File size: 7,828 Bytes
2f887db
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
import OAI.Computability.PerfectCompleteness.Construction.HiddenBucketBias
import OAI.Computability.PerfectCompleteness.Sampling.PreliminarySampler
import OAI.Computability.PerfectCompleteness.Sampling.RationalFiniteLawLemmas
import OAI.Computability.PerfectCompleteness.Sampling.SourceChildKernelMarginalLemmas

namespace OAI

section

namespace PerfectCompleteness.SourceChildQuestionLaw

open RecursiveSpaces TreeSourceSpaces HierarchicalArrays SourceQuestionReconstruction
open UniqueGamesTheorem.Foundations.Games
open scoped Classical

noncomputable section

variable {branch : Nat → Nat} {n m t v : Nat}

def sourceLaw (m t : Nat) [NeZero m] (designated : Fin (branch n) → Slots branch n) :
    FiniteDistribution (SourceChildKernel.Sources (m := m) (t := t) designated) :=
  FiniteProduct.law (fun i => (SourceOddLists.tupleLaw m t).product
    (FiniteProduct.law (fun _ : {leaf : Slots branch n // leaf ≠ designated i} =>
      SourceOddLists.tupleLaw m t)))

def assembleEquiv (designated : Fin (branch n) → Slots branch n) :
    SourceChildKernel.Sources (m := m) (t := t) designated ≃
      (Slots branch (n + 1) → SourceTuple m t) where
  toFun sources leaf := CleanSourceRecord.assemble designated leaf.1
    (sources leaf.1).1 (sources leaf.1).2 leaf.2
  invFun tree i := (Equiv.piSplitAt (designated i) (fun _ : Slots branch n => SourceTuple m t))
    (fun leaf => tree (i, leaf))
  left_inv sources := by
    funext i
    exact (Equiv.piSplitAt (designated i) (fun _ : Slots branch n => SourceTuple m t)).apply_symm_apply
      (sources i)
  right_inv tree := by
    funext leaf
    exact congrFun
      ((Equiv.piSplitAt (designated leaf.1) (fun _ : Slots branch n => SourceTuple m t)).symm_apply_apply
        (fun s => tree (leaf.1, s))) leaf.2

theorem assemble_child_law (designated : Fin (branch n) → Slots branch n)
    (μ : FiniteDistribution (SourceTuple m t)) (i : Fin (branch n)) :
    (μ.product (FiniteProduct.law
      (fun _ : {leaf : Slots branch n // leaf ≠ designated i} => μ))).pushforward
        (fun source => CleanSourceRecord.assemble designated i source.1 source.2) =
      FiniteProduct.law (fun _ : Slots branch n => μ) := by
  let split := Equiv.piSplitAt (designated i) (fun _ : Slots branch n => SourceTuple m t)
  have hsplit : (FiniteProduct.law (fun _ : Slots branch n => μ)).pushforward split =
      μ.product (FiniteProduct.law
        (fun _ : {leaf : Slots branch n // leaf ≠ designated i} => μ)) :=
    SourceCoordinateSplit.coordinate_split_pushforward (fun _ : Slots branch n => μ) (designated i)
  change (μ.product (FiniteProduct.law
    (fun _ : {leaf : Slots branch n // leaf ≠ designated i} => μ))).pushforward split.symm = _
  rw [← hsplit, FiniteDistribution.pushforward_comp]
  simp only [Equiv.symm_apply_apply]
  exact UniqueGamesTheorem.Foundations.Games.FiniteDistribution.pushforward_id
    (FiniteProduct.law (fun _ : Slots branch n => μ))

private theorem uniform_product {A B : Type*} [Fintype A] [Fintype B]
    [Nonempty A] [Nonempty B] :
    (FiniteDistribution.uniform A).product (FiniteDistribution.uniform B) =
      FiniteDistribution.uniform (A × B) := by
  apply FiniteDistribution.eq_of_weight_eq
  intro x
  simp only [FiniteDistribution.product, FiniteDistribution.uniform,
    Fintype.card_prod, Nat.cast_mul, one_div_mul_one_div]

private theorem uniform_equiv {A B : Type*} [Fintype A] [Fintype B]
    [Nonempty A] [Nonempty B] (e : A ≃ B) :
    (FiniteDistribution.uniform A).pushforward e = FiniteDistribution.uniform B := by
  rw [FiniteDistribution.pushforward_equiv]
  apply FiniteDistribution.eq_of_weight_eq
  intro x
  change 1 / (Fintype.card A : ℝ) = 1 / (Fintype.card B : ℝ)
  rw [Fintype.card_congr e]

