File size: 7,297 Bytes
7d9f027
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
155
156
157
158
159
160
161
162
163
import Mathlib
import OAI.Probability.SKRatio.Calculus.RowControl
import OAI.Probability.SKRatio.Variational.CompactField

namespace OAI

section
noncomputable section
open scoped BigOperators Topology
open MeasureTheory ProbabilityTheory Filter Set Real
namespace SKRatio.Planted
open Scalar Calculus
attribute [local instance] Classical.propDecidable
variable {n : ℕ}

def quadratic (A : Matrix (Fin n) (Fin n) ℝ) (p : Fin n → ℝ) : ℝ :=
  ∑ i, ∑ j, A i j*p i*p j

def weightedForm (A : Matrix (Fin n) (Fin n) ℝ) (G : FieldWeight × FieldWeight → ℝ)
    (x : Fin n → FieldWeight) (p : Fin n → ℝ) : ℝ :=
  quadratic (fun i j => A i j*G (x i,x j)) p

def diagonalForm (A : Matrix (Fin n) (Fin n) ℝ) (G : FieldWeight × FieldWeight → ℝ)
    (x : Fin n → FieldWeight) (p : Fin n → ℝ) : ℝ :=
  ∑ i, (∑ j, A i j*G (x i,x j))*p i^2

def varianceKernel (p : FieldWeight × FieldWeight) : ℝ := compactV p.2
def meanVarianceKernel (p : FieldWeight × FieldWeight) : ℝ :=
  (1-(p.2:ℝ))*compactV p.2

lemma continuous_varianceKernel : Continuous varianceKernel :=
  continuous_compactV.comp continuous_snd
lemma continuous_meanVarianceKernel : Continuous meanVarianceKernel := by
  unfold meanVarianceKernel
  exact (continuous_const.sub (continuous_subtype_val.comp continuous_snd)).mul
    (continuous_compactV.comp continuous_snd)

def compactForm (J : Interaction n) (x : Fin n → FieldWeight) (p : Fin n → ℝ) : ℝ :=
  weightedForm J varianceKernel x p +
  2*weightedForm (fun i j => J i j^2) meanVarianceKernel x p +
  diagonalForm (fun i j => J i j^2) compactF x p +
  weightedForm (fun i j => J i j^2) compactK x p

lemma quadratic_add (A B : Matrix (Fin n) (Fin n) ℝ) (p : Fin n → ℝ) :
    quadratic (A+B) p = quadratic A p+quadratic B p := by
  simp only [quadratic,Matrix.add_apply,add_mul,Finset.sum_add_distrib]
lemma quadratic_sub (A B : Matrix (Fin n) (Fin n) ℝ) (p : Fin n → ℝ) :
    quadratic (A-B) p = quadratic A p-quadratic B p := by
  simp only [quadratic,Matrix.sub_apply,sub_mul,Finset.sum_sub_distrib]
lemma quadratic_const_mul (a : ℝ) (A : Matrix (Fin n) (Fin n) ℝ) (p : Fin n → ℝ) :
    quadratic (a • A) p = a*quadratic A p := by
  simp only [quadratic,Matrix.smul_apply,smul_eq_mul,mul_assoc,←Finset.mul_sum]

lemma quadratic_inner (A : Matrix (Fin n) (Fin n) ℝ) (p : Fin n → ℝ) :
    quadratic A p = inner ℝ (WithLp.toLp 2 p)
      (Matrix.toEuclideanCLM (𝕜 := ℝ) (n := Fin n) A (WithLp.toLp 2 p)) := by
  rw [Matrix.inner_toEuclideanCLM]
  simp only [quadratic,dotProduct,Matrix.mulVec,Finset.mul_sum]
  congr 1
  ext i
  apply Finset.sum_congr rfl
  intro j _
  ring

lemma quadratic_abs_le (A : Matrix (Fin n) (Fin n) ℝ) (p : Fin n → ℝ) :
    |quadratic A p| ≤ euclideanOpNorm A*(∑ i, p i^2) := by
  rw [quadratic_inner]
  let P : EuclideanSpace ℝ (Fin n) := WithLp.toLp 2 p
  have hb := (abs_real_inner_le_norm P (Matrix.toEuclideanCLM (𝕜 := ℝ) A P)).trans
    (mul_le_mul_of_nonneg_left ((Matrix.toEuclideanCLM (𝕜 := ℝ) A).le_opNorm P) (norm_nonneg P))
  calc
    _ ≤ ‖P‖*(‖Matrix.toEuclideanCLM (𝕜 := ℝ) A‖*‖P‖) := hb
    _ = euclideanOpNorm A*(∑ i, p i^2) := by
      rw [show ‖P‖*(‖Matrix.toEuclideanCLM (𝕜 := ℝ) A‖*‖P‖) =
        euclideanOpNorm A*‖P‖^2 by unfold euclideanOpNorm; ring]
      rw [EuclideanSpace.real_norm_sq_eq]

lemma weightedForm_sub (A B : Matrix (Fin n) (Fin n) ℝ)
    (G : FieldWeight × FieldWeight → ℝ) (x : Fin n → FieldWeight) (p : Fin n → ℝ) :
    weightedForm A G x p-weightedForm B G x p = weightedForm (A-B) G x p := by
  simp only [weightedForm,quadratic,Matrix.sub_apply,sub_mul,Finset.sum_sub_distrib]

