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[helm.git] / matitaB / matita / contribs / RELATIONAL / NPlus / defs.ma

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+(**************************************************************************)
+(*       ___                                                              *)
+(*      ||M||                                                             *)
+(*      ||A||       A project by Andrea Asperti                           *)
+(*      ||T||                                                             *)
+(*      ||I||       Developers:                                           *)
+(*      ||T||         The HELM team.                                      *)
+(*      ||A||         http://helm.cs.unibo.it                             *)
+(*      \   /                                                             *)
+(*       \ /        This file is distributed under the terms of the       *)
+(*        v         GNU General Public License Version 2                  *)
+(*                                                                        *)
+(**************************************************************************)
+
+
+
+include "datatypes/Nat.ma".
+
+inductive NPlus (p:Nat): Nat → Nat → Prop ≝
+   | nplus_zero_2: NPlus p zero p
+   | nplus_succ_2: ∀q, r. NPlus p q r → NPlus p (succ q) (succ r).
+
+interpretation "natural plus predicate" 'rel_plus x y z = (NPlus x y z).
+
+notation "hvbox(a break ⊕ b break ≍ c)"
+  non associative with precedence 45
+for @{'rel_plus $a $b $c}.