X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fbasic_2%2Fstatic%2Flfeq.ma;h=f7375afbc829971da4837150469b46705fab7f0d;hb=5c186c72f508da0849058afeecc6877cd9ed6303;hp=cc3fce365629f263bcccd1faa243aa485a0628a0;hpb=e6282b0c066eee7329560e1929150776ca64aa4a;p=helm.git

diff --git a/matita/matita/contribs/lambdadelta/basic_2/static/lfeq.ma b/matita/matita/contribs/lambdadelta/basic_2/static/lfeq.ma
index cc3fce365..f7375afbc 100644
--- a/matita/matita/contribs/lambdadelta/basic_2/static/lfeq.ma
+++ b/matita/matita/contribs/lambdadelta/basic_2/static/lfeq.ma
@@ -12,7 +12,7 @@
 (*                                                                        *)
 (**************************************************************************)
 
-include "basic_2/notation/relations/lazyeqsn_3.ma".
+include "basic_2/notation/relations/ideqsn_3.ma".
 include "basic_2/static/lfxs.ma".
 
 (* SYNTACTIC EQUIVALENCE FOR LOCAL ENVIRONMENTS ON REFERRED ENTRIES *********)
@@ -23,12 +23,82 @@ definition lfeq: relation3 term lenv lenv ≝
 
 interpretation
    "syntactic equivalence on referred entries (local environment)"
-   'LazyEqSn T L1 L2 = (lfeq T L1 L2).
+   'IdEqSn T L1 L2 = (lfeq T L1 L2).
 
-(***************************************************)
+(* Note: "lfeq_transitive R" is equivalent to "lfxs_transitive ceq R R" *)
+(* Basic_2A1: uses: lleq_transitive *)
+definition lfeq_transitive: predicate (relation3 lenv term term) ≝
+           λR. ∀L2,T1,T2. R L2 T1 T2 → ∀L1. L1 ≡[T1] L2 → R L1 T1 T2.
 
-axiom lfeq_lfxs_trans: ∀R,L1,L,T. L1 ≡[T] L →
-                       ∀L2. L ⪤*[R, T] L2 → L1 ⪤*[R, T] L2.
+(* Basic inversion lemmas ***************************************************)
+
+lemma lfeq_inv_bind: ∀p,I,L1,L2,V,T. L1 ≡[ⓑ{p,I}V.T] L2 →
+                     ∧∧ L1 ≡[V] L2 & L1.ⓑ{I}V ≡[T] L2.ⓑ{I}V.
+/2 width=2 by lfxs_inv_bind/ qed-.
+
+lemma lfeq_inv_flat: ∀I,L1,L2,V,T. L1 ≡[ⓕ{I}V.T] L2 →
+                     ∧∧ L1 ≡[V] L2 & L1 ≡[T] L2.
+/2 width=2 by lfxs_inv_flat/ qed-.
+
+(* Advanced inversion lemmas ************************************************)
+
+lemma lfeq_inv_zero_pair_sn: ∀I,L2,K1,V. K1.ⓑ{I}V ≡[#0] L2 →
+                             ∃∃K2. K1 ≡[V] K2 & L2 = K2.ⓑ{I}V.
+#I #L2 #K1 #V #H
+elim (lfxs_inv_zero_pair_sn … H) -H #K2 #X #HK12 #HX #H destruct
+/2 width=3 by ex2_intro/
+qed-.
+
+lemma lfeq_inv_zero_pair_dx: ∀I,L1,K2,V. L1 ≡[#0] K2.ⓑ{I}V →
+                             ∃∃K1. K1 ≡[V] K2 & L1 = K1.ⓑ{I}V.
+#I #L1 #K2 #V #H
+elim (lfxs_inv_zero_pair_dx … H) -H #K1 #X #HK12 #HX #H destruct
+/2 width=3 by ex2_intro/
+qed-.
+
+lemma lfeq_inv_lref_bind_sn: ∀I1,K1,L2,i. K1.ⓘ{I1} ≡[#↑i] L2 →
+                             ∃∃I2,K2. K1 ≡[#i] K2 & L2 = K2.ⓘ{I2}.
+/2 width=2 by lfxs_inv_lref_bind_sn/ qed-.
+
+lemma lfeq_inv_lref_bind_dx: ∀I2,K2,L1,i. L1 ≡[#↑i] K2.ⓘ{I2} →
+                             ∃∃I1,K1. K1 ≡[#i] K2 & L1 = K1.ⓘ{I1}.
+/2 width=2 by lfxs_inv_lref_bind_dx/ qed-.
+
+(* Basic forward lemmas *****************************************************)
+
+(* Basic_2A1: was: llpx_sn_lrefl *)
+(* Note: this should have been lleq_fwd_llpx_sn *)
+lemma lfeq_fwd_lfxs: ∀R. c_reflexive … R →
+                     ∀L1,L2,T. L1 ≡[T] L2 → L1 ⪤*[R, T] L2.
+#R #HR #L1 #L2 #T * #f #Hf #HL12
+/4 width=7 by lexs_co, cext2_co, ex2_intro/
+qed-.
+
+(* Basic_properties *********************************************************)
+
+lemma frees_lfeq_conf: ∀f,L1,T. L1 ⊢ 𝐅*⦃T⦄ ≘ f →
+                       ∀L2. L1 ≡[T] L2 → L2 ⊢ 𝐅*⦃T⦄ ≘ f.
+#f #L1 #T #H elim H -f -L1 -T
+[ /2 width=3 by frees_sort/
+| #f #i #Hf #L2 #H2
+  >(lfxs_inv_atom_sn … H2) -L2
+  /2 width=1 by frees_atom/
+| #f #I #L1 #V1 #_ #IH #Y #H2
+  elim (lfeq_inv_zero_pair_sn … H2) -H2 #L2 #HL12 #H destruct
+  /3 width=1 by frees_pair/
+| #f #I #L1 #Hf #Y #H2
+  elim (lfxs_inv_zero_unit_sn … H2) -H2 #g #L2 #_ #_ #H destruct
+  /2 width=1 by frees_unit/
+| #f #I #L1 #i #_ #IH #Y #H2
+  elim (lfeq_inv_lref_bind_sn … H2) -H2 #J #L2 #HL12 #H destruct
+  /3 width=1 by frees_lref/
+| /2 width=1 by frees_gref/
+| #f1V #f1T #f1 #p #I #L1 #V1 #T1 #_ #_ #Hf1 #IHV #IHT #L2 #H2
+  elim (lfeq_inv_bind … H2) -H2 /3 width=5 by frees_bind/
+| #f1V #f1T #f1 #I #L1 #V1 #T1 #_ #_ #Hf1 #IHV #IHT #L2 #H2
+  elim (lfeq_inv_flat … H2) -H2 /3 width=5 by frees_flat/
+]
+qed-.
 
 (* Basic_2A1: removed theorems 10:
               lleq_ind lleq_fwd_lref