From 9fc48e669ef4da895081acbb66e3b4f781d28db9 Mon Sep 17 00:00:00 2001
From: Robbert Krebbers <mail@robbertkrebbers.nl>
Date: Tue, 2 Feb 2016 23:05:55 +0100
Subject: [PATCH] Indexed products as COFE and CMRA.

---
 modures/cmra.v | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 modures/cofe.v | 37 +++++++++++++++++++++++++++++++++++--
 2 files changed, 81 insertions(+), 2 deletions(-)

diff --git a/modures/cmra.v b/modures/cmra.v
index f4c49ee41..c5d385f67 100644
--- a/modures/cmra.v
+++ b/modures/cmra.v
@@ -527,3 +527,49 @@ Definition prodRA_map {A A' B B' : cmraT}
   CofeMor (prod_map f g : prodRA A B → prodRA A' B').
 Instance prodRA_map_ne {A A' B B'} n :
   Proper (dist n==> dist n==> dist n) (@prodRA_map A A' B B') := prodC_map_ne n.
+
+(** ** Indexed product *)
+Section iprod_cmra.
+  Context {A} {B : A → cmraT}.
+  Instance iprod_op : Op (iprod B) := λ f g x, f x ⋅ g x.
+  Instance iprod_unit : Unit (iprod B) := λ f x, unit (f x).
+  Instance iprod_validN : ValidN (iprod B) := λ n f, ∀ x, ✓{n} (f x).
+  Instance iprod_minus : Minus (iprod B) := λ f g x, f x ⩪ g x.
+  Lemma iprod_includedN_spec (f g : iprod B) n : f ≼{n} g ↔ ∀ x, f x ≼{n} g x.
+  Proof.
+    split.
+    * by intros [h Hh] x; exists (h x); rewrite /op /iprod_op (Hh x).
+    * intros Hh; exists (g ⩪ f)=> x; specialize (Hh x).
+      by rewrite /op /iprod_op /minus /iprod_minus cmra_op_minus.
+  Qed.
+  Definition iprod_cmra_mixin : CMRAMixin (iprod B).
+  Proof.
+    split.
+    * by intros n f1 f2 f3 Hf x; rewrite /op /iprod_op (Hf x).
+    * by intros n f1 f2 Hf x; rewrite /unit /iprod_unit (Hf x).
+    * by intros n f1 f2 Hf ? x; rewrite -(Hf x).
+    * by intros n f f' Hf g g' Hg i; rewrite /minus /iprod_minus (Hf i) (Hg i).
+    * by intros f x.
+    * intros n f Hf x; apply cmra_validN_S, Hf.
+    * by intros f1 f2 f3 x; rewrite /op /iprod_op associative.
+    * by intros f1 f2 x; rewrite /op /iprod_op commutative.
+    * by intros f x; rewrite /op /iprod_op /unit /iprod_unit cmra_unit_l.
+    * by intros f x; rewrite /unit /iprod_unit cmra_unit_idempotent.
+    * intros n f1 f2; rewrite !iprod_includedN_spec=> Hf x.
+      by rewrite /unit /iprod_unit; apply cmra_unit_preservingN, Hf.
+    * intros n f1 f2 Hf x; apply cmra_validN_op_l with (f2 x), Hf.
+    * intros n f1 f2; rewrite iprod_includedN_spec=> Hf x.
+      by rewrite /op /iprod_op /minus /iprod_minus cmra_op_minus; try apply Hf.
+  Qed.
+  Definition iprod_cmra_extend_mixin : CMRAExtendMixin (iprod B).
+  Proof.
+    intros n f f1 f2 Hf Hf12.
+    set (g x := cmra_extend_op n (f x) (f1 x) (f2 x) (Hf x) (Hf12 x)).
+    exists ((λ x, (proj1_sig (g x)).1), (λ x, (proj1_sig (g x)).2)).
+    split_ands; intros x; apply (proj2_sig (g x)).
+  Qed.
+  Canonical Structure iprodRA : cmraT :=
+    CMRAT iprod_cofe_mixin iprod_cmra_mixin iprod_cmra_extend_mixin.
+End iprod_cmra.
+
+Arguments iprodRA : clear implicits.
diff --git a/modures/cofe.v b/modures/cofe.v
index becd4395a..98fc986a4 100644
--- a/modures/cofe.v
+++ b/modures/cofe.v
@@ -195,8 +195,8 @@ Section cofe_mor.
   Definition cofe_mor_cofe_mixin : CofeMixin (cofeMor A B).
   Proof.
     split.
-    * intros X Y; split; [intros HXY n k; apply equiv_dist, HXY|].
-      intros HXY k; apply equiv_dist; intros n; apply HXY.
+    * intros f g; split; [intros Hfg n k; apply equiv_dist, Hfg|].
+      intros Hfg k; apply equiv_dist; intros n; apply Hfg.
     * intros n; split.
       + by intros f x.
       + by intros f g ? x.
@@ -367,3 +367,36 @@ Definition laterC_map {A B} (f : A -n> B) : laterC A -n> laterC B :=
   CofeMor (later_map f).
 Instance laterC_map_contractive (A B : cofeT) : Contractive (@laterC_map A B).
 Proof. intros n f g Hf n'; apply Hf. Qed.
+
+(** Indexed product *)
+(** Need to put this in a definition to make canonical structures to work. *)
+Definition iprod {A} (B : A → cofeT) := ∀ x, B x.
+
+Section iprod_cofe.
+  Context {A} {B : A → cofeT}.
+  Instance iprod_equiv : Equiv (iprod B) := λ f g, ∀ x, f x ≡ g x.
+  Instance iprod_dist : Dist (iprod B) := λ n f g, ∀ x, f x ={n}= g x.
+  Program Definition iprod_chain (c : chain (iprod B)) (x : A) : chain (B x) :=
+    {| chain_car n := c n x |}.
+  Next Obligation. by intros c x n i ?; apply (chain_cauchy c). Qed.
+  Program Instance iprod_compl : Compl (iprod B) := λ c x,
+    compl (iprod_chain c x).
+  Definition iprod_cofe_mixin : CofeMixin (iprod B).
+  Proof.
+    split.
+    * intros f g; split; [intros Hfg n k; apply equiv_dist, Hfg|].
+      intros Hfg k; apply equiv_dist; intros n; apply Hfg.
+    * intros n; split.
+      + by intros f x.
+      + by intros f g ? x.
+      + by intros f g h ?? x; transitivity (g x).
+    * intros n f g Hfg x; apply dist_S, Hfg.
+    * by intros f g x.
+    * intros c n x.
+      rewrite /compl /iprod_compl (conv_compl (iprod_chain c x) n).
+      apply (chain_cauchy c); lia.
+  Qed.
+  Canonical Structure iprodC : cofeT := CofeT iprod_cofe_mixin.
+End iprod_cofe.
+
+Arguments iprodC : clear implicits.
-- 
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