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import OAI.InformationTheory.SecretKey.Construction
namespace OAI
noncomputable section
namespace UnrestrictedQuantum
open Matrix MeasureTheory
open scoped ComplexOrder MatrixOrder
universe v3096_0 v3096_1 v3096_2 v3096_3 v3096_4
variable {A : Type v3096_0} {B : Type v3096_1} {C : Type v3096_2} [inst3096_0 : AddCommGroup A] [inst3096_1 : Module ℂ A] [inst3096_2 : One A]
[inst3096_3 : AddCommGroup B] [inst3096_4 : Module ℂ B] [inst3096_5 : One B]
[inst3096_6 : AddCommGroup C] [inst3096_7 : Module ℂ C] [inst3096_8 : One C]
{ι : Type v3096_3} {κ : Type v3096_4} [inst3096_9 : Fintype ι] [inst3096_10 : Fintype κ] [inst3096_11 : DecidableEq ι] [inst3096_12 : DecidableEq κ]
def filterFunctional (K : Matrix κ ι ℂ) (S : ReferenceFunctional A ι) :
ReferenceFunctional A κ where
toFun x := K * S x * Kᴴ
map_add' x y := by rw [map_add, Matrix.mul_add, Matrix.add_mul]
map_smul' z x := by simp only [map_smul, Matrix.mul_smul, Matrix.smul_mul,
RingHom.id_apply]
omit inst3096_2 inst3096_5 inst3096_10 inst3096_11 inst3096_12 in
theorem filter_precompose [One A] [One B] [Fintype κ] [DecidableEq ι] [DecidableEq κ] (K : Matrix κ ι ℂ) (S : ReferenceFunctional A ι)
(L : B →ₗ[ℂ] A) :
filterFunctional K (S.comp L) = (filterFunctional K S).comp L := rfl
omit inst3096_2 inst3096_5 inst3096_8 inst3096_10 inst3096_11 inst3096_12 in
theorem filter_precompose_two [One A] [One B] [One C] [Fintype κ] [DecidableEq ι] [DecidableEq κ] (K : Matrix κ ι ℂ) (S : ReferenceFunctional A ι)
(L : B →ₗ[ℂ] A) (M : C →ₗ[ℂ] B) :
filterFunctional K ((S.comp L).comp M) =
((filterFunctional K S).comp L).comp M := rfl
omit inst3096_2 inst3096_11 inst3096_12 in
lemma filter_positive [One A] [DecidableEq ι] [DecidableEq κ] [LE A] (K : Matrix κ ι ℂ)
{S : ReferenceFunctional A ι} (hS : PositiveFunctional S) :
PositiveFunctional (filterFunctional K S) := by
intro x hx
exact (hS x hx).mul_mul_conjTranspose_same K
universe v3147_0
variable {O : Type v3147_0} [inst3147_0 : MeasurableSpace O] [inst3147_1 : LE A] [inst3147_2 : LE B]
(J : ObservableInstrument O A B) (S : ReferenceFunctional A ι)
namespace InstrumentRun
variable (r : InstrumentRun J S)
omit inst3096_11 in
theorem event_reference [DecidableEq ι] (E : Set O) (hE : MeasurableSet E) :
(fun i j => ∫ o in E, r.posterior o 1 i j ∂r.law) =
S (J.operation E 1) := by
ext i j
exact r.update E hE 1 i j
omit inst3096_10 inst3096_11 inst3096_12 in
theorem filter_event [Fintype κ] [DecidableEq ι] [DecidableEq κ] (K : Matrix κ ι ℂ) (E : Set O) (hE : MeasurableSet E) :
(fun i j => ∫ o in E, filterFunctional K (r.posterior o) 1 i j ∂r.law) =
filterFunctional K S (J.operation E 1) := by
ext i j
simp only [filterFunctional, LinearMap.coe_mk, AddHom.coe_mk,
Matrix.mul_apply, Finset.sum_mul]
rw [integral_finsetSum _ (fun k _ =>
integrable_finsetSum _ (fun l _ =>
(((r.integrable 1 l k).const_mul (K i l)).mul_const (Kᴴ k j)).integrableOn))]
simp_rw [integral_finsetSum _ (fun l _ =>
(((r.integrable 1 l _).const_mul (K i l)).mul_const _).integrableOn),
integral_mul_const, integral_const_mul, r.update E hE]
end InstrumentRun
end UnrestrictedQuantum
open MeasureTheory ProbabilityTheory Set Function unitInterval
open scoped ENNReal
namespace ZeroKey
universe v3238_0 v3238_1 v3238_2
theorem sample_instrument_update {S : Type v3238_0} {O : Type v3238_1} {Z : Type v3238_2} [MeasurableSpace S]
[MeasurableSpace O] [StandardBorelSpace O] [Nonempty O] [MeasurableSpace Z]
(κ : Kernel S O) [IsMarkovKernel κ]
(update : S × O → Z) (hu : Measurable update) :
∃ f : S → I → O, Measurable (uncurry f) ∧
∀ (μ : Measure S) [IsFiniteMeasure μ],
(μ.prod (volume : Measure I)).map (fun p => update (p.1, f p.1 p.2)) =
(μ ⊗ₘ κ).map update := by
obtain ⟨f,hf,_,hLaw⟩ := sample_instrument_kernel κ
change Measurable (fun p : S × I => f p.1 p.2) at hf
refine ⟨f,hf,?_⟩
intro μ hμ
rw [← hLaw μ, Measure.map_map hu (measurable_fst.prodMk hf)]
rfl
lemma uniform_prefix_fresh_independent (n : ℕ) :
IndepFun (fun u : UniformTape => fun i : Fin n => u i) (fun u => u n) uniformTapeLaw := by
have h := iIndepFun_infinitePi (P := fun _ : ℕ => (volume : Measure I))
(X := fun _ x => x) (fun _ => measurable_id)
have hd : Disjoint (Finset.range n) {n} := by simp
have hh := h.indepFun_finset (Finset.range n) {n} hd (fun i => measurable_pi_apply i)
