Library iris.bi.algebra

From iris.algebra Require Import cmra view auth agree csum list excl gmap.
From iris.algebra.lib Require Import excl_auth gmap_view dfrac_agree.
From iris.bi Require Export sbi_unfold derived_laws.
From iris.prelude Require Import options.
Local Set Default Proof Using "Type*".

Section algebra.
  Context `{!Sbi PROP}.

  Notation "P ⊢ Q" := (bi_entails (PROP:=PROP) P Q).
  Notation "P ⊣⊢ Q" := (equiv (A:=PROP) P%I Q%I).
  Notation "⊢ Q" := (bi_emp_valid (PROP:=PROP) Q).

  Lemma ucmra_unit_validI {A : ucmra} : (ε : A).
  Proof. sbi_unfold. apply ucmra_unit_validN. Qed.
  Lemma cmra_validI_op_r {A : cmra} (x y : A) : (x y) y.
  Proof. sbi_unfoldn. apply cmra_validN_op_r. Qed.
  Lemma cmra_validI_op_l {A : cmra} (x y : A) : (x y) x.
  Proof. sbi_unfoldn. apply cmra_validN_op_l. Qed.
  Lemma cmra_later_opI `{!CmraTotal A} (x y1 y2 : A) :
     ( x x y1 y2) z1 z2, x z1 z2 (z1 y1) (z2 y2).
  Proof.
    sbi_unfold⇒ -[|n].
    - intros _. x, (core x). by rewrite cmra_core_r.
    - intros [??].
      destruct (cmra_extend n x y1 y2) as (z1 & z2 & ? & ? & ?); [done..|].
       z1, z2. auto using equiv_dist.
  Qed.
  Lemma cmra_morphism_validI {A B : cmra} (f : A B) `{!CmraMorphism f} x :
     x (f x).
  Proof. sbi_unfoldn. by apply cmra_morphism_validN. Qed.

  Lemma prod_validI {A B : cmra} (x : A × B) : x ⊣⊢ x.1 x.2.
  Proof. by sbi_unfold. Qed.
  Lemma prod_includedI {A B : cmra} (x y : A × B) :
    x y ⊣⊢ x.1 y.1 x.2 y.2.
  Proof. sbi_unfoldn. apply prod_includedN. Qed.

  Lemma option_validI {A : cmra} (mx : option A) :
     mx ⊣⊢ match mx with Some x x | NoneTrue end.
  Proof. sbi_unfoldn. by destruct mx. Qed.
  Lemma option_includedI {A : cmra} (mx my : option A) :
    mx my ⊣⊢ match mx, my with
               | Some x, Some y(x y) (x y)
               | None, _True
               | Some x, NoneFalse
               end.
  Proof.
    sbi_unfoldn. destruct mx, my; rewrite ?option_includedN; naive_solver.
  Qed.
  Lemma option_included_totalI `{!CmraTotal A} (mx my : option A) :
    mx my ⊣⊢ match mx, my with
               | Some x, Some yx y
               | None, _True
               | Some x, NoneFalse
               end.
  Proof.
    sbi_unfoldn; destruct mx, my;
      rewrite ?Some_includedN_total ?option_includedN; naive_solver.
  Qed.
  Lemma Some_included_totalI `{!CmraTotal A} (x y : A) :
    Some x Some y ⊣⊢ x y.
  Proof. by rewrite option_included_totalI. Qed.

  Lemma discrete_fun_validI {A} {B : A ucmra} (g : discrete_fun B) :
     g ⊣⊢ i, g i.
  Proof. by sbi_unfold. Qed.

  Lemma f_homom_includedI {A B : cmra} (x y : A) (f : A B) `{!NonExpansive f} :
    
    ( c, f x f c f (x c))
    (x y f x f y).
  Proof. intros Hf. sbi_unfoldn. intros [z ->]. rewrite -Hf. by eexists. Qed.

  Lemma id_freeI_r {A : cmra} (x y : A) :
    IdFree x ⊢@{PROP} x -∗ (x y) x -∗ False.
  Proof. intros. sbi_unfold. eauto using id_freeN_r. Qed.
  Lemma id_freeI_l {A : cmra} (x y : A) :
    IdFree x x -∗ (y x) x -∗ False.
  Proof. intros. sbi_unfold. eauto using id_freeN_l. Qed.

  Section gmap_ofe.
    Context `{Countable K} {A : ofe}.
    Implicit Types m : gmap K A.
    Implicit Types i : K.

