(* Advanced properties ******************************************************)
-lemma tc_lfxs_refl: ∀R. (∀L. reflexive … (R L)) → ∀T. reflexive … (tc_lfxs R T).
+lemma tc_lfxs_refl: ∀R. c_reflexive … R →
+ ∀T. reflexive … (tc_lfxs R T).
/3 width=1 by lfxs_refl, inj/ qed.
(* Basic_2A1: uses: TC_lpx_sn_pair TC_lpx_sn_pair_refl *)
-lemma tc_lfxs_pair: ∀R. (∀L. reflexive … (R L)) →
- ∀L,V1,V2. LTC … R L V1 V2 → ∀I,T. L.ⓑ{I}V1 ⦻**[R, T] L.ⓑ{I}V2.
+lemma tc_lfxs_pair_refl: ∀R. c_reflexive … R →
+ ∀L,V1,V2. CTC … R L V1 V2 → ∀I,T. L.ⓑ{I}V1 ⪤**[R, T] L.ⓑ{I}V2.
#R #HR #L #V1 #V2 #H elim H -V2
-/3 width=3 by tc_lfxs_step_dx, lfxs_pair, inj/
+/3 width=3 by tc_lfxs_step_dx, lfxs_pair_refl, inj/
+qed.
+
+lemma tc_lfxs_tc: ∀R,L1,L2,T,f. 𝐈⦃f⦄ → TC … (lexs cfull (cext2 R) f) L1 L2 →
+ L1 ⪤**[R, T] L2.
+#R #L1 #L2 #T #f #Hf #H elim H -L2
+[ elim (frees_total L1 T) | #L elim (frees_total L T) ]
+/5 width=7 by lexs_sdj, tc_lfxs_step_dx, sdj_isid_sn, inj, ex2_intro/
qed.
(* Advanced eliminators *****************************************************)
-lemma tc_lfxs_ind_sn: ∀R. (∀L. reflexive … (R L)) →
- ∀L1,T. ∀R0:predicate …. R0 L1 →
- (â\88\80L,L2. L1 ⦻**[R, T] L â\86\92 L ⦻*[R, T] L2 â\86\92 R0 L â\86\92 R0 L2) →
- â\88\80L2. L1 ⦻**[R, T] L2 â\86\92 R0 L2.
-#R #HR #L1 #T #R0 #HL1 #IHL1 #L2 #HL12
+lemma tc_lfxs_ind_sn: ∀R. c_reflexive … R →
+ ∀L1,T. ∀Q:predicate …. Q L1 →
+ (â\88\80L,L2. L1 ⪤**[R, T] L â\86\92 L ⪤*[R, T] L2 â\86\92 Q L â\86\92 Q L2) →
+ â\88\80L2. L1 ⪤**[R, T] L2 â\86\92 Q L2.
+#R #HR #L1 #T #Q #HL1 #IHL1 #L2 #HL12
@(TC_star_ind … HL1 IHL1 … HL12) /2 width=1 by lfxs_refl/
qed-.
-lemma tc_lfxs_ind_dx: ∀R. (∀L. reflexive … (R L)) →
- ∀L2,T. ∀R0:predicate …. R0 L2 →
- (â\88\80L1,L. L1 ⦻*[R, T] L â\86\92 L ⦻**[R, T] L2 â\86\92 R0 L â\86\92 R0 L1) →
- â\88\80L1. L1 ⦻**[R, T] L2 â\86\92 R0 L1.
-#R #HR #L2 #R0 #HL2 #IHL2 #L1 #HL12
+lemma tc_lfxs_ind_dx: ∀R. c_reflexive … R →
+ ∀L2,T. ∀Q:predicate …. Q L2 →
+ (â\88\80L1,L. L1 ⪤*[R, T] L â\86\92 L ⪤**[R, T] L2 â\86\92 Q L â\86\92 Q L1) →
+ â\88\80L1. L1 ⪤**[R, T] L2 â\86\92 Q L1.
+#R #HR #L2 #Q #HL2 #IHL2 #L1 #HL12
@(TC_star_ind_dx … HL2 IHL2 … HL12) /2 width=4 by lfxs_refl/
qed-.
+
+(* Advanced inversion lemmas ************************************************)
+
+lemma tc_lfxs_inv_bind_void: ∀R. c_reflexive … R →
+ ∀p,I,L1,L2,V,T. L1 ⪤**[R, ⓑ{p,I}V.T] L2 →
+ L1 ⪤**[R, V] L2 ∧ L1.ⓧ ⪤**[R, T] L2.ⓧ.
+#R #HR #p #I #L1 #L2 #V #T #H @(tc_lfxs_ind_sn … HR … H) -L2
+[ /3 width=1 by tc_lfxs_refl, conj/
+| #L #L2 #_ #H * elim (lfxs_inv_bind_void … H) -H /3 width=3 by tc_lfxs_step_dx, conj/
+]
+qed-.
+
+(* Advanced forward lemmas **************************************************)
+
+lemma tc_lfxs_fwd_bind_dx_void: ∀R. c_reflexive … R →
+ ∀p,I,L1,L2,V,T. L1 ⪤**[R, ⓑ{p,I}V.T] L2 →
+ L1.ⓧ ⪤**[R, T] L2.ⓧ.
+#R #HR #p #I #L1 #L2 #V #T #H elim (tc_lfxs_inv_bind_void … H) -H //
+qed-.