have hh' := hh.comp
(show Measurable (fun x : (i : Finset.range n) → I => fun j : Fin n =>
x ⟨j,Finset.mem_range.mpr j.isLt⟩) from by fun_prop)
(show Measurable (fun x : (i : ({n} : Finset ℕ)) → I => x ⟨n,by simp⟩) from by fun_prop)
exact hh'
lemma uniform_tape_eval (n : ℕ) : uniformTapeLaw.map (fun u => u n) = volume :=
Measure.infinitePi_map_eval _ _
universe v3280_0
structure CausalSampler (O : Type v3280_0) [MeasurableSpace O] where
step : (n : ℕ) → (Fin n → O) × I → O
measurable_step : ∀ n, Measurable (step n)
namespace CausalSampler
universe v3285_0
variable {O : Type v3285_0} [inst3285_0 : MeasurableSpace O] (f : CausalSampler O)
def finiteHistory : (n : ℕ) → (Fin n → I) → (Fin n → O)
| 0, _ => Fin.elim0
| n+1, u => Fin.snoc (finiteHistory n (fun i => u i.castSucc))
(f.step n (finiteHistory n (fun i => u i.castSucc), u (Fin.last n)))
lemma measurable_finiteHistory : ∀ n, Measurable (f.finiteHistory n) := by
intro n
induction n with
| zero => exact Measurable.of_eval (fun i => Fin.elim0 i)
| succ n ih =>
have hr : Measurable (fun u : Fin (n+1) → I => fun i : Fin n => u i.castSucc) := by fun_prop
apply Measurable.of_eval
intro i
refine Fin.lastCases ?_ (fun j => ?_) i
· simpa only [finiteHistory, Fin.snoc_last,Function.comp_def] using
(f.measurable_step n).comp ((ih.comp hr).prodMk (measurable_pi_apply (Fin.last n)))
· simpa only [finiteHistory, Fin.snoc_castSucc,Function.comp_def] using (ih.comp hr).eval (a := j)
def history (n : ℕ) (u : UniformTape) : Fin n → O :=
f.finiteHistory n (fun i => u i)
lemma measurable_prefix (n : ℕ) : Measurable (f.history n) :=
(f.measurable_finiteHistory n).comp (by fun_prop)
lemma prefix_succ (n : ℕ) (u : UniformTape) :
f.history (n+1) u = Fin.snoc (f.history n u) (f.step n (f.history n u,u n)) := rfl
lemma prefix_fresh_independent (n : ℕ) :
IndepFun (f.history n) (fun u => u n) uniformTapeLaw :=
(uniform_prefix_fresh_independent n).comp (f.measurable_finiteHistory n) measurable_id
lemma prefix_fresh_law (n : ℕ) :
uniformTapeLaw.map (fun u => (f.history n u,u n)) =
(uniformTapeLaw.map (f.history n)).prod volume := by
rw [(f.prefix_fresh_independent n).map_prod_eq_prod_map_map
(f.measurable_prefix n).aemeasurable (measurable_pi_apply n).aemeasurable,
uniform_tape_eval]
theorem prefix_law_succ (κ : (n : ℕ) → Kernel (Fin n → O) O)
[∀ n, IsMarkovKernel (κ n)]
(hlaw : ∀ n s, volume.map (fun u => f.step n (s,u)) = κ n s)
(n : ℕ) :
uniformTapeLaw.map (f.history (n+1)) =
((uniformTapeLaw.map (f.history n)) ⊗ₘ κ n).map (fun p : (Fin n → O) × O => Fin.snoc (α := fun _ : Fin (n+1) => O) p.1 p.2) := by
have hfresh := f.prefix_fresh_law n
have hsample : ((uniformTapeLaw.map (f.history n)).prod (volume : Measure I)).map
(fun p => (p.1, f.step n p)) = (uniformTapeLaw.map (f.history n)) ⊗ₘ κ n := by
ext B hB
rw [Measure.map_apply (measurable_fst.prodMk (f.measurable_step n)) hB,
Measure.prod_apply (hB.preimage (measurable_fst.prodMk (f.measurable_step n))),
Measure.compProd_apply hB]
congr 1
funext s
have hm : Measurable (fun u : I => f.step n (s,u)) := by
simpa only [Function.comp_def, id_eq] using
((f.measurable_step n).comp ((measurable_const (a := s)).prodMk measurable_id))
rw [← hlaw n s, Measure.map_apply hm (measurable_prodMk_left hB)]
rfl
have hs : Measurable (fun p : (Fin n → O) × O => Fin.snoc (α := fun _ : Fin (n+1) => O) p.1 p.2) := by
apply Measurable.of_eval
intro i
refine Fin.lastCases ?_ (fun j => ?_) i
· simpa only [Fin.snoc_last] using measurable_snd
· simpa only [Fin.snoc_castSucc, Function.comp_def] using (measurable_pi_apply j).comp measurable_fst
rw [← hsample, ← hfresh,
Measure.map_map (measurable_fst.prodMk (f.measurable_step n))
((f.measurable_prefix n).prodMk (measurable_pi_apply n)),
Measure.map_map hs ((measurable_fst.prodMk (f.measurable_step n)).comp
((f.measurable_prefix n).prodMk (measurable_pi_apply n)))]
rfl
def record (u : UniformTape) (n : ℕ) : O := f.step n (f.history n u,u n)
lemma measurable_record : Measurable f.record :=
Measurable.of_eval (fun n =>
(f.measurable_step n).comp ((f.measurable_prefix n).prodMk (measurable_pi_apply n)))
lemma prefix_eq_record (n : ℕ) (u : UniformTape) (i : Fin n) :
f.history n u i = f.record u i := by
induction n with
| zero => exact Fin.elim0 i
| succ n ih =>
rw [f.prefix_succ]
refine Fin.lastCases ?_ (fun j => ?_) i
