+++ /dev/null
-(**************************************************************************)
-(* ___ *)
-(* ||M|| *)
-(* ||A|| A project by Andrea Asperti *)
-(* ||T|| *)
-(* ||I|| Developers: *)
-(* ||T|| The HELM team. *)
-(* ||A|| http://helm.cs.unibo.it *)
-(* \ / *)
-(* \ / This file is distributed under the terms of the *)
-(* v GNU General Public License Version 2 *)
-(* *)
-(**************************************************************************)
-
-include "ground_2/notation/relations/isidentity_1.ma".
-include "ground_2/relocation/trace_after.ma".
-include "ground_2/relocation/trace_sle.ma".
-
-(* RELOCATION TRACE *********************************************************)
-
-definition isid: predicate trace ≝ λcs. ∥cs∥ = |cs|.
-
-interpretation "test for identity (trace)"
- 'IsIdentity cs = (isid cs).
-
-definition t_reflexive: ∀S:Type[0]. predicate (trace → relation S) ≝
- λS,R. ∀a. ∃∃t. 𝐈⦃t⦄ & R t a a.
-
-(* Basic properties *********************************************************)
-
-lemma isid_empty: 𝐈⦃◊⦄.
-// qed.
-
-lemma isid_true: ∀cs. 𝐈⦃cs⦄ → 𝐈⦃Ⓣ @ cs⦄.
-// qed.
-
-(* Basic inversion lemmas ***************************************************)
-
-lemma isid_inv_true: ∀cs. 𝐈⦃Ⓣ @ cs⦄ → 𝐈⦃cs⦄.
-/2 width=1 by injective_S/ qed-.
-
-lemma isid_inv_false: ∀cs. 𝐈⦃Ⓕ @ cs⦄ → ⊥.
-/3 width=4 by colength_le, lt_le_false/ qed-.
-
-lemma isid_inv_cons: ∀cs,b. 𝐈⦃b @ cs⦄ → 𝐈⦃cs⦄ ∧ b = Ⓣ.
-#cs * #H /3 width=1 by isid_inv_true, conj/
-elim (isid_inv_false … H)
-qed-.
-
-(* Properties on application ************************************************)
-
-lemma isid_at: ∀cs. (∀i1,i2. @⦃i1, cs⦄ ≡ i2 → i1 = i2) → 𝐈⦃cs⦄.
-#cs elim cs -cs // * /2 width=1 by/
-qed.
-
-(* Inversion lemmas on application ******************************************)
-
-lemma isid_inv_at: ∀cs,i1,i2. @⦃i1, cs⦄ ≡ i2 → 𝐈⦃cs⦄ → i1 = i2.
-#cs #i1 #i2 #H elim H -cs -i1 -i2 /4 width=1 by isid_inv_true, eq_f/
-#cs #i1 #i2 #_ #IH #H elim (isid_inv_false … H)
-qed-.
-
-(* Properties on composition ************************************************)
-
-lemma isid_after_sn: ∀cs2. ∃∃cs1. 𝐈⦃cs1⦄ & cs1 ⊚ cs2 ≡ cs2.
-#cs2 elim cs2 -cs2 /2 width=3 by after_empty, ex2_intro/
-#b #cs2 * /3 width=3 by isid_true, after_true, ex2_intro/
-qed-.
-
-lemma isid_after_dx: ∀cs1. ∃∃cs2. 𝐈⦃cs2⦄ & cs1 ⊚ cs2 ≡ cs1.
-#cs1 elim cs1 -cs1 /2 width=3 by after_empty, ex2_intro/
-* #cs1 * /3 width=3 by isid_true, after_true, after_false, ex2_intro/
-qed-.
-
-lemma after_isid_sn: ∀cs1,cs2. cs1 ⊚ cs2 ≡ cs2 → 𝐈⦃cs1⦄ .
-#cs1 #cs2 #H elim (after_inv_length … H) -H //
-qed.
-
-lemma after_isid_dx: ∀cs1,cs2. cs1 ⊚ cs2 ≡ cs1 → 𝐈⦃cs2⦄ .
-#cs1 #cs2 #H elim (after_inv_length … H) -H //
-qed.
-
-(* Inversion lemmas on composition ******************************************)
-
-lemma after_isid_inv_sn: ∀cs1,cs2,cs. cs1 ⊚ cs2 ≡ cs → 𝐈⦃cs1⦄ → cs = cs2.
-#cs1 #cs2 #cs #H elim H -cs1 -cs2 -cs //
-#cs1 #cs2 #cs #_ [ #b ] #IH #H
-[ >IH -IH // | elim (isid_inv_false … H) ]
-qed-.
-
-lemma after_isid_inv_dx: ∀cs1,cs2,cs. cs1 ⊚ cs2 ≡ cs → 𝐈⦃cs2⦄ → cs = cs1.
-#cs1 #cs2 #cs #H elim H -cs1 -cs2 -cs //
-#cs1 #cs2 #cs #_ [ #b ] #IH #H
-[ elim (isid_inv_cons … H) -H #H >IH -IH // | >IH -IH // ]
-qed-.
-
-lemma after_inv_isid3: ∀t1,t2,t. t1 ⊚ t2 ≡ t → 𝐈⦃t⦄ → 𝐈⦃t1⦄ ∧ 𝐈⦃t2⦄.
-#t1 #t2 #t #H elim H -t1 -t2 -t
-[ /2 width=1 by conj/
-| #t1 #t2 #t #_ #b #IHt #H elim (isid_inv_cons … H) -H
- #Ht #H elim (IHt Ht) -t /2 width=1 by isid_true, conj/
-| #t1 #t2 #t #_ #_ #H elim (isid_inv_false … H)
-]
-qed-.
-
-(* Forward on inclusion *****************************************************)
-
-lemma sle_isid1_fwd: ∀t1,t2. t1 ⊆ t2 → 𝐈⦃t1⦄ → t1 = t2.
-#t1 #t2 #H elim H -t1 -t2 //
-[ #t1 #t2 #_ #IH #H lapply (isid_inv_true … H) -H
- #HT1 @eq_f2 // @IH @HT1 (**) (* full auto fails *)
-| #t1 #t2 #b #_ #_ #H elim (isid_inv_false … H)
-]
-qed-.