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10 commits

Author SHA1 Message Date
3efca4160b Add noconf check 2025-02-28 16:39:10 -05:00
7b5e9f2562 view needs more information 2025-02-28 15:56:37 -05:00
816c73cb71 Switch to view pattern 2025-02-28 14:50:42 -05:00
ca73b5eac6 Add more cases to tm_to_eq 2025-02-28 14:42:40 -05:00
44ba3e6575 Add view 2025-02-28 14:05:26 -05:00
Yiyun Liu
11bfed2d17 Finish defining the algorithm 2025-02-28 00:30:02 -05:00
Yiyun Liu
757f050d92 The definition is semi-working 2025-02-27 22:27:16 -05:00
Yiyun Liu
7503dea251 Seems to work but takes a million years to type check 2025-02-27 21:33:25 -05:00
Yiyun Liu
6c11f5560d Need noconfusion? 2025-02-27 20:56:01 -05:00
Yiyun Liu
875db75955 Add equations for check_equal 2025-02-27 20:39:55 -05:00
6 changed files with 857 additions and 993 deletions

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@ -16,12 +16,12 @@ uninstall: $(COQMAKEFILE)
$(MAKE) -f $(COQMAKEFILE) uninstall
theories/Autosubst2/syntax.v theories/Autosubst2/core.v theories/Autosubst2/fintype.v : syntax.sig
autosubst -f -v ge813 -s coq -o theories/Autosubst2/syntax.v syntax.sig
autosubst -f -v ge813 -s ucoq -o theories/Autosubst2/syntax.v syntax.sig
.PHONY: clean FORCE
clean:
test ! -f $(COQMAKEFILE) || ( $(MAKE) -f $(COQMAKEFILE) clean && rm $(COQMAKEFILE) )
rm -f theories/Autosubst2/syntax.v theories/Autosubst2/core.v theories/Autosubst2/fintype.v
rm -f theories/Autosubst2/syntax.v theories/Autosubst2/core.v theories/Autosubst2/fintype.v theories/Autosubst2/unscoped.v
FORCE:

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@ -1,419 +0,0 @@
(** * Autosubst Header for Scoped Syntax
Our development utilises well-scoped de Bruijn syntax. This means that the de Bruijn indices are taken from finite types. As a consequence, any kind of substitution or environment used in conjunction with well-scoped syntax takes the form of a mapping from some finite type _I^n_. In particular, _renamings_ are mappings _I^n -> I^m_. Here we develop the theory of how these parts interact.
Version: December 11, 2019.
*)
Require Import core.
Require Import Setoid Morphisms Relation_Definitions.
Set Implicit Arguments.
Unset Strict Implicit.
Definition ap {X Y} (f : X -> Y) {x y : X} (p : x = y) : f x = f y :=
match p with eq_refl => eq_refl end.
Definition apc {X Y} {f g : X -> Y} {x y : X} (p : f = g) (q : x = y) : f x = g y :=
match q with eq_refl => match p with eq_refl => eq_refl end end.
(** ** Primitives of the Sigma Calculus
We implement the finite type with _n_ elements, _I^n_, as the _n_-fold iteration of the Option Type. _I^0_ is implemented as the empty type.
*)
Fixpoint fin (n : nat) : Type :=
match n with
| 0 => False
| S m => option (fin m)
end.
(** Renamings and Injective Renamings
_Renamings_ are mappings between finite types.
*)
Definition ren (m n : nat) : Type := fin m -> fin n.
Definition id {X} := @Datatypes.id X.
Definition idren {k: nat} : ren k k := @Datatypes.id (fin k).
(** We give a special name, to the newest element in a non-empty finite type, as it usually corresponds to a freshly bound variable. *)
Definition var_zero {n : nat} : fin (S n) := None.
Definition null {T} (i : fin 0) : T := match i with end.
Definition shift {n : nat} : ren n (S n) :=
Some.
(** Extension of Finite Mappings
Assume we are given a mapping _f_ from _I^n_ to some type _X_, then we can _extend_ this mapping with a new value from _x : X_ to a mapping from _I^n+1_ to _X_. We denote this operation by _x . f_ and define it as follows:
*)
Definition scons {X : Type} {n : nat} (x : X) (f : fin n -> X) (m : fin (S n)) : X :=
match m with
| None => x
| Some i => f i
end.
#[ export ]
Hint Opaque scons : rewrite.
(** ** Type Class Instances for Notation *)
(** *** Type classes for renamings. *)
Class Ren1 (X1 : Type) (Y Z : Type) :=
ren1 : X1 -> Y -> Z.
Class Ren2 (X1 X2 : Type) (Y Z : Type) :=
ren2 : X1 -> X2 -> Y -> Z.
Class Ren3 (X1 X2 X3 : Type) (Y Z : Type) :=
ren3 : X1 -> X2 -> X3 -> Y -> Z.
Class Ren4 (X1 X2 X3 X4 : Type) (Y Z : Type) :=
ren4 : X1 -> X2 -> X3 -> X4 -> Y -> Z.
Class Ren5 (X1 X2 X3 X4 X5 : Type) (Y Z : Type) :=
ren5 : X1 -> X2 -> X3 -> X4 -> X5 -> Y -> Z.
Module RenNotations.
Notation "s ⟨ xi1 ⟩" := (ren1 xi1 s) (at level 7, left associativity, format "s ⟨ xi1 ⟩") : subst_scope.
Notation "s ⟨ xi1 ; xi2 ⟩" := (ren2 xi1 xi2 s) (at level 7, left associativity, format "s ⟨ xi1 ; xi2 ⟩") : subst_scope.
Notation "s ⟨ xi1 ; xi2 ; xi3 ⟩" := (ren3 xi1 xi2 xi3 s) (at level 7, left associativity, format "s ⟨ xi1 ; xi2 ; xi3 ⟩") : subst_scope.
Notation "s ⟨ xi1 ; xi2 ; xi3 ; xi4 ⟩" := (ren4 xi1 xi2 xi3 xi4 s) (at level 7, left associativity, format "s ⟨ xi1 ; xi2 ; xi3 ; xi4 ⟩") : subst_scope.
Notation "s ⟨ xi1 ; xi2 ; xi3 ; xi4 ; xi5 ⟩" := (ren5 xi1 xi2 xi3 xi4 xi5 s) (at level 7, left associativity, format "s ⟨ xi1 ; xi2 ; xi3 ; xi4 ; xi5 ⟩") : subst_scope.