· simp only [Fin.snoc_last,record, Fin.val_last]
· simpa only [Fin.snoc_castSucc, Fin.val_castSucc] using ih j
theorem finite_law_unique (κ : (n : ℕ) → Kernel (Fin n → O) O)
[∀ n, IsMarkovKernel (κ n)]
(hlaw : ∀ n s, volume.map (fun u => f.step n (s,u)) = κ n s)
(P : Measure (ℕ → O)) [IsProbabilityMeasure P]
(hP : ∀ n, P.map (fun x => fun i : Fin (n+1) => x i) =
((P.map (fun x => fun i : Fin n => x i)) ⊗ₘ κ n).map
(fun p : (Fin n → O) × O => Fin.snoc (α := fun _ : Fin (n+1) => O) p.1 p.2)) :
∀ n, P.map (fun x => fun i : Fin n => x i) = uniformTapeLaw.map (f.history n) := by
intro n
induction n with
| zero =>
have ht : (fun x : ℕ → O => fun i : Fin 0 => x i) = fun _ => Fin.elim0 := by
funext x i
exact Fin.elim0 i
rw [ht]
change P.map (fun _ : ℕ → O => Fin.elim0) =
uniformTapeLaw.map (fun _ : UniformTape => Fin.elim0)
simp
| succ n ih => rw [hP n, ih, f.prefix_law_succ κ hlaw]
theorem record_law_unique (κ : (n : ℕ) → Kernel (Fin n → O) O)
[∀ n, IsMarkovKernel (κ n)]
(hlaw : ∀ n s, volume.map (fun u => f.step n (s,u)) = κ n s)
(P : Measure (ℕ → O)) [IsProbabilityMeasure P]
(hP : ∀ n, P.map (fun x => fun i : Fin (n+1) => x i) =
((P.map (fun x => fun i : Fin n => x i)) ⊗ₘ κ n).map
(fun p : (Fin n → O) × O => Fin.snoc (α := fun _ : Fin (n+1) => O) p.1 p.2)) :
P = uniformTapeLaw.map f.record := by
let Q := uniformTapeLaw.map f.record
have hQ : IsProbabilityMeasure Q := inferInstance
apply IsProjectiveLimit.unique (P := fun J : Finset ℕ => Q.map J.restrict) ?_
(show IsProjectiveLimit Q (fun J : Finset ℕ => Q.map J.restrict) from fun _ => rfl)
intro J
let n := J.sup id + 1
let index : J → Fin n := fun j => ⟨j.1,Nat.lt_succ_of_le (Finset.le_sup (f := id) j.2)⟩
let cut : (Fin n → O) → (J → O) := fun x j => x (index j)
have hc : Measurable cut := by fun_prop
have h := congrArg (fun ν : Measure (Fin n → O) => ν.map cut)
(f.finite_law_unique κ hlaw P hP n)
rw [Measure.map_map hc (by fun_prop), Measure.map_map hc (f.measurable_prefix n)] at h
change P.map J.restrict = (uniformTapeLaw.map f.record).map J.restrict
rw [Measure.map_map (Finset.measurable_restrict J) f.measurable_record]
have heL : cut ∘ (fun x : ℕ → O => fun i : Fin n => x i) = J.restrict := rfl
have heR : cut ∘ f.history n = J.restrict ∘ f.record := by
funext u j
exact f.prefix_eq_record n u (index j)
rwa [heL,heR] at h
end CausalSampler
universe v3434_0
theorem exists_causal_sampler {O : Type v3434_0} [MeasurableSpace O]
[StandardBorelSpace O] [Nonempty O]
(κ : (n : ℕ) → Kernel (Fin n → O) O) [∀ n, IsMarkovKernel (κ n)] :
∃ f : CausalSampler O, ∀ n s, volume.map (fun u => f.step n (s,u)) = κ n s := by
have h (n : ℕ) := sample_instrument_kernel (κ n)
choose sample hmeas hlaw hrest using h
exact ⟨⟨fun n p => sample n p.1 p.2, hmeas⟩, hlaw⟩
end ZeroKey
open MeasureTheory ProbabilityTheory Filter
open scoped ENNReal
namespace ZeroKey
section
universe v3447_0
variable {Ω : Type v3447_0} {mΩ : MeasurableSpace Ω} [inst3447_0 : StandardBorelSpace Ω]
{μ : Measure Ω} [inst3447_1 : IsFiniteMeasure μ]
lemma condIndep_public_prefixes (ℱ : Filtration ℕ mΩ)
(A B : MeasurableSpace Ω) (hA : A ≤ mΩ) (hB : B ≤ mΩ)
(hinitial : CondIndep (ℱ 0) A B (ℱ.le 0) μ)
(hlocal : ∀ n, ℱ (n+1) ≤ A ⊔ ℱ n ∨ ℱ (n+1) ≤ B ⊔ ℱ n) :
∀ n, CondIndep (ℱ n) A B (ℱ.le n) μ := by
intro n
induction n with
| zero => exact hinitial
| succ n ih =>
rcases hlocal n with h | h
· exact condIndep_local_message (ℱ.le n) hA hB (ℱ.mono (Nat.le_succ n)) h ih
· exact (condIndep_local_message (ℱ.le n) hB hA (ℱ.mono (Nat.le_succ n)) h ih.symm).symm
end
open MeasureTheory ProbabilityTheory
universe v3676_0
variable {Ω : Type v3676_0} {mΩ : MeasurableSpace Ω} [inst3676_0 : StandardBorelSpace Ω]
{μ : Measure Ω} [inst3676_1 : IsFiniteMeasure μ]
theorem independent_tapes_given_full_transcript (ℱ : Filtration ℕ mΩ)
(A B : MeasurableSpace Ω) (hA : A ≤ mΩ) (hB : B ≤ mΩ)
(hinitial : CondIndep (ℱ 0) A B (ℱ.le 0) μ)
(hlocal : ∀ n, ℱ (n+1) ≤ A ⊔ ℱ n ∨ ℱ (n+1) ≤ B ⊔ ℱ n) :
CondIndep (⨆ n, ℱ n) (A ⊔ ⨆ n, ℱ n) (B ⊔ ⨆ n, ℱ n)
(iSup_le fun n => ℱ.le n) μ := by
have h := condIndep_full_transcript ℱ A B hA hB
(condIndep_public_prefixes ℱ A B hA hB hinitial hlocal)
have hC := iSup_le fun n => ℱ.le n
have h1 := (condIndep_join_public_right hC hB hA h.symm).symm
exact condIndep_join_public_right hC (sup_le hA hC) hB h1
end ZeroKey
