-(**************************************************************************)
-(* ___ *)
-(* ||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 *)
-(* *)
-(**************************************************************************)
-
-notation "hvbox( ⦃ L1, break T1 ⦄ > break ⦃ L2 , break T2 ⦄ )"
- non associative with precedence 45
- for @{ 'SupTerm $L1 $T1 $L2 $T2 }.
-
-include "basic_2/substitution/ldrop.ma".
-
-(* SUPCLOSURE ***************************************************************)
-
-inductive csup: bi_relation lenv term ≝
-| csup_lref : ∀I,L,K,V,i. ⇩[0, i] L ≡ K.ⓑ{I}V → csup L (#i) K V
-| csup_bind_sn: ∀a,I,L,V,T. csup L (ⓑ{a,I}V.T) L V
-| csup_bind_dx: ∀a,I,L,V,T. csup L (ⓑ{a,I}V.T) (L.ⓑ{I}V) T
-| csup_flat_sn: ∀I,L,V,T. csup L (ⓕ{I}V.T) L V
-| csup_flat_dx: ∀I,L,V,T. csup L (ⓕ{I}V.T) L T
-.
-
-interpretation
- "structural predecessor (closure)"
- 'SupTerm L1 T1 L2 T2 = (csup L1 T1 L2 T2).
-
-(* Basic inversion lemmas ***************************************************)
-
-fact csup_inv_atom1_aux: ∀L1,L2,T1,T2. ⦃L1, T1⦄ > ⦃L2, T2⦄ → ∀J. T1 = ⓪{J} →
- ∃∃I,i. ⇩[0, i] L1 ≡ L2.ⓑ{I}T2 & J = LRef i.
-#L1 #L2 #T1 #T2 * -L1 -L2 -T1 -T2
-[ #I #L #K #V #i #HLK #J #H destruct /2 width=4/
-| #a #I #L #V #T #J #H destruct
-| #a #I #L #V #T #J #H destruct
-| #I #L #V #T #J #H destruct
-| #I #L #V #T #J #H destruct
-]
-qed-.
-
-lemma csup_inv_atom1: ∀J,L1,L2,T2. ⦃L1, ⓪{J}⦄ > ⦃L2, T2⦄ →
- ∃∃I,i. ⇩[0, i] L1 ≡ L2.ⓑ{I}T2 & J = LRef i.
-/2 width=3 by csup_inv_atom1_aux/ qed-.
-
-fact csup_inv_bind1_aux: ∀L1,L2,T1,T2. ⦃L1, T1⦄ > ⦃L2, T2⦄ →
- ∀b,J,W,U. T1 = ⓑ{b,J}W.U →
- (L2 = L1 ∧ T2 = W) ∨
- (L2 = L1.ⓑ{J}W ∧ T2 = U).
-#L1 #L2 #T1 #T2 * -L1 -L2 -T1 -T2
-[ #I #L #K #V #i #_ #b #J #W #U #H destruct
-| #a #I #L #V #T #b #J #W #U #H destruct /3 width=1/
-| #a #I #L #V #T #b #J #W #U #H destruct /3 width=1/
-| #I #L #V #T #b #J #W #U #H destruct
-| #I #L #V #T #b #J #W #U #H destruct
-]
-qed-.
-
-lemma csup_inv_bind1: ∀b,J,L1,L2,W,U,T2. ⦃L1, ⓑ{b,J}W.U⦄ > ⦃L2, T2⦄ →
- (L2 = L1 ∧ T2 = W) ∨
- (L2 = L1.ⓑ{J}W ∧ T2 = U).
-/2 width=4 by csup_inv_bind1_aux/ qed-.
-
-fact csup_inv_flat1_aux: ∀L1,L2,T1,T2. ⦃L1, T1⦄ > ⦃L2, T2⦄ →
- ∀J,W,U. T1 = ⓕ{J}W.U →
- L2 = L1 ∧ (T2 = W ∨ T2 = U).
-#L1 #L2 #T1 #T2 * -L1 -L2 -T1 -T2
-[ #I #L #K #V #i #_ #J #W #U #H destruct
-| #a #I #L #V #T #J #W #U #H destruct
-| #a #I #L #V #T #J #W #U #H destruct
-| #I #L #V #T #J #W #U #H destruct /3 width=1/
-| #I #L #V #T #J #W #U #H destruct /3 width=1/
-]
-qed-.
-
-lemma csup_inv_flat1: ∀J,L1,L2,W,U,T2. ⦃L1, ⓕ{J}W.U⦄ > ⦃L2, T2⦄ →
- L2 = L1 ∧ (T2 = W ∨ T2 = U).
-/2 width=4 by csup_inv_flat1_aux/ qed-.
-
(* Basic forward lemmas *****************************************************)
-lemma csup_fwd_cw: ∀L1,L2,T1,T2. ⦃L1, T1⦄ > ⦃L2, T2⦄ → #{L2, T2} < #{L1, T1}.
-#L1 #L2 #T1 #T2 * -L1 -L2 -T1 -T2 /width=1/ /2 width=4 by ldrop_pair2_fwd_cw/
-qed-.
-
lemma csup_fwd_ldrop: ∀L1,L2,T1,T2. ⦃L1, T1⦄ > ⦃L2, T2⦄ →
∃i. ⇩[0, i] L1 ≡ L2 ∨ ⇩[0, i] L2 ≡ L1.
#L1 #L2 #T1 #T2 * -L1 -L2 -T1 -T2 /3 width=2/ /4 width=2/
elim (lift_csup_trans_eq … HTU … H) -H -T #T #H
elim (lift_inv_lref2_be … H ? ?) //
qed-.
+
+
+fact csup_inv_all4_refl_aux: ∀L1,L2,T1,T2. ⦃L1, T1⦄ > ⦃L2, T2⦄ → L1 = L2 →
+ ∨∨ ∃∃a,I,U. T1 = ⓑ{a,I}T2.U
+ | ∃∃I,W. T1 = ⓕ{I}W.T2
+ | ∃∃I,U. T1 = ⓕ{I}T2.U.
+#L1 #L2 #T1 #T2 * -L1 -L2 -T1 -T2 /3 width=3/ /3 width=4/
+[ #I #L #K #V #i #HLK #H destruct
+ lapply (ldrop_pair2_fwd_cw … HLK V) -HLK #H
+ elim (lt_refl_false … H)
+| #a #I #L #V #T #H
+ elim (discr_lpair_x_xy … H)
+]
+qed-.
+
+lemma csup_inv_all4_refl: ∀L,T1,T2. ⦃L, T1⦄ > ⦃L, T2⦄ →
+ ∨∨ ∃∃a,I,U. T1 = ⓑ{a,I}T2.U
+ | ∃∃I,W. T1 = ⓕ{I}W.T2
+ | ∃∃I,U. T1 = ⓕ{I}T2.U.
+/2 width=4 by csup_inv_all4_refl_aux/ qed-.
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