Notation "⟨ xi ⟩" := (ren1 xi) (at level 1, left associativity, format "⟨ xi ⟩") : fscope.
Notation "⟨ xi1 ; xi2 ⟩" := (ren2 xi1 xi2) (at level 1, left associativity, format "⟨ xi1 ; xi2 ⟩") : fscope.
End RenNotations.
(** *** Type Classes for Substiution *)
Class Subst1 (X1 : Type) (Y Z: Type) :=
subst1 : X1 -> Y -> Z.
Class Subst2 (X1 X2 : Type) (Y Z: Type) :=
subst2 : X1 -> X2 -> Y -> Z.
Class Subst3 (X1 X2 X3 : Type) (Y Z: Type) :=
subst3 : X1 -> X2 -> X3 -> Y -> Z.
Class Subst4 (X1 X2 X3 X4: Type) (Y Z: Type) :=
subst4 : X1 -> X2 -> X3 -> X4 -> Y -> Z.
Class Subst5 (X1 X2 X3 X4 X5 : Type) (Y Z: Type) :=
subst5 : X1 -> X2 -> X3 -> X4 -> X5 -> Y -> Z.
Module SubstNotations.
Notation "s [ sigma ]" := (subst1 sigma s) (at level 7, left associativity, format "s '/' [ sigma ]") : subst_scope.
Notation "s [ sigma ; tau ]" := (subst2 sigma tau s) (at level 7, left associativity, format "s '/' [ sigma ; '/' tau ]") : subst_scope.
End SubstNotations.
(** ** Type Class for Variables *)
Class Var X Y :=
ids : X -> Y.
(** ** Proofs for substitution primitives *)
(** Forward Function Composition
Substitutions represented as functions are ubiquitious in this development and we often have to compose them, without talking about their pointwise behaviour.
That is, we are interested in the forward compostion of functions, _f o g_, for which we introduce a convenient notation, "f >> g". The direction of the arrow serves as a reminder of the _forward_ nature of this composition, that is first apply _f_, then _g_. *)
Arguments funcomp {X Y Z} (g)%fscope (f)%fscope.
Module CombineNotations.
Notation "f >> g" := (funcomp g f) (at level 50) : fscope.
Notation "s .: sigma" := (scons s sigma) (at level 55, sigma at next level, right associativity) : subst_scope.
#[ global ]
Open Scope fscope.
#[ global ]
Open Scope subst_scope.
End CombineNotations.
Import CombineNotations.
(** Generic lifting operation for renamings *)
Definition up_ren {m n} (xi : ren m n) : ren (S m) (S n) :=
var_zero .: xi >> shift.
(** Generic proof that lifting of renamings composes. *)
Lemma up_ren_ren k l m (xi: ren k l) (zeta : ren l m) (rho: ren k m) (E: forall x, (xi >> zeta) x = rho x) :
forall x, (up_ren xi >> up_ren zeta) x = up_ren rho x.
Proof.
intros [x|].
- cbn. unfold funcomp. now rewrite <- E.
- reflexivity.
Qed.
Arguments up_ren_ren {k l m} xi zeta rho E.
Lemma fin_eta {X} (f g : fin 0 -> X) :
pointwise_relation _ eq f g.
Proof. intros []. Qed.
(** Eta laws *)
Lemma scons_eta' {T} {n : nat} (f : fin (S n) -> T) :
pointwise_relation _ eq (f var_zero .: (funcomp f shift)) f.
Proof. intros x. destruct x; reflexivity. Qed.
Lemma scons_eta_id' {n : nat} :
pointwise_relation (fin (S n)) eq (var_zero .: shift) id.
Proof. intros x. destruct x; reflexivity. Qed.
Lemma scons_comp' {T:Type} {U} {m} (s: T) (sigma: fin m -> T) (tau: T -> U) :
pointwise_relation _ eq (funcomp tau (s .: sigma)) ((tau s) .: (funcomp tau sigma)).
Proof. intros x. destruct x; reflexivity. Qed.
(* Lemma scons_tail'_pointwise {X} {n} (s : X) (f : fin n -> X) : *)
(* pointwise_relation _ eq (funcomp (scons s f) shift) f. *)
(* Proof. *)
(* reflexivity. *)
(* Qed. *)
(* Lemma scons_tail' {X} {n} (s : X) (f : fin n -> X) x : *)
(* (scons s f (shift x)) = f x. *)
(* Proof. *)
(* reflexivity. *)
(* Qed. *)
(* Morphism for Setoid Rewriting. The only morphism that can be defined statically. *)
#[export] Instance scons_morphism {X: Type} {n:nat} :
Proper (eq ==> pointwise_relation _ eq ==> pointwise_relation _ eq) (@scons X n).
Proof.
intros t t' -> sigma tau H.
intros [x|].
cbn. apply H.
reflexivity.
Qed.
#[export] Instance scons_morphism2 {X: Type} {n: nat} :
Proper (eq ==> pointwise_relation _ eq ==> eq ==> eq) (@scons X n).
Proof.
intros ? t -> sigma tau H ? x ->.
destruct x as [x|].
cbn. apply H.
reflexivity.
Qed.
(** ** Variadic Substitution Primitives *)
Fixpoint shift_p (p : nat) {n} : ren n (p + n) :=
fun n => match p with
| 0 => n
| S p => Some (shift_p p n)
end.
Fixpoint scons_p {X: Type} {m : nat} : forall {n} (f : fin m -> X) (g : fin n -> X), fin (m + n) -> X.
Proof.
destruct m.
- intros n f g. exact g.
- intros n f g. cbn. apply scons.
+ exact (f var_zero).
+ apply scons_p.
* intros z. exact (f (Some z)).
* exact g.
Defined.
#[export] Hint Opaque scons_p : rewrite.
#[export] Instance scons_p_morphism {X: Type} {m n:nat} :
Proper (pointwise_relation _ eq ==> pointwise_relation _ eq ==> pointwise_relation _ eq) (@scons_p X m n).
Proof.
intros sigma sigma' Hsigma tau tau' Htau.
intros x.
induction m.
- cbn. apply Htau.
- cbn. change (fin (S m + n)) with (fin (S (m + n))) in x.
destruct x as [x|].
+ cbn. apply IHm.
intros ?. apply Hsigma.
+ cbn. apply Hsigma.
Qed.
#[export] Instance scons_p_morphism2 {X: Type} {m n:nat} :
Proper (pointwise_relation _ eq ==> pointwise_relation _ eq ==> eq ==> eq) (@scons_p X m n).