lemma diagonalForm_sub (A B : Matrix (Fin n) (Fin n) ℝ)
    (G : FieldWeight × FieldWeight → ℝ) (x : Fin n → FieldWeight) (p : Fin n → ℝ) :
    diagonalForm A G x p-diagonalForm B G x p = diagonalForm (A-B) G x p := by
  simp only [diagonalForm,Matrix.sub_apply,sub_mul,Finset.sum_sub_distrib]

lemma diagonalForm_abs_le (A : Matrix (Fin n) (Fin n) ℝ)
    (G : FieldWeight × FieldWeight → ℝ) (x : Fin n → FieldWeight) (p : Fin n → ℝ)
    {C : ℝ} (hC : ∀ i, |∑ j, A i j*G (x i,x j)| ≤ C) :
    |diagonalForm A G x p| ≤ C*∑ i, p i^2 := by
  apply (Finset.abs_sum_le_sum_abs _ _).trans
  calc
    _ ≤ ∑ i, C*p i^2 := Finset.sum_le_sum (fun i _ => by
      rw [abs_mul,abs_of_nonneg (sq_nonneg (p i))]
      exact mul_le_mul_of_nonneg_right (hC i) (sq_nonneg _))
    _ = _ := (Finset.mul_sum ..).symm

lemma sum_offdiag_eq_full {F : Fin n → Fin n → ℝ} (hF : ∀ i, F i i=0) :
    (∑ i, ∑ j ∈ Finset.univ.erase i, F i j) = ∑ i, ∑ j, F i j := by
  apply Finset.sum_congr rfl
  intro i _
  simpa only [hF i,add_zero] using Finset.sum_erase_add Finset.univ (F i) (Finset.mem_univ i)

lemma gradient_pair_expansion (J : Interaction n) (hJ : ∀ i j, J i j=J j i)
    (hdiag : ∀ i, J i i=0) (H p : Fin n → ℝ) :
    pairSum (fun i j => J i j^2*(v (H j)*p i+v (H i)*p j)^2/(w (H i)+w (H j))) =
      diagonalForm (fun i j => J i j^2) compactF (fun i => compactWeight (H i)) p +
      weightedForm (fun i j => J i j^2) compactK (fun i => compactWeight (H i)) p := by
  have hd : ∀ i, J i i^2*(v (H i)^2/(w (H i)+w (H i)))*p i^2=0 := by simp [hdiag]
  have hk : ∀ i, J i i^2*kernel (H i) (H i)*p i*p i=0 := by simp [hdiag]
  simp only [diagonalForm,weightedForm,quadratic,compactF_weight,compactK_weight,Finset.sum_mul]
  rw [←sum_offdiag_eq_full hd,←sum_offdiag_eq_full hk,sum_offdiag_pairs,sum_offdiag_pairs,←pairSum_add]
  unfold pairSum
  apply Finset.sum_congr rfl
  intro i _
  apply Finset.sum_congr rfl
  intro j _
  dsimp only []
  rw [hJ j i]
  dsimp [kernel]
  rw [add_comm (w (H j)) (w (H i))]
  ring

theorem gradientForm_eq_compactForm (J : Interaction n) (hJ : ∀ i j, J i j=J j i)
    (hdiag : ∀ i, J i i=0) (p : Fin n → ℝ) :
    gradientForm J p = compactForm J (fun i => compactWeight (∑ j, J i j)) p := by
  have hm (i : Fin n) : mean J (plusSpin n) i = m (∑ j, J i j) := by
    simp [mean,field,plusSpin,spin,m]
  have hv (i : Fin n) : conditionalVariance J (plusSpin n) i = v (∑ j, J i j) := by
    simp only [conditionalVariance,hm,v]
  have hw (i : Fin n) : gradientWeight J (plusSpin n) i = w (∑ j, J i j) := by
    simp [gradientWeight,plusSpin,spin,hm,w]
  simp only [gradientForm,hm,hv,hw,gradient_pair_expansion J hJ hdiag,
    compactForm,weightedForm,quadratic,varianceKernel,meanVarianceKernel,
    compactV_weight,compactWeight_coe]
  have h₁ : (∑ i, ∑ j ∈ Finset.univ.erase i, J i j*p i*v (∑ k, J j k)*p j) =
      ∑ i, ∑ j, J i j*v (∑ k, J j k)*p i*p j := by
    rw [sum_offdiag_eq_full (by intro i; simp [hdiag])]
    apply Finset.sum_congr rfl
    intro i _
    apply Finset.sum_congr rfl
    intro j _
    ring
  have h₂ : (∑ i, ∑ j ∈ Finset.univ.erase i, J i j^2*p i*m (∑ k, J j k)*v (∑ k, J j k)*p j) =
      ∑ i, ∑ j, J i j^2*((1-w (∑ k, J j k))*v (∑ k, J j k))*p i*p j := by
    rw [sum_offdiag_eq_full (by intro i; simp [hdiag])]
    apply Finset.sum_congr rfl
    intro i _
    apply Finset.sum_congr rfl
    intro j _
    simp only [w]
    ring
  rw [h₁,h₂]
  ring

end SKRatio.Planted

end
end

end OAI