+++ /dev/null
-(**************************************************************************)
-(* ___ *)
-(* ||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 *)
-(* *)
-(**************************************************************************)
-
-include "Basic_2/unfold/delift_lift.ma".
-include "Basic_2/functional/lift.ma".
-
-(* CORE SUBSTITUTION ********************************************************)
-
-let rec fsubst W d U on U ≝ match U with
-[ TAtom I ⇒ match I with
- [ Sort _ ⇒ U
- | LRef i ⇒ tri … i d (#i) (↑[0, i] W) (#(i-1))
- | GRef _ ⇒ U
- ]
-| TPair I V T ⇒ match I with
- [ Bind2 I ⇒ ⓑ{I} (fsubst W d V). (fsubst W (d+1) T)
- | Flat2 I ⇒ ⓕ{I} (fsubst W d V). (fsubst W d T)
- ]
-].
-
-interpretation "functional core substitution" 'Subst V d T = (fsubst V d T).
-
-(* Main properties **********************************************************)
-
-theorem fsubst_delift: ∀K,V,T,L,d.
- ⇩[0, d] L ≡ K. ⓓV → L ⊢ T [d, 1] ≡ [d ← V] T.
-#K #V #T elim T -T
-[ * #i #L #d #HLK normalize in ⊢ (? ? ? ? ? %); /2 width=3/
- elim (lt_or_eq_or_gt i d) #Hid
- [ -HLK >(tri_lt ?????? Hid) /3 width=3/
- | destruct >tri_eq /4 width=4 by tpss_strap, tps_subst, le_n, ex2_1_intro/ (**) (* too slow without trace *)
- | -HLK >(tri_gt ?????? Hid) /3 width=3/
- ]
-| * /3 width=1/ /4 width=1/
-]
-qed.
-
-(* Main inversion properties ************************************************)
-
-theorem fsubst_inv_delift: ∀K,V,T1,L,T2,d. ⇩[0, d] L ≡ K. ⓓV →
- L ⊢ T1 [d, 1] ≡ T2 → [d ← V] T1 = T2.
-#K #V #T1 elim T1 -T1
-[ * #i #L #T2 #d #HLK #H
- [ -HLK >(delift_fwd_sort1 … H) -H //
- | elim (lt_or_eq_or_gt i d) #Hid normalize
- [ -HLK >(delift_fwd_lref1_lt … H) -H // /2 width=1/
- | destruct
- elim (delift_fwd_lref1_be … H ? ?) -H // #K0 #V0 #V2 #HLK0
- lapply (ldrop_mono … HLK0 … HLK) -HLK0 -HLK #H >minus_plus <minus_n_n #HV2 #HVT2 destruct
- >(delift_inv_refl_O2 … HV2) -V >(flift_inv_lift … HVT2) -V2 //
- | -HLK >(delift_fwd_lref1_ge … H) -H // /2 width=1/
- ]
- | -HLK >(delift_fwd_gref1 … H) -H //
- ]
-| * #I #V1 #T1 #IHV1 #IHT1 #L #X #d #HLK #H
- [ elim (delift_fwd_bind1 … H) -H #V2 #T2 #HV12 #HT12 #H destruct
- <(IHV1 … HV12) -IHV1 -HV12 // <(IHT1 … HT12) -IHT1 -HT12 // /2 width=1/
- | elim (delift_fwd_flat1 … H) -H #V2 #T2 #HV12 #HT12 #H destruct
- <(IHV1 … HV12) -IHV1 -HV12 // <(IHT1 … HT12) -IHT1 -HT12 //
- ]
-]
-qed-.