Proof.
intros sigma sigma' Hsigma tau tau' Htau ? x ->.
induction m.
- cbn. apply Htau.
- cbn. change (fin (S m + n)) with (fin (S (m + n))) in x.
destruct x as [x|].
+ cbn. apply IHm.
intros ?. apply Hsigma.
+ cbn. apply Hsigma.
Qed.
Definition zero_p {m : nat} {n} : fin m -> fin (m + n).
Proof.
induction m.
- intros [].
- intros [x|].
+ exact (shift_p 1 (IHm x)).
+ exact var_zero.
Defined.
Lemma scons_p_head' {X} {m n} (f : fin m -> X) (g : fin n -> X) z:
(scons_p f g) (zero_p z) = f z.
Proof.
induction m.
- inversion z.
- destruct z.
+ simpl. simpl. now rewrite IHm.
+ reflexivity.
Qed.
Lemma scons_p_head_pointwise {X} {m n} (f : fin m -> X) (g : fin n -> X) :
pointwise_relation _ eq (funcomp (scons_p f g) zero_p) f.
Proof.
intros z.
unfold funcomp.
induction m.
- inversion z.
- destruct z.
+ simpl. now rewrite IHm.
+ reflexivity.
Qed.
Lemma scons_p_tail' X m n (f : fin m -> X) (g : fin n -> X) z :
scons_p f g (shift_p m z) = g z.
Proof. induction m; cbn; eauto. Qed.
Lemma scons_p_tail_pointwise X m n (f : fin m -> X) (g : fin n -> X) :
pointwise_relation _ eq (funcomp (scons_p f g) (shift_p m)) g.
Proof. intros z. induction m; cbn; eauto. Qed.
Lemma destruct_fin {m n} (x : fin (m + n)):
(exists x', x = zero_p x') \/ exists x', x = shift_p m x'.
Proof.
induction m; simpl in *.
- right. eauto.
- destruct x as [x|].
+ destruct (IHm x) as [[x' ->] |[x' ->]].
* left. now exists (Some x').
* right. eauto.
+ left. exists None. eauto.
Qed.
Lemma scons_p_comp' X Y m n (f : fin m -> X) (g : fin n -> X) (h : X -> Y) :
pointwise_relation _ eq (funcomp h (scons_p f g)) (scons_p (f >> h) (g >> h)).
Proof.
intros x.
destruct (destruct_fin x) as [[x' ->]|[x' ->]].
(* TODO better way to solve this? *)
- revert x'.
apply pointwise_forall.
change (fun x => (scons_p f g >> h) (zero_p x)) with (zero_p >> scons_p f g >> h).
now setoid_rewrite scons_p_head_pointwise.
- revert x'.
apply pointwise_forall.
change (fun x => (scons_p f g >> h) (shift_p m x)) with (shift_p m >> scons_p f g >> h).
change (fun x => scons_p (f >> h) (g >> h) (shift_p m x)) with (shift_p m >> scons_p (f >> h) (g >> h)).
now rewrite !scons_p_tail_pointwise.
Qed.
Lemma scons_p_congr {X} {m n} (f f' : fin m -> X) (g g': fin n -> X) z:
(forall x, f x = f' x) -> (forall x, g x = g' x) -> scons_p f g z = scons_p f' g' z.
Proof. intros H1 H2. induction m; eauto. cbn. destruct z; eauto. Qed.
(** Generic n-ary lifting operation. *)
Definition upRen_p p { m : nat } { n : nat } (xi : (fin) (m) -> (fin) (n)) : fin (p + m) -> fin (p + n) :=
scons_p (zero_p ) (xi >> shift_p _).
Arguments upRen_p p {m n} xi.
(** Generic proof for composition of n-ary lifting. *)
Lemma up_ren_ren_p p k l m (xi: ren k l) (zeta : ren l m) (rho: ren k m) (E: forall x, (xi >> zeta) x = rho x) :
forall x, (upRen_p p xi >> upRen_p p zeta) x = upRen_p p rho x.
Proof.
intros x. destruct (destruct_fin x) as [[? ->]|[? ->]].
- unfold upRen_p. unfold funcomp. now repeat rewrite scons_p_head'.
- unfold upRen_p. unfold funcomp. repeat rewrite scons_p_tail'.
now rewrite <- E.
Qed.
Arguments zero_p m {n}.
Arguments scons_p {X} m {n} f g.
Lemma scons_p_eta {X} {m n} {f : fin m -> X}
{g : fin n -> X} (h: fin (m + n) -> X) {z: fin (m + n)}:
(forall x, g x = h (shift_p m x)) -> (forall x, f x = h (zero_p m x)) -> scons_p m f g z = h z.
Proof.
intros H1 H2. destruct (destruct_fin z) as [[? ->] |[? ->]].
- rewrite scons_p_head'. eauto.
- rewrite scons_p_tail'. eauto.
Qed.
Arguments scons_p_eta {X} {m n} {f g} h {z}.
Arguments scons_p_congr {X} {m n} {f f'} {g g'} {z}.
(** ** Notations for Scoped Syntax *)
Module ScopedNotations.
Include RenNotations.
Include SubstNotations.
Include CombineNotations.
(* Notation "s , sigma" := (scons s sigma) (at level 60, format "s , sigma", right associativity) : subst_scope. *)
Notation "s '..'" := (scons s ids) (at level 1, format "s ..") : subst_scope.
Notation "" := (shift) : subst_scope.
#[global]
Open Scope fscope.
#[global]
Open Scope subst_scope.
End ScopedNotations.
(** ** Tactics for Scoped Syntax *)
Tactic Notation "auto_case" tactic(t) := (match goal with
| [|- forall (i : fin 0), _] => intros []; t
| [|- forall (i : fin (S (S (S (S _))))), _] => intros [[[[|]|]|]|]; t
| [|- forall (i : fin (S (S (S _)))), _] => intros [[[|]|]|]; t
| [|- forall (i : fin (S (S _))), _] => intros [[?|]|]; t
| [|- forall (i : fin (S _)), _] => intros [?|]; t
end).
#[export] Hint Rewrite @scons_p_head' @scons_p_tail' : FunctorInstances.
