- nat: some additions, plus_minus_commutative renamed plus_minus_associative

[helm.git] / matita / matita / lib / lambda / levels / term.ma

diff --git a/matita/matita/lib/lambda/levels/term.ma b/matita/matita/lib/lambda/levels/term.ma
new file mode 100644 (file)
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+++ b/matita/matita/lib/lambda/levels/term.ma
@@ -0,0 +1,37 @@
+(**************************************************************************)
+(*       ___                                                              *)
+(*      ||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 "lambda/background/preamble.ma".
+
+(* PER LEVEL TERM STRUCTURE *************************************************)
+
+(* Policy: term metavariables          : A, B, C, D, M, N
+           relative level metavariables: i, j
+           absolute level metavariables: d, e
+*)
+(* Bote: first argument: relative level of the term *)
+inductive lterm: Type[0] ≝
+| LVRef: nat  → nat  → lterm          (* variable reference by level *)
+| LAppl: nat  → lterm → lterm → lterm (* function application        *)
+.
+
+interpretation "stratified term construction (variable reference by level)"
+   'VariableReferenceByLevel i d = (LVRef i d).
+
+interpretation "stratified term construction (application)"
+   'Application i C A = (LAppl i C A).
+
+notation "hvbox( { term 46 b } § break term 90 d )"
+ non associative with precedence 46
+ for @{ 'VariableReferenceByLevel $b $d }.