    Lemma gmap_equivI m1 m2 : m1 m2 ⊣⊢ i, m1 !! i m2 !! i.
    Proof. by sbi_unfold. Qed.

    Lemma gmap_union_equiv_eqI m m1 m2 :
      m m1 m2 ⊣⊢ m1' m2', m = m1' m2' m1' m1 m2' m2.
    Proof. sbi_unfoldn. apply gmap_union_dist_eq. Qed.
  End gmap_ofe.

  Section gmap_cmra.
    Context `{Countable K} {A : cmra}.
    Implicit Types m : gmap K A.

    Lemma gmap_validI m : m ⊣⊢ i, (m !! i).
    Proof. by sbi_unfold. Qed.
    Lemma singleton_validI i x : ({[ i := x ]} : gmap K A) ⊣⊢ x.
    Proof. sbi_unfoldn. apply singleton_validN. Qed.
  End gmap_cmra.

  Section list_ofe.
    Context {A : ofe}.
    Implicit Types l : list A.

    Lemma list_equivI l1 l2 : l1 l2 ⊣⊢ i, l1 !! i l2 !! i.
    Proof. sbi_unfold. intros n. apply list_dist_lookup. Qed.
  End list_ofe.

  Section excl.
    Context {A : ofe}.
    Implicit Types x : excl A.

    Lemma excl_equivI x y :
      x y ⊣⊢ match x, y with
                          | Excl a, Excl ba b
                          | ExclInvalid, ExclInvalidTrue
                          | _, _False
                          end.
    Proof.
      sbi_unfold; split; [by destruct 1|destruct x, y; by repeat constructor].
    Qed.

    Lemma excl_validI x :
       x ⊣⊢ if x is ExclInvalid then False else True.
    Proof. by sbi_unfold. Qed.

    Lemma excl_includedI (x y : excl A) :
      x y ⊣⊢ y = ExclInvalid .
    Proof. sbi_unfoldn; apply excl_includedN. Qed.
  End excl.

  Section agree.
    Context {A : ofe}.
    Implicit Types a b : A.
    Implicit Types x y : agree A.

    Lemma agree_equivI a b : to_agree a to_agree b ⊣⊢ (a b).
    Proof. sbi_unfoldn. apply: inj_iff. Qed.
    Lemma agree_op_invI x y : (x y) x y.
    Proof. sbi_unfoldn. apply agree_op_invN. Qed.

    Lemma to_agree_validI a : to_agree a.
    Proof. by sbi_unfold. Qed.
    Lemma to_agree_op_validI a b : (to_agree a to_agree b) ⊣⊢ a b.
    Proof. sbi_unfold. apply to_agree_op_validN. Qed.

    Lemma to_agree_uninjI x : x a, to_agree a x.
    Proof. sbi_unfoldn. exact: to_agree_uninjN. Qed.

Derived lemma: If two x y : agree O compose to some to_agree a, they are internally equal, and also equal to the to_agree a.
Empirically, x y to_agree a appears often when agreement comes up in CMRA validity terms, especially when views are involved. The desired simplification x y y to_agree a is also not straightforward to derive, so we have a special lemma to handle this common case.
    Lemma agree_op_equiv_to_agreeI x y a :
      x y to_agree a x y y to_agree a.
    Proof.
      assert (x y to_agree a x y) as Hxy_equiv.
      { rewrite -(agree_op_invI x y) internal_eq_sym.
        apply: (internal_eq_rewrite' _ _ (λ o, o)%I); [solve_proper|done|].
        rewrite -(bi.absorbing_absorbingly ( _)).
        rewrite -to_agree_validI bi.absorbingly_emp_True. apply bi.True_intro. }
      apply bi.and_intro; first done.
      rewrite -{1}(idemp bi_and (_ _)%I) {1}Hxy_equiv. apply bi.impl_elim_l'.
      apply: (internal_eq_rewrite' _ _
        (λ y', x y' to_agree a y' to_agree a)%I); [solve_proper|done|].
      rewrite agree_idemp. apply bi.impl_refl.
    Qed.

    Lemma agree_includedI (x y : agree A) : x y ⊣⊢ y x y.
    Proof. sbi_unfoldn. apply agree_includedN. Qed.

    Lemma to_agree_includedI a b : to_agree a to_agree b ⊣⊢ a b.
    Proof. sbi_unfoldn. apply: to_agree_includedN. Qed.
  End agree.