(** Generic fsimpl tactic: simplifies the above primitives in a goal. *)
Ltac fsimpl :=
repeat match goal with
| [|- context[id >> ?f]] => change (id >> f) with f (* AsimplCompIdL *)
| [|- context[?f >> id]] => change (f >> id) with f (* AsimplCompIdR *)
| [|- context [id ?s]] => change (id s) with s
| [|- context[(?f >> ?g) >> ?h]] => change ((f >> g) >> h) with (f >> (g >> h)) (* AsimplComp *)
(* | [|- zero_p >> scons_p ?f ?g] => rewrite scons_p_head *)
| [|- context[(?s .: ?sigma) var_zero]] => change ((s.:sigma) var_zero) with s
| [|- context[(?s .: ?sigma) (shift ?m)]] => change ((s.:sigma) (shift m)) with (sigma m)
(* first [progress setoid_rewrite scons_tail' | progress setoid_rewrite scons_tail'_pointwise ] *)
| [|- context[idren >> ?f]] => change (idren >> f) with f
| [|- context[?f >> idren]] => change (f >> idren) with f
| [|- context[?f >> (?x .: ?g)]] => change (f >> (x .: g)) with g (* f should evaluate to shift *)
| [|- context[?x2 .: (funcomp ?f shift)]] => change (scons x2 (funcomp f shift)) with (scons (f var_zero) (funcomp f shift)); setoid_rewrite (@scons_eta' _ _ f); eta_reduce
| [|- context[?f var_zero .: ?g]] => change (scons (f var_zero) g) with (scons (f var_zero) (funcomp f shift)); setoid_rewrite scons_eta'; eta_reduce
| [|- _ = ?h (?f ?s)] => change (h (f s)) with ((f >> h) s)
| [|- ?h (?f ?s) = _] => change (h (f s)) with ((f >> h) s)
| [|- context[funcomp _ (scons _ _)]] => setoid_rewrite scons_comp'; eta_reduce
| [|- context[funcomp _ (scons_p _ _ _)]] => setoid_rewrite scons_p_comp'; eta_reduce
| [|- context[scons (@var_zero _) shift]] => setoid_rewrite scons_eta_id'; eta_reduce
(* | _ => progress autorewrite with FunctorInstances *)
| [|- context[funcomp (scons_p _ _ _) (zero_p _)]] =>
first [progress setoid_rewrite scons_p_head_pointwise | progress setoid_rewrite scons_p_head' ]
| [|- context[scons_p _ _ _ (zero_p _ _)]] => setoid_rewrite scons_p_head'
| [|- context[funcomp (scons_p _ _ _) (shift_p _)]] =>
first [progress setoid_rewrite scons_p_tail_pointwise | progress setoid_rewrite scons_p_tail' ]
| [|- context[scons_p _ _ _ (shift_p _ _)]] => setoid_rewrite scons_p_tail'
| _ => first [progress minimize | progress cbn [shift scons scons_p] ]
end.

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(** * Autosubst Header for Unnamed Syntax
Version: December 11, 2019.
*)
(* Adrian:
I changed this library a bit to work better with my generated code.
1. I use nat directly instead of defining fin to be nat and using Some/None as S/O
2. I removed the "s, sigma" notation for scons because it interacts with dependent function types "forall x, A"*)
Require Import core.
Require Import Setoid Morphisms Relation_Definitions.
Definition ap {X Y} (f : X -> Y) {x y : X} (p : x = y) : f x = f y :=
match p with eq_refl => eq_refl end.
Definition apc {X Y} {f g : X -> Y} {x y : X} (p : f = g) (q : x = y) : f x = g y :=
match q with eq_refl => match p with eq_refl => eq_refl end end.
(** ** Primitives of the Sigma Calculus. *)
Definition shift := S.
Definition var_zero := 0.
Definition id {X} := @Datatypes.id X.
Definition scons {X: Type} (x : X) (xi : nat -> X) :=
fun n => match n with
| 0 => x
| S n => xi n
end.
#[ export ]
Hint Opaque scons : rewrite.
(** ** Type Class Instances for Notation
Required to make notation work. *)
(** *** Type classes for renamings. *)
Class Ren1 (X1 : Type) (Y Z : Type) :=
ren1 : X1 -> Y -> Z.
Class Ren2 (X1 X2 : Type) (Y Z : Type) :=
ren2 : X1 -> X2 -> Y -> Z.
Class Ren3 (X1 X2 X3 : Type) (Y Z : Type) :=
ren3 : X1 -> X2 -> X3 -> Y -> Z.
Class Ren4 (X1 X2 X3 X4 : Type) (Y Z : Type) :=
ren4 : X1 -> X2 -> X3 -> X4 -> Y -> Z.
Class Ren5 (X1 X2 X3 X4 X5 : Type) (Y Z : Type) :=
ren5 : X1 -> X2 -> X3 -> X4 -> X5 -> Y -> Z.
Module RenNotations.
Notation "s ⟨ xi1 ⟩" := (ren1 xi1 s) (at level 7, left associativity, format "s ⟨ xi1 ⟩") : subst_scope.
Notation "s ⟨ xi1 ; xi2 ⟩" := (ren2 xi1 xi2 s) (at level 7, left associativity, format "s ⟨ xi1 ; xi2 ⟩") : subst_scope.
Notation "s ⟨ xi1 ; xi2 ; xi3 ⟩" := (ren3 xi1 xi2 xi3 s) (at level 7, left associativity, format "s ⟨ xi1 ; xi2 ; xi3 ⟩") : subst_scope.
Notation "s ⟨ xi1 ; xi2 ; xi3 ; xi4 ⟩" := (ren4 xi1 xi2 xi3 xi4 s) (at level 7, left associativity, format "s ⟨ xi1 ; xi2 ; xi3 ; xi4 ⟩") : subst_scope.
Notation "s ⟨ xi1 ; xi2 ; xi3 ; xi4 ; xi5 ⟩" := (ren5 xi1 xi2 xi3 xi4 xi5 s) (at level 7, left associativity, format "s ⟨ xi1 ; xi2 ; xi3 ; xi4 ; xi5 ⟩") : subst_scope.
Notation "⟨ xi ⟩" := (ren1 xi) (at level 1, left associativity, format "⟨ xi ⟩") : fscope.
Notation "⟨ xi1 ; xi2 ⟩" := (ren2 xi1 xi2) (at level 1, left associativity, format "⟨ xi1 ; xi2 ⟩") : fscope.
End RenNotations.
(** *** Type Classes for Substiution *)
Class Subst1 (X1 : Type) (Y Z: Type) :=
subst1 : X1 -> Y -> Z.
Class Subst2 (X1 X2 : Type) (Y Z: Type) :=
subst2 : X1 -> X2 -> Y -> Z.
