (* LEFT SUBTRACTION FOR NON-NEGATIVE INTEGERS WITH INFINITY *****************)
  19
  20 (* Constructions with ysucc *************************************************)
  21
  22 (*** yminus_succ *)
  23 lemma ylminus_succ_bi (x:ynat) (n): x - n = ↑x - ↑n.
  24 // qed.