matita/matita/contribs/lambdadelta/basic_2A/etc/fsup/ldrop_fsups.etc

   1 (**************************************************************************)
   2 (*       ___                                                              *)
   3 (*      ||M||                                                             *)
   4 (*      ||A||       A project by Andrea Asperti                           *)
   5 (*      ||T||                                                             *)
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   9 (*      \   /                                                             *)
  10 (*       \ /        This file is distributed under the terms of the       *)
  11 (*        v         GNU General Public License Version 2                  *)
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  13 (**************************************************************************)
  14
  15 include "basic_2/grammar/fsups.ma".
  16 include "basic_2/substitution/ldrop_fsup.ma".
  17
  18 (* LOCAL ENVIRONMENT SLICING ************************************************)
  19
  20 (* Inversion lemmas on plus-iterated supclosure  ****************************)
  21
  22 lemma fsupp_inv_atom1_fsups: ∀J,L1,L2,T2. ⦃L1, ⓪{J}⦄ ⊃+ ⦃L2, T2⦄ →
  23                              ∃∃I,K,V,i. ⇩[0, i] L1 ≡ K.ⓑ{I}V &
  24                              ⦃K, V⦄ ⊃* ⦃L2, T2⦄ & J = LRef i.
  25 #J #L1 #L2 #T2 #H @(fsupp_ind … H) -L2 -T2
  26 [ #L2 #T2 #H
  27   elim (fsup_inv_atom1_ldrop … H) -H * #i #HL12 #H destruct /2 width=7/
  28 | #L #T #L2 #T2 #_ #HT2 * #I #K #V #i #HLK #HVT #H destruct /3 width=8/
  29 ]
  30 qed-.