Class Subst3 (X1 X2 X3 : Type) (Y Z: Type) :=
subst3 : X1 -> X2 -> X3 -> Y -> Z.
Class Subst4 (X1 X2 X3 X4: Type) (Y Z: Type) :=
subst4 : X1 -> X2 -> X3 -> X4 -> Y -> Z.
Class Subst5 (X1 X2 X3 X4 X5 : Type) (Y Z: Type) :=
subst5 : X1 -> X2 -> X3 -> X4 -> X5 -> Y -> Z.
Module SubstNotations.
Notation "s [ sigma ]" := (subst1 sigma s) (at level 7, left associativity, format "s '/' [ sigma ]") : subst_scope.
Notation "s [ sigma ; tau ]" := (subst2 sigma tau s) (at level 7, left associativity, format "s '/' [ sigma ; '/' tau ]") : subst_scope.
End SubstNotations.
(** *** Type Class for Variables *)
Class Var X Y :=
ids : X -> Y.
#[export] Instance idsRen : Var nat nat := id.
(** ** Proofs for the substitution primitives. *)
Arguments funcomp {X Y Z} (g)%fscope (f)%fscope.
Module CombineNotations.
Notation "f >> g" := (funcomp g f) (at level 50) : fscope.
Notation "s .: sigma" := (scons s sigma) (at level 55, sigma at next level, right associativity) : subst_scope.
#[ global ]
Open Scope fscope.
#[ global ]
Open Scope subst_scope.
End CombineNotations.
Import CombineNotations.
(** A generic lifting of a renaming. *)
Definition up_ren (xi : nat -> nat) :=
0 .: (xi >> S).
(** A generic proof that lifting of renamings composes. *)
Lemma up_ren_ren (xi: nat -> nat) (zeta : nat -> nat) (rho: nat -> nat) (E: forall x, (xi >> zeta) x = rho x) :
forall x, (up_ren xi >> up_ren zeta) x = up_ren rho x.
Proof.
intros [|x].
- reflexivity.
- unfold up_ren. cbn. unfold funcomp. f_equal. apply E.
Qed.
(** Eta laws. *)
Lemma scons_eta' {T} (f : nat -> T) :
pointwise_relation _ eq (f var_zero .: (funcomp f shift)) f.
Proof. intros x. destruct x; reflexivity. Qed.
Lemma scons_eta_id' :
pointwise_relation _ eq (var_zero .: shift) id.
Proof. intros x. destruct x; reflexivity. Qed.
Lemma scons_comp' (T: Type) {U} (s: T) (sigma: nat -> T) (tau: T -> U) :
pointwise_relation _ eq (funcomp tau (s .: sigma)) ((tau s) .: (funcomp tau sigma)).
Proof. intros x. destruct x; reflexivity. Qed.
(* Morphism for Setoid Rewriting. The only morphism that can be defined statically. *)
#[export] Instance scons_morphism {X: Type} :
Proper (eq ==> pointwise_relation _ eq ==> pointwise_relation _ eq) (@scons X).
Proof.
intros ? t -> sigma tau H.
intros [|x].
cbn. reflexivity.
apply H.
Qed.
#[export] Instance scons_morphism2 {X: Type} :
Proper (eq ==> pointwise_relation _ eq ==> eq ==> eq) (@scons X).
Proof.
intros ? t -> sigma tau H ? x ->.
destruct x as [|x].
cbn. reflexivity.
apply H.
Qed.
(** ** Generic lifting of an allfv predicate *)
Definition up_allfv (p: nat -> Prop) : nat -> Prop := scons True p.
(** ** Notations for unscoped syntax *)
Module UnscopedNotations.
Include RenNotations.
Include SubstNotations.
Include CombineNotations.
(* Notation "s , sigma" := (scons s sigma) (at level 60, format "s , sigma", right associativity) : subst_scope. *)
Notation "s '..'" := (scons s ids) (at level 1, format "s ..") : subst_scope.
Notation "" := (shift) : subst_scope.
#[global]
Open Scope fscope.
#[global]
Open Scope subst_scope.
End UnscopedNotations.
(** ** Tactics for unscoped syntax *)
(** Automatically does a case analysis on a natural number, useful for proofs with context renamings/context morphisms. *)
Tactic Notation "auto_case" tactic(t) := (match goal with
| [|- forall (i : nat), _] => intros []; t
end).
(** Generic fsimpl tactic: simplifies the above primitives in a goal. *)
Ltac fsimpl :=
repeat match goal with
| [|- context[id >> ?f]] => change (id >> f) with f (* AsimplCompIdL *)
| [|- context[?f >> id]] => change (f >> id) with f (* AsimplCompIdR *)
| [|- context [id ?s]] => change (id s) with s
| [|- context[(?f >> ?g) >> ?h]] => change ((f >> g) >> h) with (f >> (g >> h))
| [|- context[(?v .: ?g) var_zero]] => change ((v .: g) var_zero) with v
| [|- context[(?v .: ?g) 0]] => change ((v .: g) 0) with v
| [|- context[(?v .: ?g) (S ?n)]] => change ((v .: g) (S n)) with (g n)
| [|- context[?f >> (?x .: ?g)]] => change (f >> (x .: g)) with g (* f should evaluate to shift *)
| [|- context[var_zero]] => change var_zero with 0
| [|- context[?x2 .: (funcomp ?f shift)]] => change (scons x2 (funcomp f shift)) with (scons (f var_zero) (funcomp f shift)); setoid_rewrite (@scons_eta' _ _ f)
| [|- context[?f var_zero .: ?g]] => change (scons (f var_zero) g) with (scons (f var_zero) (funcomp f shift)); rewrite scons_eta'
| [|- _ = ?h (?f ?s)] => change (h (f s)) with ((f >> h) s)
| [|- ?h (?f ?s) = _] => change (h (f s)) with ((f >> h) s)
(* DONE had to put an underscore as the last argument to scons. This might be an argument against unfolding funcomp *)
| [|- context[funcomp _ (scons _ _)]] => setoid_rewrite scons_comp'; eta_reduce
| [|- context[scons var_zero shift]] => setoid_rewrite scons_eta_id'; eta_reduce
end.

View file

@ -4,6 +4,7 @@ Import Ltac2.Notations.
Import Ltac2.Control.
From Hammer Require Import Tactics.