open MeasureTheory ProbabilityTheory Function Set
namespace ZeroKey
namespace LocalTapeProgram
universe v3724_0 v3724_1 v3724_2
variable {U : Type v3724_0} {V : Type v3724_1} {M : Type v3724_2} [inst3724_0 : MeasurableSpace U] [inst3724_1 : MeasurableSpace V] [inst3724_2 : MeasurableSpace M]
(p : LocalTapeProgram U V M)
def message (n : ℕ) (ω : U × V) : M :=
if p.alice n then p.sendA n (ω.1,p.publicPrefix n ω) else p.sendB n (ω.2,p.publicPrefix n ω)
lemma prefix_succ (n : ℕ) (ω : U × V) :
p.publicPrefix (n+1) ω = Fin.snoc (p.publicPrefix n ω) (p.message n ω) := rfl
lemma measurable_prefix : ∀ n, Measurable (p.publicPrefix n) := by
intro n
induction n with
| zero => exact Measurable.of_eval (fun i => Fin.elim0 i)
| succ n ih =>
apply Measurable.of_eval
intro i
refine Fin.lastCases ?_ (fun j => ?_) i
· simp only [publicPrefix, Fin.snoc_last]
split
· exact (p.measA n).comp (measurable_fst.prodMk ih)
· exact (p.measB n).comp (measurable_snd.prodMk ih)
· simpa only [publicPrefix, Fin.snoc_castSucc] using ih.eval (a := j)
lemma measurable_message (n : ℕ) : Measurable (p.message n) := by
unfold message
split
· exact (p.measA n).comp (measurable_fst.prodMk (p.measurable_prefix n))
· exact (p.measB n).comp (measurable_snd.prodMk (p.measurable_prefix n))
@[instance_reducible]
def field (n : ℕ) : MeasurableSpace (U × V) :=
MeasurableSpace.comap (p.publicPrefix n) inferInstance
lemma field_le (n : ℕ) : p.field n ≤ (inferInstance : MeasurableSpace (U × V)) := (p.measurable_prefix n).comap_le
lemma field_mono : Monotone p.field := by
apply monotone_nat_of_le_succ
intro n
have h : @Measurable (U × V) (Fin n → M) (p.field (n+1)) _ (p.publicPrefix n) := by
let : MeasurableSpace (U × V) := p.field (n+1)
apply Measurable.of_eval
intro i
have hh := (@Measurable.of_comap_le (U × V) (Fin (n+1) → M)
(p.field (n+1)) _ (p.publicPrefix (n+1)) le_rfl).eval (a := i.castSucc)
simpa only [publicPrefix, Fin.snoc_castSucc] using hh
exact h.comap_le
def filtration : Filtration ℕ (inferInstance : MeasurableSpace (U × V)) where
seq := p.field
mono' := p.field_mono
le' := p.field_le
lemma field_zero : p.field 0 = ⊥ := by
exact MeasurableSpace.comap_const Fin.elim0
lemma field_local (n : ℕ) :
p.field (n+1) ≤ MeasurableSpace.comap Prod.fst ‹MeasurableSpace U› ⊔ p.field n ∨
p.field (n+1) ≤ MeasurableSpace.comap Prod.snd ‹MeasurableSpace V› ⊔ p.field n := by
have hp {C : MeasurableSpace (U × V)} (hC : p.field n ≤ C) :
@Measurable (U × V) (Fin n → M) C _ (p.publicPrefix n) := Measurable.of_comap_le hC
have hf {C : MeasurableSpace (U × V)}
(hC : MeasurableSpace.comap Prod.fst ‹MeasurableSpace U› ≤ C) :
@Measurable (U × V) U C _ Prod.fst := Measurable.of_comap_le hC
have hg {C : MeasurableSpace (U × V)}
(hC : MeasurableSpace.comap Prod.snd ‹MeasurableSpace V› ≤ C) :
@Measurable (U × V) V C _ Prod.snd := Measurable.of_comap_le hC
cases ha : p.alice n
· right
let : MeasurableSpace (U × V) := MeasurableSpace.comap Prod.snd ‹MeasurableSpace V› ⊔ p.field n
apply Measurable.comap_le
apply Measurable.of_eval
intro i
refine Fin.lastCases ?_ (fun j => ?_) i
· simpa only [publicPrefix, Fin.snoc_last, ha, Bool.false_eq_true, ↓reduceIte, Function.comp_def] using
(p.measB n).comp ((hg le_sup_left).prodMk (hp le_sup_right))
· simpa only [publicPrefix, Fin.snoc_castSucc] using (hp le_sup_right).eval (a := j)
· left
let : MeasurableSpace (U × V) := MeasurableSpace.comap Prod.fst ‹MeasurableSpace U› ⊔ p.field n
apply Measurable.comap_le
apply Measurable.of_eval
intro i
refine Fin.lastCases ?_ (fun j => ?_) i
· simpa only [publicPrefix, Fin.snoc_last, ha, ↓reduceIte, Function.comp_def] using
(p.measA n).comp ((hf le_sup_left).prodMk (hp le_sup_right))
· simpa only [publicPrefix, Fin.snoc_castSucc] using (hp le_sup_right).eval (a := j)
theorem tapes_conditionally_independent [StandardBorelSpace U] [StandardBorelSpace V]
(μ : Measure U) (ν : Measure V) [IsProbabilityMeasure μ] [IsProbabilityMeasure ν] :
CondIndep (⨆ n, p.field n)
(MeasurableSpace.comap Prod.fst ‹MeasurableSpace U› ⊔ ⨆ n, p.field n)
(MeasurableSpace.comap Prod.snd ‹MeasurableSpace V› ⊔ ⨆ n, p.field n)
(iSup_le p.field_le) (μ.prod ν) := by
apply independent_tapes_given_full_transcript p.filtration _ _
measurable_fst.comap_le measurable_snd.comap_le
· change CondIndep (p.field 0) _ _ _ _
have h0 := indep_condIndep_bot measurable_fst.comap_le measurable_snd.comap_le
