+++ /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/notation/functions/voidstar_2.ma".
-include "basic_2/syntax/lenv.ma".
-
-(* EXTENSION OF A LOCAL ENVIRONMENT WITH EXCLUSION BINDERS ******************)
-
-rec definition voids (L:lenv) (n:nat) on n: lenv ≝ match n with
-[ O ⇒ L | S m ⇒ (voids L m).ⓧ ].
-
-interpretation "extension with exclusion binders (local environment)"
- 'VoidStar n L = (voids L n).
-
-(* Basic properties *********************************************************)
-
-lemma voids_zero: ∀L. L = ⓧ*[0]L.
-// qed.
-
-lemma voids_succ: ∀L,n. (ⓧ*[n]L).ⓧ = ⓧ*[⫯n]L.
-// qed.
-
-(* Advanced properties ******************************************************)
-
-lemma voids_next: ∀n,L. ⓧ*[n](L.ⓧ) = ⓧ*[⫯n]L.
-#n elim n -n //
-qed.
-
-(* Basic inversion lemmas ***************************************************)
-
-lemma voids_atom_inv: ∀K,n. ⓧ*[n]K = ⋆ → ∧∧ ⋆ = K & 0 = n.
-#K * /2 width=1 by conj/
-#n <voids_succ #H destruct
-qed-.
-
-lemma voids_pair_inv: ∀I,K1,K2,V,n. ⓧ*[n]K1 = K2.ⓑ{I}V →
- ∧∧ K2.ⓑ{I}V = K1 & 0 = n.
-#I #K1 #K2 #V * /2 width=1 by conj/
-#n <voids_succ #H destruct
-qed-.
-
-(* Advanced inversion lemmas ************************************************)
-
-lemma voids_inv_atom_sn: ∀n1,K2,n2. ⓧ*[n1]⋆ = ⓧ*[n2]K2 →
- ∧∧ ⓧ*[n1-n2]⋆ = K2 & n2 ≤ n1.
-#n1 elim n1 -n1
-[ #K2 <voids_zero * /2 width=1 by conj/
- #n1 <voids_succ #H destruct
-| #n1 #IH #K2 *
- [ <voids_zero #H destruct /2 width=1 by conj/
- | #n2 <voids_succ <voids_succ >minus_S_S #H
- elim (destruct_lbind_lbind_aux … H) -H #HK #_ (**) (* destruct lemma needed *)
- elim (IH … HK) -IH -HK #H #Hn destruct /3 width=1 by conj, le_S_S/
- ]
-]
-qed-.
-
-lemma voids_inv_pair_sn: ∀I,V,n1,K1,K2,n2. ⓧ*[n1]K1.ⓑ{I}V = ⓧ*[n2]K2 →
- ∧∧ ⓧ*[n1-n2]K1.ⓑ{I}V = K2 & n2 ≤ n1.
-#I #V #n1 elim n1 -n1
-[ #K1 #K2 <voids_zero * /2 width=1 by conj/
- #n1 <voids_succ #H destruct
-| #n1 #IH #K1 #K2 *
- [ <voids_zero #H destruct /2 width=1 by conj/
- | #n2 <voids_succ <voids_succ >minus_S_S #H
- elim (destruct_lbind_lbind_aux … H) -H #HK #_ (**) (* destruct lemma needed *)
- elim (IH … HK) -IH -HK #H #Hn destruct /3 width=1 by conj, le_S_S/
- ]
-]
-qed-.
-
-(* Main inversion properties ************************************************)
-
-theorem voids_inj: ∀n. injective … (λL. ⓧ*[n]L).
-#n elim n -n //
-#n #IH #L1 #L2
-<voids_succ <voids_succ #H
-elim (destruct_lbind_lbind_aux … H) -H (**) (* destruct lemma needed *)
-/2 width=1 by/
-qed-.