Definition renaming_ok {n m} (Γ : fin n -> PTm n) (Δ : fin m -> PTm m) (ξ : fin m -> fin n) :=
forall (i : fin m), ren_PTm ξ (Δ i) = Γ (ξ i).

View file

@ -1,58 +1,221 @@
From Equations Require Import Equations.
Require Import Autosubst2.core Autosubst2.fintype Autosubst2.syntax
common typing preservation admissible fp_red structural soundness.
Require Import algorithmic.
From stdpp Require Import relations (rtc(..), nsteps(..)).
Require Import ssreflect ssrbool.
Require Import Autosubst2.core Autosubst2.unscoped Autosubst2.syntax.
Derive NoConfusion for option sig nat PTag BTag PTm.
Derive EqDec for BTag PTag PTm.
Import Logic (inspect).
Require Import Cdcl.Itauto.
Inductive algo_dom {n} : PTm n -> PTm n -> Prop :=
Require Import ssreflect ssrbool.
From Hammer Require Import Tactics.
Definition ishf (a : PTm) :=
match a with
| PPair _ _ => true
| PAbs _ => true
| PUniv _ => true
| PBind _ _ _ => true
| PNat => true
| PSuc _ => true
| PZero => true
| _ => false
end.
Fixpoint ishne (a : PTm) :=
match a with
| VarPTm _ => true
| PApp a _ => ishne a
| PProj _ a => ishne a
| PBot => true
| PInd _ n _ _ => ishne n
| _ => false
end.
Module HRed.
Inductive R : PTm -> PTm -> Prop :=
(****************** Beta ***********************)
| AppAbs a b :
R (PApp (PAbs a) b) (subst_PTm (scons b VarPTm) a)
| ProjPair p a b :
R (PProj p (PPair a b)) (if p is PL then a else b)
| IndZero P b c :
R (PInd P PZero b c) b
| IndSuc P a b c :
R (PInd P (PSuc a) b c) (subst_PTm (scons (PInd P a b c) (scons a VarPTm)) c)
(*************** Congruence ********************)
| AppCong a0 a1 b :
R a0 a1 ->
R (PApp a0 b) (PApp a1 b)
| ProjCong p a0 a1 :
R a0 a1 ->
R (PProj p a0) (PProj p a1)
| IndCong P a0 a1 b c :
R a0 a1 ->
R (PInd P a0 b c) (PInd P a1 b c).
Definition nf a := forall b, ~ R a b.
End HRed.
Definition isbind (a : PTm) := if a is PBind _ _ _ then true else false.
Definition isuniv (a : PTm) := if a is PUniv _ then true else false.
Definition ispair (a : PTm) :=
match a with
| PPair _ _ => true
| _ => false
end.
Definition isnat (a : PTm) := if a is PNat then true else false.
Definition iszero (a : PTm) := if a is PZero then true else false.
Definition issuc (a : PTm) := if a is PSuc _ then true else false.
Definition isabs (a : PTm) :=
match a with
| PAbs _ => true
| _ => false
end.
Definition tm_nonconf (a b : PTm) : bool :=
match a, b with
| PAbs _, _ => ishne b || isabs b
| _, PAbs _ => ishne a
| VarPTm _, VarPTm _ => true
| PPair _ _, _ => ishne b || ispair b
| _, PPair _ _ => ishne a
| PZero, PZero => true
| PSuc _, PSuc _ => true
| PApp _ _, PApp _ _ => ishne a && ishne b
| PProj _ _, PProj _ _ => ishne a && ishne b
| PInd _ _ _ _, PInd _ _ _ _ => ishne a && ishne b
| PNat, PNat => true
| PUniv _, PUniv _ => true
| PBind _ _ _, PBind _ _ _ => true
| _,_=> false
end.
Definition tm_conf (a b : PTm) := ~~ tm_nonconf a b.
Inductive eq_view : PTm -> PTm -> Type :=
| V_AbsAbs a b :
eq_view (PAbs a) (PAbs b)
| V_AbsNeu a b :
~~ isabs b ->
eq_view (PAbs a) b
| V_NeuAbs a b :
~~ isabs a ->
eq_view a (PAbs b)
| V_VarVar i j :
eq_view (VarPTm i) (VarPTm j)
| V_PairPair a0 b0 a1 b1 :
eq_view (PPair a0 b0) (PPair a1 b1)
| V_PairNeu a0 b0 u :
~~ ispair u ->
eq_view (PPair a0 b0) u
| V_NeuPair u a1 b1 :
~~ ispair u ->
eq_view u (PPair a1 b1)
| V_ZeroZero :
eq_view PZero PZero
| V_SucSuc a b :
eq_view (PSuc a) (PSuc b)
| V_AppApp u0 b0 u1 b1 :
eq_view (PApp u0 b0) (PApp u1 b1)
| V_ProjProj p0 u0 p1 u1 :
eq_view (PProj p0 u0) (PProj p1 u1)
| V_IndInd P0 u0 b0 c0 P1 u1 b1 c1 :
eq_view (PInd P0 u0 b0 c0) (PInd P1 u1 b1 c1)
| V_NatNat :
eq_view PNat PNat
| V_BindBind p0 A0 B0 p1 A1 B1 :
eq_view (PBind p0 A0 B0) (PBind p1 A1 B1)
| V_UnivUniv i j :
eq_view (PUniv i) (PUniv j)
| V_Others a b :
eq_view a b.
Equations tm_to_eq_view (a b : PTm) : eq_view a b :=
tm_to_eq_view (PAbs a) (PAbs b) := V_AbsAbs a b;
tm_to_eq_view (PAbs a) b := V_AbsNeu a b _;
tm_to_eq_view a (PAbs b) := V_NeuAbs a b _;
tm_to_eq_view (VarPTm i) (VarPTm j) := V_VarVar i j;
tm_to_eq_view (PPair a0 b0) (PPair a1 b1) := V_PairPair a0 b0 a1 b1;
tm_to_eq_view (PPair a0 b0) u := V_PairNeu a0 b0 u _;
tm_to_eq_view u (PPair a1 b1) := V_NeuPair u a1 b1 _;
tm_to_eq_view PZero PZero := V_ZeroZero;
tm_to_eq_view (PSuc a) (PSuc b) := V_SucSuc a b;
tm_to_eq_view (PApp a0 b0) (PApp a1 b1) := V_AppApp a0 b0 a1 b1;
tm_to_eq_view (PProj p0 b0) (PProj p1 b1) := V_ProjProj p0 b0 p1 b1;
tm_to_eq_view (PInd P0 u0 b0 c0) (PInd P1 u1 b1 c1) := V_IndInd P0 u0 b0 c0 P1 u1 b1 c1;
tm_to_eq_view PNat PNat := V_NatNat;
tm_to_eq_view (PUniv i) (PUniv j) := V_UnivUniv i j;
tm_to_eq_view (PBind p0 A0 B0) (PBind p1 A1 B1) := V_BindBind p0 A0 B0 p1 A1 B1;
tm_to_eq_view a b := V_Others a b.