(P := μ.prod ν) (indepFun_prod (μ := μ) (ν := ν) measurable_id measurable_id)
simpa only [p.field_zero] using h0
· exact p.field_local
def record (ω : U × V) (n : ℕ) : M := p.message n ω
lemma measurable_record : Measurable p.record :=
Measurable.of_eval p.measurable_message
lemma prefix_eq_record (n : ℕ) (ω : U × V) (i : Fin n) :
p.publicPrefix n ω i = p.record ω i := by
induction n with
| zero => exact Fin.elim0 i
| succ n ih =>
refine Fin.lastCases ?_ (fun j => ?_) i
· simp only [publicPrefix, Fin.snoc_last, record, message, Fin.val_last]
· simpa only [publicPrefix, Fin.snoc_castSucc, Fin.val_castSucc] using ih j
lemma full_record_field :
MeasurableSpace.comap p.record inferInstance = ⨆ n, p.field n := by
apply le_antisymm
· let : MeasurableSpace (U × V) := ⨆ n, p.field n
apply Measurable.comap_le
apply Measurable.of_eval
intro n
have h : @Measurable (U × V) (Fin (n+1) → M) (⨆ n, p.field n) _
(p.publicPrefix (n+1)) := Measurable.of_comap_le (le_iSup p.field (n+1))
simpa only [publicPrefix, Fin.snoc_last, record, message] using h.eval (a := Fin.last n)
· apply iSup_le
intro n
let : MeasurableSpace (U × V) := MeasurableSpace.comap p.record inferInstance
apply Measurable.comap_le
apply Measurable.of_eval
intro i
simp_rw [prefix_eq_record]
exact (Measurable.of_comap_le (f := p.record) le_rfl).eval
universe v3866_0 v3866_1
theorem final_records_conditionally_independent
[StandardBorelSpace U] [StandardBorelSpace V]
(μ : Measure U) (ν : Measure V) [IsProbabilityMeasure μ] [IsProbabilityMeasure ν]
{A : Type v3866_0} {B : Type v3866_1} [MeasurableSpace A] [MeasurableSpace B]
(readA : U × (ℕ → M) → A) (readB : V × (ℕ → M) → B)
(ha : Measurable readA) (hb : Measurable readB) :
CondIndepFun (MeasurableSpace.comap p.record inferInstance)
p.measurable_record.comap_le
(fun ω => readA (ω.1,p.record ω))
(fun ω => readB (ω.2,p.record ω)) (μ.prod ν) := by
have h := p.tapes_conditionally_independent μ ν
rw [condIndepFun_iff_condIndep]
have hA : MeasurableSpace.comap (fun ω => readA (ω.1,p.record ω)) inferInstance ≤
MeasurableSpace.comap Prod.fst ‹MeasurableSpace U› ⊔ ⨆ n, p.field n := by
apply Measurable.comap_le
exact ha.comp ((Measurable.of_comap_le le_sup_left).prodMk
(Measurable.of_comap_le (p.full_record_field ▸ le_sup_right)))
have hB : MeasurableSpace.comap (fun ω => readB (ω.2,p.record ω)) inferInstance ≤
MeasurableSpace.comap Prod.snd ‹MeasurableSpace V› ⊔ ⨆ n, p.field n := by
apply Measurable.comap_le
exact hb.comp ((Measurable.of_comap_le le_sup_left).prodMk
(Measurable.of_comap_le (p.full_record_field ▸ le_sup_right)))
have h' := condIndep_of_condIndep_of_le_right
(condIndep_of_condIndep_of_le_left h hA) hB
simpa only [p.full_record_field] using h'
end LocalTapeProgram
end ZeroKey
open MeasureTheory ProbabilityTheory Function Set unitInterval
namespace ZeroKey
theorem selected_tapes_law (alice : ℕ → Bool) :
(uniformTapeLaw.prod uniformTapeLaw).map
(fun uv : UniformTape × UniformTape => fun n => if alice n then uv.1 n else uv.2 n) =
uniformTapeLaw := by
let ν : Measure ((Fin 2 × ℕ) → I) :=
Measure.infinitePi (fun _ => (volume : Measure I))
let split : ((Fin 2 × ℕ) → I) → UniformTape × UniformTape :=
fun u => (fun n => u (0,n), fun n => u (1,n))
have hs : Measurable split := by fun_prop
have hsplit : ν.map split = uniformTapeLaw.prod uniformTapeLaw := by
have hc := Measure.infinitePi_map_curry (fun (_ : Fin 2) (_ : ℕ) => (volume : Measure I))
change ν.map (MeasurableEquiv.curry (Fin 2) ℕ I) =
Measure.infinitePi (fun _ : Fin 2 => uniformTapeLaw) at hc
rw [Measure.infinitePi_eq_pi (fun _ : Fin 2 => uniformTapeLaw)] at hc
have h := congrArg (fun P : Measure (Fin 2 → UniformTape) =>
P.map MeasurableEquiv.finTwoArrow) hc
rw [Measure.map_map (MeasurableEquiv.measurable _) (MeasurableEquiv.measurable _),
(measurePreserving_finTwoArrow uniformTapeLaw).map_eq] at h
exact h
let chooseTape : UniformTape × UniformTape → UniformTape :=
fun uv n => if alice n then uv.1 n else uv.2 n
have hm : Measurable chooseTape := by
apply Measurable.of_eval
intro n
dsimp [chooseTape]
split <;> fun_prop
rw [← hsplit, Measure.map_map hm hs]
let index : ℕ → Fin 2 × ℕ := fun n => (if alice n then 0 else 1,n)
have hi : Injective index := by intro a b hab; exact congrArg Prod.snd hab
have h := Measure.map_infinitePi_infinitePi_of_inj
