(* Basic inversion lemmas ***************************************************)
-axiom lifts_inv_applv1: ∀V1s,U1,T2,des. ⇧*[des] Ⓐ V1s. U1 ≡ T2 →
+lemma lifts_inv_applv1: ∀V1s,U1,T2,des. ⇧*[des] Ⓐ V1s. U1 ≡ T2 →
∃∃V2s,U2. ⇧*[des] V1s ≡ V2s & ⇧*[des] U1 ≡ U2 &
T2 = Ⓐ V2s. U2.
+#V1s elim V1s -V1s normalize
+[ #T1 #T2 #des #HT12
+ @(ex3_2_intro) [3,4: // |1,2: skip | // ] (**) (* explicit constructor *)
+| #V1 #V1s #IHV1s #T1 #X #des #H
+ elim (lifts_inv_flat1 … H) -H #V2 #Y #HV12 #HY #H destruct
+ elim (IHV1s … HY) -IHV1s -HY #V2s #T2 #HV12s #HT12 #H destruct
+ @(ex3_2_intro) [4: // |3: /2 width=2/ |1,2: skip | // ] (**) (* explicit constructor *)
+]
+qed-.
(* Basic properties *********************************************************)
-lemma liftsv_applv: ∀V1s,V2s,des. ⇧*[des] V1s ≡ V2s →
- ∀T1,T2. ⇧*[des] T1 ≡ T2 →
- ⇧*[des] Ⓐ V1s. T1 ≡ Ⓐ V2s. T2.
+lemma lifts_applv: ∀V1s,V2s,des. ⇧*[des] V1s ≡ V2s →
+ ∀T1,T2. ⇧*[des] T1 ≡ T2 →
+ ⇧*[des] Ⓐ V1s. T1 ≡ Ⓐ V2s. T2.
#V1s #V2s #des #H elim H -V1s -V2s // /3 width=1/
qed.