Inductive algo_dom : PTm -> PTm -> Prop :=
| A_AbsAbs a b :
algo_dom a b ->
algo_dom_r a b ->
(* --------------------- *)
algo_dom (PAbs a) (PAbs b)
| A_AbsNeu a u :
ishne u ->
algo_dom a (PApp (ren_PTm shift u) (VarPTm var_zero)) ->
algo_dom_r a (PApp (ren_PTm shift u) (VarPTm var_zero)) ->
(* --------------------- *)
algo_dom (PAbs a) u
| A_NeuAbs a u :
ishne u ->
algo_dom (PApp (ren_PTm shift u) (VarPTm var_zero)) a ->
algo_dom_r (PApp (ren_PTm shift u) (VarPTm var_zero)) a ->
(* --------------------- *)
algo_dom u (PAbs a)
| A_PairPair a0 a1 b0 b1 :
algo_dom a0 a1 ->
algo_dom b0 b1 ->
algo_dom_r a0 a1 ->
algo_dom_r b0 b1 ->
(* ---------------------------- *)
algo_dom (PPair a0 b0) (PPair a1 b1)
| A_PairNeu a0 a1 u :
ishne u ->
algo_dom a0 (PProj PL u) ->
algo_dom a1 (PProj PR u) ->
algo_dom_r a0 (PProj PL u) ->
algo_dom_r a1 (PProj PR u) ->
(* ----------------------- *)
algo_dom (PPair a0 a1) u
| A_NeuPair a0 a1 u :
ishne u ->
algo_dom (PProj PL u) a0 ->
algo_dom (PProj PR u) a1 ->
algo_dom_r (PProj PL u) a0 ->
algo_dom_r (PProj PR u) a1 ->
(* ----------------------- *)
algo_dom u (PPair a0 a1)
| A_ZeroZero :
algo_dom PZero PZero
| A_SucSuc a0 a1 :
algo_dom_r a0 a1 ->
algo_dom (PSuc a0) (PSuc a1)
| A_UnivCong i j :
(* -------------------------- *)
algo_dom (PUniv i) (PUniv j)
| A_BindCong p0 p1 A0 A1 B0 B1 :
algo_dom A0 A1 ->
algo_dom B0 B1 ->
algo_dom_r A0 A1 ->
algo_dom_r B0 B1 ->
(* ---------------------------- *)
algo_dom (PBind p0 A0 B0) (PBind p1 A1 B1)
| A_NatCong :
algo_dom PNat PNat
| A_VarCong i j :
(* -------------------------- *)
algo_dom (VarPTm i) (VarPTm j)
@ -68,78 +231,199 @@ Inductive algo_dom {n} : PTm n -> PTm n -> Prop :=
ishne u0 ->
ishne u1 ->
algo_dom u0 u1 ->
algo_dom a0 a1 ->
algo_dom_r a0 a1 ->
(* ------------------------- *)
algo_dom (PApp u0 a0) (PApp u1 a1)
| A_IndCong P0 P1 u0 u1 b0 b1 c0 c1 :
ishne u0 ->
ishne u1 ->
algo_dom_r P0 P1 ->
algo_dom u0 u1 ->
algo_dom_r b0 b1 ->
algo_dom_r c0 c1 ->
algo_dom (PInd P0 u0 b0 c0) (PInd P1 u1 b1 c1)
with algo_dom_r : PTm -> PTm -> Prop :=
| A_NfNf a b :
algo_dom a b ->
algo_dom_r a b
| A_HRedL a a' b :
HRed.R a a' ->
algo_dom a' b ->
algo_dom_r a' b ->
(* ----------------------- *)
algo_dom a b
algo_dom_r a b
| A_HRedR a b b' :
ishne a \/ ishf a ->
HRed.R b b' ->
algo_dom a b' ->
algo_dom_r a b' ->
(* ----------------------- *)
algo_dom a b.
algo_dom_r a b.
Definition fin_eq {n} (i j : fin n) : bool.
Lemma algo_dom_hf_hne (a b : PTm) :
algo_dom a b ->
(ishf a \/ ishne a) /\ (ishf b \/ ishne b).
Proof.
induction n.
- by exfalso.
- refine (match i , j with
| None, None => true
| Some i, Some j => IHn i j
| _, _ => false
end).
Defined.
induction 1 =>//=; hauto lq:on.
Qed.
Lemma fin_eq_dec {n} (i j : fin n) :
Bool.reflect (i = j) (fin_eq i j).
Lemma hf_no_hred (a b : PTm) :
ishf a ->
HRed.R a b ->
False.
Proof. hauto l:on inv:HRed.R. Qed.
Lemma hne_no_hred (a b : PTm) :
ishne a ->
HRed.R a b ->
False.
Proof. elim : a b => //=; hauto l:on inv:HRed.R. Qed.
Derive Signature for algo_dom algo_dom_r.
Fixpoint hred (a : PTm) : option (PTm) :=
match a with
| VarPTm i => None
| PAbs a => None
| PApp (PAbs a) b => Some (subst_PTm (scons b VarPTm) a)
| PApp a b =>
match hred a with
| Some a => Some (PApp a b)
| None => None
end
| PPair a b => None
| PProj p (PPair a b) => if p is PL then Some a else Some b
| PProj p a =>
match hred a with
| Some a => Some (PProj p a)
| None => None
end
| PUniv i => None
| PBind p A B => None
| PBot => None
| PNat => None
| PZero => None
| PSuc a => None
| PInd P PZero b c => Some b
| PInd P (PSuc a) b c =>
Some (subst_PTm (scons (PInd P a b c) (scons a VarPTm)) c)
| PInd P a b c =>
match hred a with
| Some a => Some (PInd P a b c)
| None => None
end
end.
Lemma hred_complete (a b : PTm) :
HRed.R a b -> hred a = Some b.
Proof.
revert i j. induction n.
- destruct i.
- destruct i; destruct j.
