matita/matita/contribs/lambdadelta/basic_2/computation/yprs_lift.ma

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   3 (*      ||M||                                                             *)
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  14
  15 include "basic_2/unfold/lsstas_lift.ma".
  16 include "basic_2/computation/yprs.ma".
  17
  18 (* "BIG TREE" PARALLEL COMPUTATION FOR CLOSURES *****************************)
  19
  20 (* Advanced properties ******************************************************)
  21
  22 lemma lsstas_yprs: ∀h,g,G,L,T1,T2,l2. ⦃G, L⦄ ⊢ T1 •*[h, g, l2] T2 →
  23                    ∀l1. l2 ≤ l1 → ⦃G, L⦄ ⊢ T1 ▪[h, g] l1 → ⦃G, L, T1⦄ ≥[h, g] ⦃G, L, T2⦄.
  24 #h #g #G #L #T1 #T2 #l2 #H @(lsstas_ind_dx … H) -l2 -T2 //
  25 #l2 #T #T2 #HT1 #HT2 #IHT1 #l1 >commutative_plus #Hl21 #Hl1
  26 elim (le_inv_plus_l … Hl21) -Hl21 #Hl12 #Hl21
  27 lapply (lsstas_da_conf … HT1 … Hl1) -HT1
  28 >(plus_minus_m_m … Hl12) -Hl12
  29 /3 width=5 by ypr_ssta, yprs_strap1/
  30 qed.