+++ /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 *)
-(* *)
-(**************************************************************************)
-
-notation "hvbox( L ⊢ break term 46 T1 ≈ break term 46 T2 )"
- non associative with precedence 45
- for @{ 'Hom $L $T1 $T2 }.
-
-notation "hvbox( L ⊢ break 𝐇𝐑 ⦃ term 46 T ⦄ )"
- non associative with precedence 45
- for @{ 'HdReducible $L $T }.
-
-notation "hvbox( L ⊢ break 𝐇𝐈 ⦃ term 46 T ⦄ )"
- non associative with precedence 45
- for @{ 'NotHdReducible $L $T }.
-
-include "basic_2/grammar/term_simple.ma".
-
-(* SAME HEAD TERM FORMS *****************************************************)
-
-inductive tshf: relation term ≝
- | tshf_atom: ∀I. tshf (⓪{I}) (⓪{I})
- | tshf_abbr: ∀V1,V2,T1,T2. tshf (-ⓓV1. T1) (-ⓓV2. T2)
- | tshf_abst: ∀a,V1,V2,T1,T2. tshf (ⓛ{a}V1. T1) (ⓛ{a}V2. T2)
- | tshf_appl: ∀V1,V2,T1,T2. tshf T1 T2 → 𝐒⦃T1⦄ → 𝐒⦃T2⦄ →
- tshf (ⓐV1. T1) (ⓐV2. T2)
-.
-
-interpretation "same head form (term)" 'napart T1 T2 = (tshf T1 T2).
-
-(* Basic properties *********************************************************)
-
-lemma tshf_sym: ∀T1,T2. T1 ≈ T2 → T2 ≈ T1.
-#T1 #T2 #H elim H -T1 -T2 /2 width=1/
-qed.
-
-lemma tshf_refl2: ∀T1,T2. T1 ≈ T2 → T2 ≈ T2.
-#T1 #T2 #H elim H -T1 -T2 // /2 width=1/
-qed.
-
-lemma tshf_refl1: ∀T1,T2. T1 ≈ T2 → T1 ≈ T1.
-/3 width=2/ qed.
-
-lemma simple_tshf_repl_dx: ∀T1,T2. T1 ≈ T2 → 𝐒⦃T1⦄ → 𝐒⦃T2⦄.
-#T1 #T2 #H elim H -T1 -T2 //
-[ #V1 #V2 #T1 #T2 #H
- elim (simple_inv_bind … H)
-| #a #V1 #V2 #T1 #T2 #H
- elim (simple_inv_bind … H)
-]
-qed. (**) (* remove from index *)
-
-lemma simple_tshf_repl_sn: ∀T1,T2. T1 ≈ T2 → 𝐒⦃T2⦄ → 𝐒⦃T1⦄.
-/3 width=3/ qed-.
-
-(* Basic inversion lemmas ***************************************************)
-
-fact tshf_inv_bind1_aux: ∀T1,T2. T1 ≈ T2 → ∀a,I,W1,U1. T1 = ⓑ{a,I}W1.U1 →
- ∃∃W2,U2. T2 = ⓑ{a,I}W2. U2 &
- (Bind2 a I = Bind2 false Abbr ∨ I = Abst).
-#T1 #T2 * -T1 -T2
-[ #J #a #I #W1 #U1 #H destruct
-| #V1 #V2 #T1 #T2 #a #I #W1 #U1 #H destruct /3 width=3/
-| #b #V1 #V2 #T1 #T2 #a #I #W1 #U1 #H destruct /3 width=3/
-| #V1 #V2 #T1 #T2 #_ #_ #_ #a #I #W1 #U1 #H destruct
-]
-qed.
-
-lemma tshf_inv_bind1: ∀a,I,W1,U1,T2. ⓑ{a,I}W1.U1 ≈ T2 →
- ∃∃W2,U2. T2 = ⓑ{a,I}W2. U2 &
- (Bind2 a I = Bind2 false Abbr ∨ I = Abst).
-/2 width=5/ qed-.
-
-fact tshf_inv_flat1_aux: ∀T1,T2. T1 ≈ T2 → ∀I,W1,U1. T1 = ⓕ{I}W1.U1 →
- ∃∃W2,U2. U1 ≈ U2 & 𝐒⦃U1⦄ & 𝐒⦃U2⦄ &
- I = Appl & T2 = ⓐW2. U2.
-#T1 #T2 * -T1 -T2
-[ #J #I #W1 #U1 #H destruct
-| #V1 #V2 #T1 #T2 #I #W1 #U1 #H destruct
-| #a #V1 #V2 #T1 #T2 #I #W1 #U1 #H destruct
-| #V1 #V2 #T1 #T2 #HT12 #HT1 #HT2 #I #W1 #U1 #H destruct /2 width=5/
-]
-qed.
-
-lemma tshf_inv_flat1: ∀I,W1,U1,T2. ⓕ{I}W1.U1 ≈ T2 →
- ∃∃W2,U2. U1 ≈ U2 & 𝐒⦃U1⦄ & 𝐒⦃U2⦄ &
- I = Appl & T2 = ⓐW2. U2.
-/2 width=4/ qed-.