+ specialize (IHn f f0).
inversion IHn; subst.
simpl. rewrite -H.
apply ReflectT.
reflexivity.
simpl. rewrite -H.
apply ReflectF.
injection. tauto.
+ by apply ReflectF.
+ by apply ReflectF.
+ by apply ReflectT.
Defined.
induction 1; hauto lq:on rew:off inv:HRed.R b:on.
Qed.
Lemma hred_sound (a b : PTm):
hred a = Some b -> HRed.R a b.
Proof.
elim : a b; hauto q:on dep:on ctrs:HRed.R.
Qed.
Equations check_equal {n} (a b : PTm n) (h : algo_dom a b) :
Lemma hred_deter (a b0 b1 : PTm) :
HRed.R a b0 -> HRed.R a b1 -> b0 = b1.
Proof.
move /hred_complete => + /hred_complete. congruence.
Qed.
Ltac check_equal_triv :=
intros;subst;
lazymatch goal with
(* | [h : algo_dom (VarPTm _) (PAbs _) |- _] => idtac *)
| [h : algo_dom _ _ |- _] => try (inversion h; by subst)
| _ => idtac
end.
Ltac solve_check_equal :=
try solve [intros *;
match goal with
| [|- _ = _] => sauto
| _ => idtac
end].
Equations check_equal (a b : PTm) (h : algo_dom a b) :
bool by struct h :=
check_equal a b h with (@idP (ishne a || ishf a)) := {
| Bool.ReflectT _ _ => _
| Bool.ReflectF _ _ => _
}.
check_equal a b h with tm_to_eq_view a b :=
check_equal _ _ h (V_VarVar i j) := nat_eqdec i j;
check_equal _ _ h (V_AbsAbs a b) := check_equal_r a b ltac:(check_equal_triv);
check_equal _ _ h (V_AbsNeu a b h') := check_equal_r a (PApp (ren_PTm shift b) (VarPTm var_zero)) ltac:(check_equal_triv);
check_equal _ _ h (V_NeuAbs a b _) := check_equal_r (PApp (ren_PTm shift a) (VarPTm var_zero)) b ltac:(check_equal_triv);
check_equal _ _ h (V_PairPair a0 b0 a1 b1) :=
check_equal_r a0 a1 ltac:(check_equal_triv) && check_equal_r b0 b1 ltac:(check_equal_triv);
check_equal _ _ h (V_PairNeu a0 b0 u _) :=
check_equal_r a0 (PProj PL u) ltac:(check_equal_triv) && check_equal_r b0 (PProj PR u) ltac:(check_equal_triv);
check_equal _ _ h (V_NeuPair u a1 b1 _) :=
check_equal_r (PProj PL u) a1 ltac:(check_equal_triv) && check_equal_r (PProj PR u) b1 ltac:(check_equal_triv);
check_equal _ _ h V_NatNat := true;
check_equal _ _ h V_ZeroZero := true;
check_equal _ _ h (V_SucSuc a b) := check_equal_r a b ltac:(check_equal_triv);
check_equal _ _ h (V_ProjProj p0 a p1 b) :=
PTag_eqdec p0 p1 && check_equal a b ltac:(check_equal_triv);
check_equal _ _ h (V_AppApp a0 b0 a1 b1) :=
check_equal a0 a1 ltac:(check_equal_triv) && check_equal_r b0 b1 ltac:(check_equal_triv);
check_equal _ _ h (V_IndInd P0 u0 b0 c0 P1 u1 b1 c1) :=
check_equal_r P0 P1 ltac:(check_equal_triv) &&
check_equal u0 u1 ltac:(check_equal_triv) &&
check_equal_r b0 b1 ltac:(check_equal_triv) &&
check_equal_r c0 c1 ltac:(check_equal_triv);
check_equal _ _ h (V_UnivUniv i j) := Nat.eqb i j;
check_equal _ _ h (V_BindBind p0 A0 B0 p1 A1 B1) :=
BTag_eqdec p0 p1 && check_equal_r A0 A1 ltac:(check_equal_triv) && check_equal_r B0 B1 ltac:(check_equal_triv);
check_equal _ _ _ _ := false
(* check_equal a b h := false; *)
with check_equal_r (a b : PTm) (h0 : algo_dom_r a b) :
bool by struct h0 :=
check_equal_r a b h with inspect (hred a) :=
check_equal_r a b h (exist _ (Some a') k) := check_equal_r a' b _;
check_equal_r a b h (exist _ None k) with inspect (hred b) :=
| (exist _ None l) => tm_nonconf a b && check_equal a b _;
| (exist _ (Some b') l) => check_equal_r a b' _.
(* check_equal (VarPTm i) (VarPTm j) h := fin_eq i j; *)
(* check_equal (PAbs a) (PAbs b) h := check_equal a b _; *)
(* check_equal (PPair a0 b0) (PPair a1 b1) h := *)
(* check_equal a0 b0 _ && check_equal a1 b1 _; *)
(* check_equal (PUniv i) (PUniv j) _ := _; *)
Next Obligation.
simpl.
intros ih.
Admitted.
intros.
destruct h.
exfalso. apply algo_dom_hf_hne in H.
apply hred_sound in k.
destruct H as [[|] _].
eauto using hf_no_hred.
eauto using hne_no_hred.
apply hred_sound in k.
assert ( a'0 = a')by eauto using hred_deter. subst.
apply h.
exfalso.
apply hred_sound in k.
destruct H as [|].
eauto using hne_no_hred.
eauto using hf_no_hred.
Defined.
Search (Bool.reflect (is_true _) _).
Check idP.
Next Obligation.
simpl. intros.
inversion h; subst =>//=.
move {h}. hauto lq:on use:algo_dom_hf_hne, hf_no_hred, hne_no_hred, hred_sound.
apply False_ind. hauto l:on use:hred_complete.
assert (b' = b'0) by eauto using hred_deter, hred_sound.
subst.
assumption.
Defined.
Definition metric {n} k (a b : PTm n) :=
exists i j va vb, nsteps LoRed.R i a va /\ nsteps LoRed.R j b vb /\
nf va /\ nf vb /\ size_PTm va + size_PTm vb + i + j <= k.
Next Obligation.
intros.
inversion h; subst => //=.
exfalso. hauto l:on use:hred_complete.
exfalso. hauto l:on use:hred_complete.
Defined.
Search (nat -> nat -> bool).
Next Obligation.
qauto inv:algo_dom, algo_dom_r.
Defined.
(* Do not step back from here or otherwise equations will cause an error *)