matita/matita/contribs/lambdadelta/ground_2/etc/relocation/trace_sor.etc

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  14
  15 include "ground_2/notation/relations/runion_3.ma".
  16 include "ground_2/relocation/trace_isid.ma".
  17
  18 (* RELOCATION TRACE *********************************************************)
  19
  20 inductive sor: relation3 trace trace trace ≝
  21    | sor_empty: sor (◊) (◊) (◊)
  22    | sor_inh  : ∀cs1,cs2,cs. sor cs1 cs2 cs →
  23                 ∀b1,b2. sor (b1 @ cs1) (b2 @ cs2) ((b1 ∨ b2) @ cs).
  24
  25 interpretation
  26    "union (trace)"
  27    'RUnion L1 L2 L = (sor L2 L1 L).
  28
  29 (* Basic properties *********************************************************)
  30
  31 lemma sor_length: ∀cs1,cs2. |cs1| = |cs2| →
  32                   ∃∃cs. cs2 ⋓ cs1 ≡ cs & |cs| = |cs1| & |cs| = |cs2|.
  33 #cs1 elim cs1 -cs1
  34 [ #cs2 #H >(length_inv_zero_sn … H) -H /2 width=4 by sor_empty, ex3_intro/
  35 | #b1 #cs1 #IH #x #H elim (length_inv_succ_sn … H) -H
  36   #cs2 #b2 #H12 #H destruct elim (IH … H12) -IH -H12
  37   #cs #H12 #H1 #H2 @(ex3_intro … ((b1 ∨ b2) @ cs)) /2 width=1 by sor_inh/ (**) (* explicit constructor *)
  38 ]
  39 qed-.
  40
  41 lemma sor_sym: ∀cs1,cs2,cs. cs1 ⋓ cs2 ≡ cs → cs2 ⋓ cs1 ≡ cs.
  42 #cs1 #cs2 #cs #H elim H -cs1 -cs2 -cs /2 width=1 by sor_inh/
  43 qed-.
  44
  45 (* Basic inversion lemmas ***************************************************)
  46
  47 lemma sor_inv_length: ∀cs1,cs2,cs. cs2 ⋓ cs1 ≡ cs →
  48                       ∧∧ |cs1| = |cs2| & |cs| = |cs1| & |cs| = |cs2|.
  49 #cs1 #cs2 #cs #H elim H -cs1 -cs2 -cs /2 width=1 by and3_intro/
  50 #cs1 #cs2 #cs #_ #b1 #b2 * /2 width=1 by and3_intro/
  51 qed-.
  52
  53 (* Basic forward lemmas *****************************************************)
  54
  55 lemma sor_fwd_isid_sn: ∀cs1,cs2,cs. cs1 ⋓ cs2 ≡ cs → 𝐈⦃cs1⦄ → 𝐈⦃cs⦄.
  56 #cs1 #cs2 #cs #H elim H -cs1 -cs2 -cs //
  57 #cs1 #cs2 #cs #_ #b1 #b2 #IH #H elim (isid_inv_cons … H) -H
  58 /3 width=1 by isid_true/
  59 qed-.
  60
  61 lemma sor_fwd_isid_dx: ∀cs1,cs2,cs. cs1 ⋓ cs2 ≡ cs → 𝐈⦃cs2⦄ → 𝐈⦃cs⦄.
  62 /3 width=4 by sor_fwd_isid_sn, sor_sym/ qed-.