+++ /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 *)
-(* *)
-(**************************************************************************)
-
-(* Initial invocation: - Patience on us to gain peace and perfection! - *)
-
-include "preamble.ma".
-
-(* TERM STRUCTURE ***********************************************************)
-
-(* Policy: term metavariables : A, B, C, D, M, N
- depth metavariables: i, j
-*)
-inductive term: Type[0] ≝
-| VRef: nat → term (* variable reference by depth *)
-| Abst: term → term (* function formation *)
-| Appl: term → term → term (* function application *)
-.
-
-interpretation "term construction (variable reference by index)"
- 'VariableReferenceByIndex i = (VRef i).
-
-interpretation "term construction (abstraction)"
- 'Abstraction A = (Abst A).
-
-interpretation "term construction (application)"
- 'Application C A = (Appl C A).
-
-notation "hvbox( # term 90 i )"
- non associative with precedence 90
- for @{ 'VariableReferenceByIndex $i }.
-
-notation "hvbox( 𝛌 . term 46 A )"
- non associative with precedence 46
- for @{ 'Abstraction $A }.
-
-notation "hvbox( @ term 46 C . break term 46 A )"
- non associative with precedence 46
- for @{ 'Application $C $A }.
-
-definition compatible_abst: predicate (relation term) ≝ λR.
- ∀A1,A2. R A1 A2 → R (𝛌.A1) (𝛌.A2).
-
-definition compatible_sn: predicate (relation term) ≝ λR.
- ∀A,B1,B2. R B1 B2 → R (@B1.A) (@B2.A).
-
-definition compatible_dx: predicate (relation term) ≝ λR.
- ∀B,A1,A2. R A1 A2 → R (@B.A1) (@B.A2).
-
-definition compatible_appl: predicate (relation term) ≝ λR.
- ∀B1,B2. R B1 B2 → ∀A1,A2. R A1 A2 →
- R (@B1.A1) (@B2.A2).
-
-lemma star_compatible_abst: ∀R. compatible_abst R → compatible_abst (star … R).
-#R #HR #A1 #A2 #H elim H -A2 // /3 width=3/
-qed.
-
-lemma star_compatible_sn: ∀R. compatible_sn R → compatible_sn (star … R).
-#R #HR #A #B1 #B2 #H elim H -B2 // /3 width=3/
-qed.
-
-lemma star_compatible_dx: ∀R. compatible_dx R → compatible_dx (star … R).
-#R #HR #B #A1 #A2 #H elim H -A2 // /3 width=3/
-qed.
-
-lemma star_compatible_appl: ∀R. reflexive ? R →
- compatible_appl R → compatible_appl (star … R).
-#R #H1R #H2R #B1 #B2 #H elim H -B2 /3 width=1/ /3 width=5/
-qed.