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4 (* ||A|| A project by Andrea Asperti *)
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15 include "static_2/static/rex_length.ma".
16 include "static_2/i_static/rexs.ma".
18 (* ITERATED EXTENSION ON REFERRED ENTRIES OF A CONTEXT-SENSITIVE REALTION ***)
20 (* Forward lemmas with length for local environments ************************)
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 //