- degree-based equivalene for terms

[helm.git] / matita / matita / contribs / lambdadelta / basic_2 / syntax / lenv_weight.ma

diff --git a/matita/matita/contribs/lambdadelta/basic_2/syntax/lenv_weight.ma b/matita/matita/contribs/lambdadelta/basic_2/syntax/lenv_weight.ma
new file mode 100644 (file)
index 0000000..1a61b7d
--- /dev/null
+++ b/matita/matita/contribs/lambdadelta/basic_2/syntax/lenv_weight.ma
@@ -0,0 +1,34 @@
+(**************************************************************************)
+(*       ___                                                              *)
+(*      ||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 "basic_2/syntax/term_weight.ma".
+include "basic_2/syntax/lenv.ma".
+
+(* WEIGHT OF A LOCAL ENVIRONMENT ********************************************)
+
+rec definition lw L ≝ match L with
+[ LAtom       ⇒ 0
+| LPair L _ V ⇒ lw L + ♯{V}
+].
+
+interpretation "weight (local environment)" 'Weight L = (lw L).
+
+(* Basic properties *********************************************************)
+
+lemma lw_pair: ∀I,L,V. ♯{L} < ♯{L.ⓑ{I}V}.
+/3 width=1 by lt_plus_to_minus_r, monotonic_lt_plus_r/ qed.
+
+(* Basic_1: removed theorems 4: clt_cong clt_head clt_thead clt_wf_ind *)
+(* Basic_1: removed local theorems 1: clt_wf__q_ind *)
+(* Basic_1: note: clt_thead should be renamed clt_ctail *)