matita/matita/contribs/lambda_delta/basic_2/reducibility/cnf.ma

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  14
  15 include "basic_2/reducibility/cpr.ma".
  16
  17 (* CONTEXT-SENSITIVE NORMAL TERMS *******************************************)
  18
  19 definition cnf: lenv → predicate term ≝ λL. NF … (cpr L) (eq …).
  20
  21 interpretation
  22    "context-sensitive normality (term)"
  23    'Normal L T = (cnf L T).
  24
  25 (* Basic properties *********************************************************)
  26
  27 (* Basic_1: was: nf2_sort *)
  28 lemma cnf_sort: ∀L,k. L ⊢ 𝐍[⋆k].
  29 #L #k #X #H
  30 >(cpr_inv_sort1 … H) //
  31 qed.
  32
  33 axiom cnf_dec: ∀L,T1. L ⊢ 𝐍[T1] ∨
  34                ∃∃T2. L ⊢ T1 ➡ T2 & (T1 = T2 → False).
  35
  36 (* Basic_1: removed theorems 1: nf2_abst_shift *)