(P := fun _ : Fin 2 × ℕ => (volume : Measure I)) hi
have he : chooseTape ∘ split = fun u n => u (index n) := by
funext u n
dsimp [chooseTape,split,index]
split <;> rfl
rw [he]
exact h
namespace LocalOutcomeSampler
universe v3955_0 v3955_1
variable {O : Type v3955_0} {M : Type v3955_1} [inst3955_0 : MeasurableSpace O] [inst3955_1 : MeasurableSpace M]
(p : LocalOutcomeSampler O M)
lemma measurable_privatePrefix (a : Bool) : ∀ n, Measurable (p.privatePrefix a n) := by
intro n
induction n with
| zero => exact Measurable.of_eval (fun i => Fin.elim0 i)
| succ n ih =>
have hr : Measurable (fun pair : UniformTape × (Fin (n+1) → M) =>
(pair.1,fun i : Fin n => pair.2 i.castSucc)) := by fun_prop
have hv : Measurable (fun pair : UniformTape × (Fin (n+1) → M) =>
fun i : Fin n => pair.2 i.castSucc) := by fun_prop
apply Measurable.of_eval
intro i
refine Fin.lastCases ?_ (fun j => ?_) i
· simp only [privatePrefix,Fin.snoc_last]
split
· apply measurable_inl.comp
split
· exact (p.sampleA_meas n).comp (((ih.comp hr).prodMk hv).prodMk
((measurable_pi_apply n).comp measurable_fst))
· exact (p.sampleB_meas n).comp (((ih.comp hr).prodMk hv).prodMk
((measurable_pi_apply n).comp measurable_fst))
· exact measurable_const
· simpa only [privatePrefix,Fin.snoc_castSucc,Function.comp_def] using
(ih.comp hr).eval (a := j)
def tapeProgram : LocalTapeProgram UniformTape UniformTape M where
alice := p.alice
sendA n pair := p.sendA n ((p.privatePrefix true n pair,pair.2),
p.sampleA n ((p.privatePrefix true n pair,pair.2),pair.1 n))
sendB n pair := p.sendB n ((p.privatePrefix false n pair,pair.2),
p.sampleB n ((p.privatePrefix false n pair,pair.2),pair.1 n))
measA n := (p.sendA_meas n).comp
(((p.measurable_privatePrefix true n).prodMk measurable_snd).prodMk
((p.sampleA_meas n).comp (((p.measurable_privatePrefix true n).prodMk measurable_snd).prodMk
((measurable_pi_apply n).comp measurable_fst))))
measB n := (p.sendB_meas n).comp
(((p.measurable_privatePrefix false n).prodMk measurable_snd).prodMk
((p.sampleB_meas n).comp (((p.measurable_privatePrefix false n).prodMk measurable_snd).prodMk
((measurable_pi_apply n).comp measurable_fst))))
def privateRecord (a : Bool) (pair : UniformTape × (ℕ → M)) (n : ℕ) : (O ⊕ Unit) :=
if p.alice n = a then
let past := fun i : Fin n => pair.2 i
let privatePast := p.privatePrefix a n (pair.1,past)
Sum.inl (if a then p.sampleA n ((privatePast,past),pair.1 n)
else p.sampleB n ((privatePast,past),pair.1 n))
else Sum.inr ()
lemma measurable_privateRecord (a : Bool) : Measurable (p.privateRecord a) := by
apply Measurable.of_eval
intro n
have hp : Measurable (fun pair : UniformTape × (ℕ → M) => fun i : Fin n => pair.2 i) := by fun_prop
have hl := (p.measurable_privatePrefix a n).comp (measurable_fst.prodMk hp)
simp only [privateRecord]
split
· apply measurable_inl.comp
split
· exact (p.sampleA_meas n).comp ((hl.prodMk hp).prodMk
((measurable_pi_apply n).comp measurable_fst))
· exact (p.sampleB_meas n).comp ((hl.prodMk hp).prodMk
((measurable_pi_apply n).comp measurable_fst))
· exact measurable_const
universe v4032_0 v4032_1
theorem final_records_independent {A : Type v4032_0} {B : Type v4032_1} [MeasurableSpace A] [MeasurableSpace B]
(readA : (ℕ → (O ⊕ Unit)) × (ℕ → M) → A)
(readB : (ℕ → (O ⊕ Unit)) × (ℕ → M) → B)
(ha : Measurable readA) (hb : Measurable readB) :
CondIndepFun (MeasurableSpace.comap p.tapeProgram.record inferInstance)
p.tapeProgram.measurable_record.comap_le
(fun uv => readA (p.privateRecord true (uv.1,p.tapeProgram.record uv),p.tapeProgram.record uv))
(fun uv => readB (p.privateRecord false (uv.2,p.tapeProgram.record uv),p.tapeProgram.record uv))
(uniformTapeLaw.prod uniformTapeLaw) := by
exact p.tapeProgram.final_records_conditionally_independent uniformTapeLaw uniformTapeLaw
(fun pair => readA (p.privateRecord true pair,pair.2))
(fun pair => readB (p.privateRecord false pair,pair.2))
(ha.comp ((p.measurable_privateRecord true).prodMk measurable_snd))
(hb.comp ((p.measurable_privateRecord false).prodMk measurable_snd))
lemma measurable_extractPrivate (a : Bool) (n : ℕ) :
Measurable (p.extractPrivate a n) := by
apply Measurable.of_eval
intro i
unfold extractPrivate
split
· exact measurable_inl.comp (measurable_pi_apply i)
· exact measurable_const
lemma extractPrivate_snoc (a : Bool) (n : ℕ) (x : Fin n → O) (z : O) :