  Section csum_ofe.
    Context {A B : ofe}.
    Implicit Types a : A.
    Implicit Types b : B.

    Lemma csum_equivI (x y : csum A B) :
      x y ⊣⊢ match x, y with
                          | Cinl a, Cinl a'a a'
                          | Cinr b, Cinr b'b b'
                          | CsumInvalid, CsumInvalidTrue
                          | _, _False
                          end.
    Proof.
      sbi_unfold; split; [by destruct 1|destruct x, y; by repeat constructor].
    Qed.
  End csum_ofe.

  Section csum_cmra.
    Context {A B : cmra}.
    Implicit Types a : A.
    Implicit Types b : B.

    Lemma csum_validI (x : csum A B) :
       x ⊣⊢ match x with
                        | Cinl a a
                        | Cinr b b
                        | CsumInvalidFalse
                        end.
    Proof. by sbi_unfold. Qed.

    Lemma csum_includedI (sx sy : csum A B) :
      sx sy ⊣⊢ match sx, sy with
                 | Cinl x, Cinl yx y
                 | Cinr x, Cinr yx y
                 | _, CsumInvalidTrue
                 | _, _False
                 end.
    Proof.
      sbi_unfoldn; destruct sx, sy; rewrite ?csum_includedN; naive_solver.
    Qed.
  End csum_cmra.

  Section view.
    Context {A B} (rel : view_rel A B).
    Implicit Types a : A.
    Implicit Types ag : option (frac × agree A).
    Implicit Types b : B.
    Implicit Types x y : view rel.

    Lemma view_both_dfrac_validI_1 (relI : siProp) dq a b :
      ( n, rel n a b siProp_holds relI n)
       (V{dq} a V b : view rel) dq <si_pure> relI.
    Proof.
      intros. sbi_unfoldn. rewrite view_both_dfrac_validN. naive_solver.
    Qed.
    Lemma view_both_dfrac_validI_2 (relI : siProp) dq a b :
      ( n, siProp_holds relI n rel n a b)
      dq <si_pure> relI (V{dq} a V b : view rel).
    Proof.
      intros. sbi_unfoldn. rewrite view_both_dfrac_validN. naive_solver.
    Qed.
    Lemma view_both_dfrac_validI (relI : siProp) dq a b :
      ( n, rel n a b siProp_holds relI n)
       (V{dq} a V b : view rel) ⊣⊢ dq <si_pure> relI.
    Proof.
      intros. apply (anti_symm _);
        [apply view_both_dfrac_validI_1|apply view_both_dfrac_validI_2]; naive_solver.
    Qed.

    Lemma view_both_validI_1 (relI : siProp) a b :
      ( n, rel n a b siProp_holds relI n)
       (V a V b : view rel) <si_pure> relI.
    Proof. intros. by rewrite view_both_dfrac_validI_1 // bi.and_elim_r. Qed.
    Lemma view_both_validI_2 (relI : siProp) a b :
      ( n, siProp_holds relI n rel n a b)
      <si_pure> relI (V a V b : view rel).
    Proof.
      intros. rewrite -view_both_dfrac_validI_2 //.
      apply bi.and_intro; [|done]. by apply bi.pure_intro.
    Qed.
    Lemma view_both_validI (relI : siProp) a b :
      ( n, rel n a b siProp_holds relI n)
       (V a V b : view rel) ⊣⊢ <si_pure> relI.
    Proof.
      intros. apply (anti_symm _);
        [apply view_both_validI_1|apply view_both_validI_2]; naive_solver.
    Qed.

    Lemma view_auth_dfrac_validI (relI : siProp) dq a :
      ( n, siProp_holds relI n rel n a ε)
       (V{dq} a : view rel) ⊣⊢ dq <si_pure> relI.
    Proof.
      intros. rewrite -(right_id ε op (V{dq} a)). by apply view_both_dfrac_validI.
    Qed.
    Lemma view_auth_validI (relI : siProp) a :
      ( n, siProp_holds relI n rel n a ε)
       (V a : view rel) ⊣⊢ <si_pure> relI.
    Proof. intros. rewrite -(right_id ε op (V a)). by apply view_both_validI. Qed.

    Lemma view_frag_validI (relI : siProp) b :
      ( n, siProp_holds relI n a, rel n a b)
       (V b : view rel) ⊣⊢ <si_pure> relI.
    Proof. intros Hrel. sbi_unfoldn. by rewrite Hrel. Qed.
  End view.