theorem sourceLaw_uniform [NeZero m] (designated : Fin (branch n) → Slots branch n) :
    sourceLaw m t designated =
      FiniteDistribution.uniform (SourceChildKernel.Sources (m := m) (t := t) designated) := by
  simp only [sourceLaw, SourceOddLists.tupleLaw, FiniteDistribution.iid_uniform,
    UniformLinearImage.law_uniform, uniform_product]

theorem assemble_law [NeZero m] (designated : Fin (branch n) → Slots branch n) :
    (sourceLaw m t designated).pushforward (assembleEquiv (m := m) (t := t) designated) =
      FiniteDistribution.uniform (Slots branch (n + 1) → SourceTuple m t) := by
  rw [sourceLaw_uniform]
  exact uniform_equiv _

def questions (designated : Fin (branch n) → Slots branch n)
    (sources : SourceChildKernel.Sources (m := m) (t := t) designated) :
    PreliminarySampler.Questions branch (n + 1) t m :=
  fun leaf k => (assembleEquiv designated sources leaf k).1

private def splitPositions :
    (Slots branch (n + 1) → SourceTuple m t) ≃
      (PreliminarySampler.Questions branch (n + 1) t m ×
        (Slots branch (n + 1) → Fin t → Fin 3)) where
  toFun tree := (fun leaf k => (tree leaf k).1, fun leaf k => (tree leaf k).2)
  invFun parts leaf k := (parts.1 leaf k, parts.2 leaf k)
  left_inv _ := rfl
  right_inv _ := rfl

theorem questions_law [NeZero m] (designated : Fin (branch n) → Slots branch n) :
    (sourceLaw m t designated).pushforward (questions designated) =
      PreliminarySampler.questionsLaw (branch := branch) (n := n + 1) (t := t) (m := m) := by
  let e := splitPositions (branch := branch) (n := n) (m := m) (t := t)
  calc
    _ = (((sourceLaw m t designated).pushforward
        (assembleEquiv (m := m) (t := t) designated)).pushforward e).pushforward Prod.fst := by
      rw [FiniteDistribution.pushforward_comp, FiniteDistribution.pushforward_comp]; rfl
    _ = ((FiniteDistribution.uniform (Slots branch (n + 1) → SourceTuple m t)).pushforward e).pushforward
        Prod.fst := by rw [assemble_law]
    _ = (FiniteDistribution.uniform
        (PreliminarySampler.Questions branch (n + 1) t m ×
          (Slots branch (n + 1) → Fin t → Fin 3))).pushforward Prod.fst := by
      rw [uniform_equiv]
    _ = _ := by
      rw [← uniform_product, HiddenBucketBias.product_fst]; rfl

theorem parentLeftSlots_eq (clauses : Fin m → SourceClause.NormalizedClause v)
    (designated : Fin (branch n) → Slots branch n)
    (sources : SourceChildKernel.Sources (m := m) (t := t) designated) :
    SourceChildKernel.parentLeftSlots clauses designated sources =
      HierarchicalArrays.sourceSlots clauses (PreliminarySampler.endpoints (questions designated sources)) := rfl

theorem originalLaw_sources {C : Type*} [Fintype C] [NeZero m]
    (rows : Nat → Nat) (clauses : Fin m → SourceClause.NormalizedClause v)
    (designated : Fin (branch n) → Slots branch n)
    (flag : Fin (branch n) → FiniteDistribution Bool) :
    (SourceChildKernel.originalLaw (C := C) (t := t) rows clauses designated flag).pushforward
        (SourceChildKernelMarginal.sources rows clauses designated) = sourceLaw m t designated :=
  SourceChildKernelMarginal.originalLaw_sources rows clauses designated flag

theorem originalLaw_questions {C : Type*} [Fintype C] [NeZero m]
    (rows : Nat → Nat) (clauses : Fin m → SourceClause.NormalizedClause v)
    (designated : Fin (branch n) → Slots branch n)
    (flag : Fin (branch n) → FiniteDistribution Bool) :
    (SourceChildKernel.originalLaw (C := C) (t := t) rows clauses designated flag).pushforward
        (fun sample => questions designated (SourceChildKernelMarginal.sources rows clauses designated sample)) =
      PreliminarySampler.questionsLaw (branch := branch) (n := n + 1) (t := t) (m := m) := by
  rw [← FiniteDistribution.pushforward_comp
    (SourceChildKernel.originalLaw (C := C) (t := t) rows clauses designated flag)
    (SourceChildKernelMarginal.sources rows clauses designated) (questions designated), originalLaw_sources]
  exact questions_law designated

end
end PerfectCompleteness.SourceChildQuestionLaw

end

end OAI