+++ /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/grammar/lenv_append.ma".
-include "basic_2/substitution/drop.ma".
-
-(* DROPPING *****************************************************************)
-
-(* Properties on append for local environments ******************************)
-
-fact drop_O1_append_sn_le_aux: ∀L1,L2,s,l,m. ⬇[s, l, m] L1 ≡ L2 →
- l = 0 → m ≤ |L1| →
- ∀L. ⬇[s, 0, m] L @@ L1 ≡ L @@ L2.
-#L1 #L2 #s #l #m #H elim H -L1 -L2 -l -m //
-[ #l #m #_ #_ #H >(yle_inv_O2 … H) -m //
-| /4 width=1 by drop_drop, yle_inv_succ/
-| #I #L1 #L2 #V1 #V2 #l #m #_ #_ #_ #H elim (ysucc_inv_O_dx … H)
-]
-qed-.
-
-lemma drop_O1_append_sn_le: ∀L1,L2,s,m. ⬇[s, yinj 0, m] L1 ≡ L2 → m ≤ |L1| →
- ∀L. ⬇[s, 0, m] L @@ L1 ≡ L @@ L2.
-/2 width=3 by drop_O1_append_sn_le_aux/ qed.
-
-(* Inversion lemmas on append for local environments ************************)
-
-lemma drop_O1_inv_append1_ge: ∀K,L1,L2,s,m. ⬇[s, 0, m] L1 @@ L2 ≡ K →
- ∀m0. |L2| + m0 = m → ⬇[s, 0, m0] L1 ≡ K.
-#K #L1 #L2 elim L2 -L2
-[ #s #m #H #m0 >yplus_O1 #H0 destruct //
-| #L2 #I #V #IHL2 #s #m #H #m0 >yplus_succ1
- #H0 elim (drop_inv_O1_pair1 … H) -H * #Hm #HL12 destruct
- [ elim (ysucc_inv_O_dx … Hm)
- | /2 width=3 by/
- ]
-]
-qed-.
-
-lemma drop_O1_inv_append1_le: ∀K,L1,L2,s,m. ⬇[s, 0, m] L1 @@ L2 ≡ K → m ≤ |L2| →
- ∀K2. ⬇[s, 0, m] L2 ≡ K2 → K = L1 @@ K2.
-#K #L1 #L2 elim L2 -L2
-[ #s #m #H1 #H2 #K2 #H3 lapply (yle_inv_O2 … H2) -H2
- #H2 elim (drop_inv_atom1 … H3) -H3 #H3 #_ destruct
- >(drop_inv_O2 … H1) -H1 //
-| #L2 #I #V #IHL2 #s #m @(ynat_ind … m) -m [ -IHL2 || -IHL2 ]
- [ #H1 #_ #K2 #H2
- lapply (drop_inv_O2 … H1) -H1 #H1
- lapply (drop_inv_O2 … H2) -H2 #H2 destruct //
- | /3 width=7 by drop_inv_drop1, yle_inv_succ/
- | #_ #H lapply (yle_inv_Y1 … H) -H
- #H elim (ylt_yle_false (|L2.ⓑ{I}V|) (∞)) //
- ]
-]
-qed-.