(* Main inversion lemmas ****************************************************)
-theorem aaa_mono: â\88\80G,L,T,A1. â¦\83G,Lâ¦\84 â\8a¢ T â\81\9d A1 â\86\92 â\88\80A2. â¦\83G,Lâ¦\84 ⊢ T ⁝ A2 → A1 = A2.
+theorem aaa_mono: â\88\80G,L,T,A1. â\9dªG,Lâ\9d« â\8a¢ T â\81\9d A1 â\86\92 â\88\80A2. â\9dªG,Lâ\9d« ⊢ T ⁝ A2 → A1 = A2.
#G #L #T #A1 #H elim H -G -L -T -A1
[ #G #L #s #A2 #H >(aaa_inv_sort … H) -H //
| #I1 #G #L #V1 #B #_ #IH #A2 #H
elim (aaa_inv_cast … H) -H /2 width=1 by/
]
qed-.
+
+(* Advanced inversion lemmas ************************************************)
+
+lemma aaa_aaa_inv_appl (G) (L) (V) (T) (B) (X):
+ ∀A. ❪G,L❫ ⊢ ⓐV.T ⁝ A → ❪G,L❫ ⊢ V ⁝ B → ❪G,L❫⊢ T ⁝ X → ②B.A = X.
+#G #L #V #T #B #X #A #H #H1V #H1T
+elim (aaa_inv_appl … H) -H #B0 #H2V #H2T
+lapply (aaa_mono … H2V … H1V) -V #H destruct
+lapply (aaa_mono … H2T … H1T) -G -L -T //
+qed-.
+
+lemma aaa_aaa_inv_cast (G) (L) (U) (T) (B) (A):
+ ∀X. ❪G,L❫ ⊢ ⓝU.T ⁝ X → ❪G,L❫ ⊢ U ⁝ B → ❪G,L❫⊢ T ⁝ A → ∧∧ B = X & A = X.
+#G #L #U #T #B #A #X #H #H1U #H1T
+elim (aaa_inv_cast … H) -H #H2U #H2T
+lapply (aaa_mono … H1U … H2U) -U #HB
+lapply (aaa_mono … H1T … H2T) -G -L -T #HA
+/2 width=1 by conj/
+qed-.