X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambda_delta%2Fbasic_2%2Funfold%2Fthin.ma;h=65fb76fe0dc7fe77bc8f4bf930d45fdee2f44d01;hb=5613a25cee29ef32a597cb4b44e8f2f4d71c4df0;hp=0b4da98f9532e57c16a84e7125c70cbe22df7d0f;hpb=913512bbc9202f2109d53acd43dc8c0270b17184;p=helm.git

diff --git a/matita/matita/contribs/lambda_delta/basic_2/unfold/thin.ma b/matita/matita/contribs/lambda_delta/basic_2/unfold/thin.ma
index 0b4da98f9..65fb76fe0 100644
--- a/matita/matita/contribs/lambda_delta/basic_2/unfold/thin.ma
+++ b/matita/matita/contribs/lambda_delta/basic_2/unfold/thin.ma
@@ -12,14 +12,26 @@
 (*                                                                        *)
 (**************************************************************************)
 
-include "basic_2/unfold/ltpss.ma".
+include "basic_2/unfold/ltpss_sn.ma".
 
-(* DELIFT ON LOCAL ENVIRONMENTS  ********************************************)
+(* BASIC LOCAL ENVIRONMENT THINNING *****************************************)
 
 definition thin: nat → nat → relation lenv ≝
-                 λd,e,L1,L2. ∃∃L. L1 [d, e] ▶* L & ⇩[d, e] L ≡ L2.
+                 λd,e,L1,L2. ∃∃L. L1 ⊢ ▶* [d, e] L & ⇩[d, e] L ≡ L2.
 
-interpretation "delift (local environment)"
+interpretation "basic thinning (local environment)"
    'TSubst L1 d e L2 = (thin d e L1 L2).
 
 (* Basic properties *********************************************************)
+
+lemma ldrop_thin: ∀L1,L2,d,e. ⇩[d, e] L1 ≡ L2 → ▼*[d, e] L1 ≡ L2.
+/2 width=3/ qed.
+
+(* Basic inversion lemmas ***************************************************)
+
+lemma thin_inv_thin1: ∀I,K1,V1,L2,e. ▼*[0, e] K1.ⓑ{I} V1 ≡ L2 → 0 < e →
+                      ▼*[0, e - 1] K1 ≡ L2.
+#I #K1 #V1 #L2 #e * #X #HK1 #HL2 #e
+elim (ltpss_sn_inv_tpss21 … HK1 ?) -HK1 // #K #V #HK1 #_ #H destruct
+lapply (ldrop_inv_ldrop1 … HL2 ?) -HL2 // /2 width=3/
+qed-.