matita/matita/contribs/lambda_delta/basic_2/equivalence/cpcs_ltpss.ma

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  14
  15 include "basic_2/equivalence/cpcs_cpcs.ma".
  16
  17 (* CONTEXT-SENSITIVE PARALLEL EQUIVALENCE ON TERMS **************************)
  18
  19 (* Properties concerning partial unfold on local environments ***************)
  20
  21 lemma ltpss_dx_cpr_conf: ∀L1,L2,d,e. L1 ▶* [d, e] L2 →
  22                          ∀T1,T2. L1 ⊢ T1 ➡ T2 → L2 ⊢ T1 ⬌* T2.
  23 #L1 #L2 #d #e #HL12 #T1 #T2 *
  24 lapply (ltpss_dx_weak_all … HL12)
  25 >(ltpss_dx_fwd_length … HL12) -HL12 #HL12 #T #HT1 #HT2
  26 elim (ltpss_dx_tpss_conf … HT2 … HL12) -L1 #T0 #HT0 #HT20
  27 @(cprs_div … T0) /3 width=3/ (**) (* /4/ is too slow *)
  28 qed.
  29
  30 lemma ltpss_dx_cprs_conf: ∀L1,L2,d,e. L1 ▶* [d, e] L2 →
  31                           ∀T1,T2. L1 ⊢ T1 ➡* T2 → L2 ⊢ T1 ⬌* T2.
  32 #L1 #L2 #d #e #HL12 #T1 #T2 #H @(cprs_ind … H) -T2 //
  33 #T #T2 #_ #HT2 #IHT1
  34 @(cpcs_trans … IHT1) -T1 /2 width=5/
  35 qed.
  36
  37 lemma ltpss_dx_cpcs_conf: ∀L1,L2,d,e. L1 ▶* [d, e] L2 →
  38                           ∀T1,T2. L1 ⊢ T1 ⬌* T2 → L2 ⊢ T1 ⬌* T2.
  39 #L1 #L2 #d #e #HL12 #T1 #T2 #H
  40 elim (cpcs_inv_cprs … H) -H #T #HT1 #HT2
  41 @(cpcs_canc_dx … T) /2 width=5/
  42 qed.