p.extractPrivate a (n+1) (Fin.snoc (α := fun _ => O) x z) =
Fin.snoc (p.extractPrivate a n x) (if p.alice n = a then Sum.inl z else Sum.inr ()) := by
funext i
refine Fin.lastCases ?_ (fun j => ?_) i
· simp only [extractPrivate,Fin.snoc_last,Fin.val_last]
· simp only [extractPrivate,Fin.snoc_castSucc,Fin.val_castSucc]
lemma measurable_publicFrom : ∀ n, Measurable (p.publicFrom n) := by
intro n
induction n with
| zero => exact Measurable.of_eval (fun i => Fin.elim0 i)
| succ n ih =>
have hr : Measurable (fun x : Fin (n+1) → O => fun i : Fin n => x i.castSucc) := by fun_prop
apply Measurable.of_eval
intro i
refine Fin.lastCases ?_ (fun j => ?_) i
· simp only [publicFrom,Fin.snoc_last]
split
· exact (p.sendA_meas n).comp ((((p.measurable_extractPrivate true n).comp hr).prodMk
(ih.comp hr)).prodMk (measurable_pi_apply (Fin.last n)))
· exact (p.sendB_meas n).comp ((((p.measurable_extractPrivate false n).comp hr).prodMk
(ih.comp hr)).prodMk (measurable_pi_apply (Fin.last n)))
· simpa only [publicFrom,Fin.snoc_castSucc,Function.comp_def] using (ih.comp hr).eval (a := j)
lemma publicFrom_snoc (n : ℕ) (x : Fin n → O) (z : O) :
p.publicFrom (n+1) (Fin.snoc (α := fun _ => O) x z) =
Fin.snoc (p.publicFrom n x) (if p.alice n then
p.sendA n ((p.extractPrivate true n x,p.publicFrom n x),z) else
p.sendB n ((p.extractPrivate false n x,p.publicFrom n x),z)) := by
simp only [publicFrom,Fin.snoc_castSucc,Fin.snoc_last]
lemma privatePrefix_snoc (a : Bool) (n : ℕ) (u : UniformTape) (h : Fin n → M) (z : M) :
p.privatePrefix a (n+1) (u,Fin.snoc (α := fun _ => M) h z) =
Fin.snoc (p.privatePrefix a n (u,h)) (if p.alice n = a then Sum.inl
(if a then p.sampleA n ((p.privatePrefix a n (u,h),h),u n)
else p.sampleB n ((p.privatePrefix a n (u,h),h),u n)) else Sum.inr ()) := by
simp only [privatePrefix,Fin.snoc_castSucc]
def causal : CausalSampler O where
step n pair := if p.alice n then
p.sampleA n ((p.extractPrivate true n pair.1,p.publicFrom n pair.1),pair.2) else
p.sampleB n ((p.extractPrivate false n pair.1,p.publicFrom n pair.1),pair.2)
measurable_step n := by
split
· exact (p.sampleA_meas n).comp ((((p.measurable_extractPrivate true n).comp measurable_fst).prodMk
((p.measurable_publicFrom n).comp measurable_fst)).prodMk measurable_snd)
· exact (p.sampleB_meas n).comp ((((p.measurable_extractPrivate false n).comp measurable_fst).prodMk
((p.measurable_publicFrom n).comp measurable_fst)).prodMk measurable_snd)
def selectedTape (uv : UniformTape × UniformTape) (n : ℕ) : I :=
if p.alice n then uv.1 n else uv.2 n
lemma measurable_selectedTape : Measurable p.selectedTape := by
apply Measurable.of_eval
intro n
unfold selectedTape
split <;> fun_prop
theorem replay_matches (n : ℕ) (uv : UniformTape × UniformTape) :
p.publicFrom n (p.causal.history n (p.selectedTape uv)) = p.tapeProgram.publicPrefix n uv ∧
∀ a : Bool, p.extractPrivate a n (p.causal.history n (p.selectedTape uv)) =
p.privatePrefix a n ((if a then uv.1 else uv.2),p.tapeProgram.publicPrefix n uv) := by
induction n with
| zero =>
constructor
· rfl
· intro a; funext i; exact Fin.elim0 i
| succ n ih =>
have hs : p.causal.step n (p.causal.history n (p.selectedTape uv),p.selectedTape uv n) =
if p.alice n then
p.sampleA n ((p.privatePrefix true n (uv.1,p.tapeProgram.publicPrefix n uv),
p.tapeProgram.publicPrefix n uv),uv.1 n) else
p.sampleB n ((p.privatePrefix false n (uv.2,p.tapeProgram.publicPrefix n uv),
p.tapeProgram.publicPrefix n uv),uv.2 n) := by
change (if p.alice n then
p.sampleA n ((p.extractPrivate true n (p.causal.history n (p.selectedTape uv)),
p.publicFrom n (p.causal.history n (p.selectedTape uv))),p.selectedTape uv n)
else p.sampleB n ((p.extractPrivate false n (p.causal.history n (p.selectedTape uv)),
p.publicFrom n (p.causal.history n (p.selectedTape uv))),p.selectedTape uv n)) = _
rw [ih.1,ih.2 true,ih.2 false]
simp only [Bool.false_eq_true,↓reduceIte,selectedTape]
split <;> simp_all only []
rw [p.causal.prefix_succ,p.publicFrom_snoc,hs,ih.1,ih.2 true,ih.2 false]
simp only [Bool.false_eq_true,↓reduceIte]
constructor
· rw [p.tapeProgram.prefix_succ]
congr 1
unfold LocalTapeProgram.message tapeProgram
split <;> simp_all only [↓reduceIte]
· intro a
rw [p.extractPrivate_snoc,ih.2 a,p.tapeProgram.prefix_succ,p.privatePrefix_snoc]
congr 1
cases a <;> cases hrole : p.alice n <;>