  Section auth.
    Context {A : ucmra}.
    Implicit Types a b : A.
    Implicit Types x y : auth A.

    Lemma auth_auth_dfrac_validI dq a : ({dq} a) ⊣⊢ dq a.
    Proof. sbi_unfoldn. apply auth_auth_dfrac_validN. Qed.
    Lemma auth_auth_validI a : ( a) ⊣⊢ a.
    Proof. sbi_unfoldn. apply auth_auth_validN. Qed.
    Lemma auth_auth_dfrac_op_validI dq1 dq2 a1 a2 :
       ({dq1} a1 {dq2} a2) ⊣⊢ (dq1 dq2) (a1 a2) a1.
    Proof. sbi_unfoldn. apply auth_auth_dfrac_op_validN. Qed.

    Lemma auth_frag_validI a : ( a) ⊣⊢ a.
    Proof. sbi_unfoldn. apply auth_frag_validN. Qed.

    Lemma auth_both_dfrac_validI dq a b :
       ({dq} a b) ⊣⊢ dq ( c, a b c) a.
    Proof. sbi_unfoldn. apply auth_both_dfrac_validN. Qed.
    Lemma auth_both_validI a b :
       ( a b) ⊣⊢ ( c, a b c) a.
    Proof. sbi_unfoldn. apply auth_both_validN. Qed.
  End auth.

  Section excl_auth.
    Context {A : ofe}.
    Implicit Types a b : A.

    Lemma excl_auth_agreeI a b : (E a E b) (a b).
    Proof. sbi_unfoldn. apply excl_auth_agreeN. Qed.
  End excl_auth.

  Section dfrac_agree.
    Context {A : ofe}.
    Implicit Types a b : A.

    Lemma dfrac_agree_validI dq a : (to_dfrac_agree dq a) ⊣⊢ dq.
    Proof. sbi_unfoldn. rewrite /to_dfrac_agree pair_validN. naive_solver. Qed.

    Lemma dfrac_agree_validI_2 dq1 dq2 a b :
       (to_dfrac_agree dq1 a to_dfrac_agree dq2 b) ⊣⊢ (dq1 dq2) (a b).
    Proof.
      rewrite prod_validI /= internal_cmra_valid_discrete to_agree_op_validI //.
    Qed.

    Lemma frac_agree_validI q a : (to_frac_agree q a) ⊣⊢ (q 1)%Qp.
    Proof.
      rewrite dfrac_agree_validI dfrac_valid_own //.
    Qed.

    Lemma frac_agree_validI_2 q1 q2 a b :
       (to_frac_agree q1 a to_frac_agree q2 b) ⊣⊢ (q1 + q2 1)%Qp (a b).
    Proof.
      rewrite dfrac_agree_validI_2 dfrac_valid_own //.
    Qed.
  End dfrac_agree.

  Section gmap_view.
    Context `{Countable K} {V : cmra}.
    Implicit Types (m : gmap K V) (k : K) (dq : dfrac) (v : V).

    Lemma gmap_view_both_dfrac_validI dp m k dq v :
       (gmap_view_auth dp m gmap_view_frag k dq v) ⊣⊢
       v' dq', dp m !! k = Some v' (dq', v')
                Some (dq, v) Some (dq', v').
    Proof. sbi_unfoldn. apply: gmap_view_both_dfrac_validN. Qed.
    Lemma gmap_view_both_validI m dp k v :
       (gmap_view_auth dp m gmap_view_frag k (DfracOwn 1) v) ⊣⊢
       dp v m !! k Some v.
    Proof. sbi_unfoldn. apply gmap_view_both_validN. Qed.
    Lemma gmap_view_both_validI_total `{!CmraTotal V} dp m k dq v :
       (gmap_view_auth dp m gmap_view_frag k dq v)
       v', dp dq m !! k = Some v' v' v v'.
    Proof. sbi_unfoldn. apply: gmap_view_both_dfrac_validN_total. Qed.

    Lemma gmap_view_frag_op_validI k dq1 dq2 v1 v2 :
       (gmap_view_frag k dq1 v1 gmap_view_frag k dq2 v2) ⊣⊢
       (dq1 dq2) (v1 v2).
    Proof. sbi_unfoldn. apply gmap_view_frag_op_validN. Qed.
  End gmap_view.
End algebra.