update in ground

+ positive integer two

diff --git a/matita/matita/contribs/lambdadelta/ground/arith/arith_2a.ma b/matita/matita/contribs/lambdadelta/ground/arith/arith_2a.ma
index 92224c4c9560d1f51b5c54e52c144fda38b2ec00..a136174bc8b209fc0c813c013b3382cdca587938 100644 (file)
--- a/matita/matita/contribs/lambdadelta/ground/arith/arith_2a.ma
+++ b/matita/matita/contribs/lambdadelta/ground/arith/arith_2a.ma
@@ -12,16 +12,12 @@
 (*                                                                        *)
 (**************************************************************************)
 
-include "ground/notation/functions/two_0.ma".
+include "ground/arith/pnat_two.ma".
 include "ground/arith/nat_le_minus_plus.ma".
 include "ground/arith/nat_lt.ma".
 
 (* ARITHMETICAL PROPERTIES FOR λδ-2A ****************************************)
 
-interpretation
-  "zero (non-negative integers)"
-  'Two = (ninj (psucc punit)).
-
 (* Equalities ***************************************************************)
 
 lemma plus_n_2: ∀n. (n + 𝟐) = n + 𝟏 + 𝟏.

diff --git a/matita/matita/contribs/lambdadelta/ground/arith/pnat_two.ma b/matita/matita/contribs/lambdadelta/ground/arith/pnat_two.ma
new file mode 100644 (file)
index 0000000..d1be445
--- /dev/null
+++ b/matita/matita/contribs/lambdadelta/ground/arith/pnat_two.ma
@@ -0,0 +1,22 @@
+(**************************************************************************)
+(*       ___                                                              *)
+(*      ||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 "ground/notation/functions/two_0.ma".
+include "ground/arith/pnat.ma".
+
+(* POSITIVE INTEGERS ********************************************************)
+
+interpretation
+  "two (positive integers)"
+  'Two = (psucc punit).