simp only [Bool.false_eq_true,Bool.true_eq_false,↓reduceIte]
def outcomeRecord (uv : UniformTape × UniformTape) : ℕ → O :=
p.causal.record (p.selectedTape uv)
lemma measurable_outcomeRecord : Measurable p.outcomeRecord :=
p.causal.measurable_record.comp p.measurable_selectedTape
lemma outcomeRecord_law (κ : (n : ℕ) → Kernel (Fin n → O) O)
[∀ n, IsMarkovKernel (κ n)]
(hlaw : ∀ n s, volume.map (fun u => p.causal.step n (s,u)) = κ n s)
(P : Measure (ℕ → O)) [IsProbabilityMeasure P]
(hP : ∀ n, P.map (fun x => fun i : Fin (n+1) => x i) =
((P.map (fun x => fun i : Fin n => x i)) ⊗ₘ κ n).map
(fun pair : (Fin n → O) × O => Fin.snoc (α := fun _ : Fin (n+1) => O) pair.1 pair.2)) :
(uniformTapeLaw.prod uniformTapeLaw).map p.outcomeRecord = P := by
rw [p.causal.record_law_unique κ hlaw P hP]
change (uniformTapeLaw.prod uniformTapeLaw).map (p.causal.record ∘ p.selectedTape) = _
rw [← Measure.map_map p.causal.measurable_record p.measurable_selectedTape]
congr 1
exact selected_tapes_law p.alice
def publicRecord (x : ℕ → O) (n : ℕ) : M :=
p.publicFrom (n+1) (fun i => x i) (Fin.last n)
def localRecord (a : Bool) (x : ℕ → O) (n : ℕ) : O ⊕ Unit :=
if p.alice n = a then Sum.inl (x n) else Sum.inr ()
lemma measurable_publicRecord : Measurable p.publicRecord := by
apply Measurable.of_eval
intro n
exact ((p.measurable_publicFrom (n+1)).comp (by fun_prop)).eval (a := Fin.last n)
lemma measurable_localRecord (a : Bool) : Measurable (p.localRecord a) := by
apply Measurable.of_eval
intro n
unfold localRecord
split
· exact measurable_inl.comp (measurable_pi_apply n)
· exact measurable_const
lemma publicRecord_replay (uv : UniformTape × UniformTape) :
p.publicRecord (p.outcomeRecord uv) = p.tapeProgram.record uv := by
funext n
have h := congrFun (p.replay_matches (n+1) uv).1 (Fin.last n)
have he : (fun i : Fin (n+1) => p.outcomeRecord uv i) =
p.causal.history (n+1) (p.selectedTape uv) := by
funext i
exact (p.causal.prefix_eq_record (n+1) (p.selectedTape uv) i).symm
change p.publicFrom (n+1) (fun i => p.outcomeRecord uv i) (Fin.last n) = _
rw [he,h,p.tapeProgram.prefix_eq_record]
rfl
lemma localRecord_replay (a : Bool) (uv : UniformTape × UniformTape) :
p.localRecord a (p.outcomeRecord uv) =
p.privateRecord a ((if a then uv.1 else uv.2),p.tapeProgram.record uv) := by
funext n
have h := congrFun ((p.replay_matches (n+1) uv).2 a) (Fin.last n)
rw [p.causal.prefix_succ,p.extractPrivate_snoc,p.tapeProgram.prefix_succ,
p.privatePrefix_snoc] at h
simp only [Fin.snoc_last] at h
have he : p.tapeProgram.publicPrefix n uv = fun i : Fin n => p.tapeProgram.record uv i := by
funext i; exact p.tapeProgram.prefix_eq_record n uv i
rw [he] at h
exact h
universe v4239_0 v4239_1
theorem full_readout_law {A : Type v4239_0} {B : Type v4239_1} [MeasurableSpace A] [MeasurableSpace B]
(κ : (n : ℕ) → Kernel (Fin n → O) O) [∀ n, IsMarkovKernel (κ n)]
(hlaw : ∀ n s, volume.map (fun u => p.causal.step n (s,u)) = κ n s)
(P : Measure (ℕ → O)) [IsProbabilityMeasure P]
(hP : ∀ n, P.map (fun x => fun i : Fin (n+1) => x i) =
((P.map (fun x => fun i : Fin n => x i)) ⊗ₘ κ n).map
(fun pair : (Fin n → O) × O => Fin.snoc (α := fun _ : Fin (n+1) => O) pair.1 pair.2))
(readA : (ℕ → (O ⊕ Unit)) × (ℕ → M) → A)
(readB : (ℕ → (O ⊕ Unit)) × (ℕ → M) → B)
(ha : Measurable readA) (hb : Measurable readB) :
P.map (fun x => (p.publicRecord x,
readA (p.localRecord true x,p.publicRecord x),
readB (p.localRecord false x,p.publicRecord x))) =
(uniformTapeLaw.prod uniformTapeLaw).map (fun uv => (p.tapeProgram.record uv,
readA (p.privateRecord true (uv.1,p.tapeProgram.record uv),p.tapeProgram.record uv),
readB (p.privateRecord false (uv.2,p.tapeProgram.record uv),p.tapeProgram.record uv))) := by
rw [← p.outcomeRecord_law κ hlaw P hP]
have hm : Measurable (fun x => (p.publicRecord x,
readA (p.localRecord true x,p.publicRecord x),
readB (p.localRecord false x,p.publicRecord x))) := by
exact p.measurable_publicRecord.prodMk
((ha.comp ((p.measurable_localRecord true).prodMk p.measurable_publicRecord)).prodMk
(hb.comp ((p.measurable_localRecord false).prodMk p.measurable_publicRecord)))
rw [Measure.map_map hm p.measurable_outcomeRecord]
congr 1
funext uv
simp only [Function.comp_def,p.publicRecord_replay,p.localRecord_replay,
Bool.false_eq_true,↓reduceIte]
end LocalOutcomeSampler
end ZeroKey
end
end OAI