matita/matita/contribs/lambdadelta/basic_2/i_static/rexs_length.ma

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   3 (*      ||M||                                                             *)
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  14
  15 include "basic_2/static/rex_length.ma".
  16 include "basic_2/i_static/rexs.ma".
  17
  18 (* ITERATED EXTENSION ON REFERRED ENTRIES OF A CONTEXT-SENSITIVE REALTION ***)
  19
  20 (* Forward lemmas with length for local environments ************************)
  21
  22 (* Basic_2A1: uses: TC_lpx_sn_fwd_length *)
  23 lemma rexs_fwd_length: ∀R,L1,L2,T. L1 ⪤*[R, T] L2 → |L1| = |L2|.
  24 #R #L1 #L2 #T #H elim H -L2
  25 [ #L2 #HL12 >(rex_fwd_length … HL12) -HL12 //
  26 | #L #L2 #_ #HL2 #IHL1
  27   >IHL1 -L1 >(rex_fwd_length … HL2) -HL2 //
  28 ]
  29 qed-.