File size: 5,325 Bytes
f61e547
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
import OAI.Probability.FreeIsing.Cavity.Homeomorph
import OAI.Probability.FreeIsing.Energy.CoupledAttenuation
import OAI.Probability.FreeIsing.Estimates.RelabelMeasure
import OAI.Probability.FreeIsing.Trees.Transitivity

namespace OAI

noncomputable section

open MeasureTheory ProbabilityTheory

namespace Problem367.CavityArray

variable {d : ℕ} {theta : ℝ}

def field (h0 : 0 ≤ theta) (h1 : theta < 1)
    (H : TreeVertex d → ℝ) (v w : TreeVertex d) : ℝ :=
  (cavityFromSites h0 h1 (H v, H w)).1

theorem continuous_field (h0 : 0 ≤ theta) (h1 : theta < 1) :
    Continuous (field (d := d) h0 h1) := by
  apply continuous_pi
  intro v
  apply continuous_pi
  intro w
  exact continuous_fst.comp ((continuous_cavityFromSites h0 h1).comp
    ((continuous_apply v).prodMk (continuous_apply w)))

theorem measurable_field (h0 : 0 ≤ theta) (h1 : theta < 1) :
    Measurable (field (d := d) h0 h1) :=
  (continuous_field h0 h1).measurable

theorem measurable_field_apply (h0 : 0 ≤ theta) (h1 : theta < 1)
    (v w : TreeVertex d) : Measurable (fun H => field h0 h1 H v w) :=
  (measurable_pi_apply w).comp ((measurable_pi_apply v).comp
    (measurable_field h0 h1))

theorem field_reverse (h0 : 0 ≤ theta) (h1 : theta < 1)
    (H : TreeVertex d → ℝ) (v w : TreeVertex d) :
    field h0 h1 H w v = (cavityFromSites h0 h1 (H v, H w)).2 := by
  exact congrArg Prod.fst (cavityFromSites_swap h0 h1 (H v, H w))

theorem field_spec (h0 : 0 ≤ theta) (h1 : theta < 1)
    (H : TreeVertex d → ℝ) (v w : TreeVertex d) :
    field h0 h1 H v w + cavityMessage theta (field h0 h1 H w v) = H v := by
  rw [field_reverse h0 h1 H v w]
  exact (cavityFromSites_spec h0 h1 (H v, H w)).1

theorem field_relabel (h0 : 0 ≤ theta) (h1 : theta < 1)
    (g : TreeAut d) (H : TreeVertex d → ℝ) (v w : TreeVertex d) :
    field h0 h1 (relabel g H) v w =
      field h0 h1 H (g.toEquiv.symm v) (g.toEquiv.symm w) := rfl

theorem field_neg (h0 : 0 ≤ theta) (h1 : theta < 1)
    (H : TreeVertex d → ℝ) (v w : TreeVertex d) :
    field h0 h1 (-H) v w = -field h0 h1 H v w := by
  exact congrArg Prod.fst (cavityFromSites_neg h0 h1 (H v, H w))

theorem field_zero (h0 : 0 ≤ theta) (h1 : theta < 1)
    (v w : TreeVertex d) : field h0 h1 0 v w = 0 := by
  have h := cavityFromSites_eq h0 h1 (z := (0, 0)) (p := (0, 0))
    (by simp)
  exact congrArg Prod.fst h

theorem field_site_bound (h0 : 0 ≤ theta) (h1 : theta < 1)
    (H : TreeVertex d → ℝ) (v w : TreeVertex d) :
    |field h0 h1 H v w - H v| ≤ Real.artanh theta :=
  (cavityFromSites_bound h0 h1 (H v, H w)).1

theorem field_sub_abs_le (h0 : 0 ≤ theta) (h1 : theta < 1)
    {H H' : TreeVertex d → ℝ} {M : ℝ} (v w : TreeVertex d)
    (hv : |H v - H' v| ≤ M) (hw : |H w - H' w| ≤ M) :
    |field h0 h1 H v w - field h0 h1 H' v w| ≤ M / (1 - theta) :=
  cavity_pair_sub_abs_le h0 h1
    (field_spec h0 h1 H v w) (field_spec h0 h1 H w v)
    (field_spec h0 h1 H' v w) (field_spec h0 h1 H' w v) hv hw

section Joining

abbrev SitePair (d : ℕ) := (TreeVertex d → ℝ) × (TreeVertex d → ℝ)

def pairRelabel (g : TreeAut d) : SitePair d → SitePair d :=
  Prod.map (relabel g) (relabel g)

theorem measurable_pairRelabel (g : TreeAut d) : Measurable (pairRelabel g) :=
  (measurable_relabel g).prodMap (measurable_relabel g)

theorem site_sub_identDistrib {ν : Measure (SitePair d)}
    (hinv : ∀ g : TreeAut d, MeasurePreserving (pairRelabel g) ν ν)
    (u v : TreeVertex d) :
    IdentDistrib (fun p : SitePair d => p.1 u - p.2 u)
      (fun p : SitePair d => p.1 v - p.2 v) ν ν := by
  obtain ⟨g, hg⟩ := exists_treeAut_map u v
  have hm (w : TreeVertex d) : Measurable (fun p : SitePair d => p.1 w - p.2 w) :=
    ((measurable_pi_apply w).comp measurable_fst).sub
      ((measurable_pi_apply w).comp measurable_snd)
  refine ⟨(hm u).aemeasurable, (hm v).aemeasurable, ?_⟩
  calc
    ν.map (fun p : SitePair d => p.1 u - p.2 u) =
        ν.map ((fun p : SitePair d => p.1 v - p.2 v) ∘ pairRelabel g) := by
      congr 1
      funext p
      simp [pairRelabel, relabel, ← hg]
    _ = (ν.map (pairRelabel g)).map (fun p : SitePair d => p.1 v - p.2 v) :=
      (Measure.map_map (hm v) (measurable_pairRelabel g)).symm
    _ = ν.map (fun p : SitePair d => p.1 v - p.2 v) := by rw [(hinv g).map_eq]

theorem integral_field_sub_sq_le {ν : Measure (SitePair d)}
    (h0 : 0 ≤ theta) (h1 : theta < 1)
    (hinv : ∀ g : TreeAut d, MeasurePreserving (pairRelabel g) ν ν)
    (o v w : TreeVertex d)
    (hInt : Integrable (fun p : SitePair d => (p.1 o - p.2 o) ^ 2) ν) :
    (∫ p, (field h0 h1 p.1 v w - field h0 h1 p.2 v w) ^ 2 ∂ν) ≤
      (∫ p : SitePair d, (p.1 o - p.2 o) ^ 2 ∂ν) / (1 - theta) ^ 2 := by
  have hv := (site_sub_identDistrib hinv o v).sq
  have hw := (site_sub_identDistrib hinv o w).sq
  exact integral_cavity_pair_sub_sq_le h0 h1
    ((measurable_field_apply h0 h1 v w).comp measurable_fst)
    ((measurable_field_apply h0 h1 v w).comp measurable_snd)
    (hv.integrable_snd hInt) (hw.integrable_snd hInt)
    (Filter.Eventually.of_forall (fun p =>
      ⟨field_spec h0 h1 p.1 v w, field_spec h0 h1 p.1 w v,
        field_spec h0 h1 p.2 v w, field_spec h0 h1 p.2 w v⟩))
    hv.integral_eq.symm.le hw.integral_eq.symm.le

end Joining

end Problem367.CavityArray

end

end OAI