File size: 7,435 Bytes
8df23f4
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
164
165
166
167
168
169
170
171
172
173
174
175
import Mathlib.Algebra.BigOperators.Fin
import OAI.Computability.BinPacking.PCP.CloudRounding

namespace OAI

namespace BinPackingGames.Foundations.PCP.PoweringEnumeration

open PoweringLabels
open scoped BigOperators

def addressCount (d t : Nat) : Nat := ∑ i : Fin (t + 1), d ^ i.val

def reverseWordEquiv (d n : Nat) : (Fin n → Fin d) ≃ (Fin n → Fin d) where
  toFun p i := p i.rev
  invFun p i := p i.rev
  left_inv p := by funext i; simp only [Fin.rev_rev]
  right_inv p := by funext i; simp only [Fin.rev_rev]

def wordEquiv (d n : Nat) : (Fin n → Fin d) ≃ Fin (d ^ n) :=
  (reverseWordEquiv d n).trans finFunctionFinEquiv

theorem wordEquiv_val (d n : Nat) (p : Fin n → Fin d) :
    (wordEquiv d n p).val = ∑ i : Fin n, (p i.rev).val * d ^ i.val := rfl

def addressEquiv (d t : Nat) : PortWords (Fin d) t ≃ Fin (addressCount d t) :=
  (Equiv.sigmaCongrRight (fun i : Fin (t + 1) => wordEquiv d i.val)).trans
    finSigmaFinEquiv

theorem addressEquiv_val (d t : Nat) (w : PortWords (Fin d) t) :
    (addressEquiv d t w).val =
      (∑ i : Fin w.1.val, d ^ i.val) + (wordEquiv d w.1.val w.2).val := by
  change (finSigmaFinEquiv
    (⟨w.1, wordEquiv d w.1.val w.2⟩ : (i : Fin (t + 1)) × Fin (d ^ i.val))).val = _
  rw [finSigmaFinEquiv_apply]
  rfl

def paddedLabelEquiv (d t q : Nat) :
    PaddedLabel (Fin d) t (Fin q) ≃ Fin (q ^ addressCount d t) :=
  ((addressEquiv d t).arrowCongr (Equiv.refl (Fin q))).trans
    (wordEquiv q (addressCount d t))

theorem paddedLabelEquiv_val (d t q : Nat) (a : PaddedLabel (Fin d) t (Fin q)) :
    (paddedLabelEquiv d t q a).val =
      ∑ i : Fin (addressCount d t),
        (a ((addressEquiv d t).symm i.rev)).val * q ^ i.val := rfl

def orientationEquiv : Bool ≃ Fin 2 := finTwoEquiv.symm

@[simp] theorem orientationEquiv_false : orientationEquiv false = 0 := rfl
@[simp] theorem orientationEquiv_true : orientationEquiv true = 1 := rfl

def dartBlockEquiv (d n : Nat) :
    ((Fin (n + 1) → Fin d) × Bool) ≃ Fin (2 * d ^ (n + 1)) :=
  ((wordEquiv d (n + 1)).prodCongr orientationEquiv).trans
    (finProdFinEquiv.trans (finCongr (Nat.mul_comm (d ^ (n + 1)) 2)))

theorem dartBlockEquiv_val (d n : Nat) (p : Fin (n + 1) → Fin d) (b : Bool) :
    (dartBlockEquiv d n (p, b)).val =
      2 * (wordEquiv d (n + 1) p).val + (orientationEquiv b).val := by
  change (orientationEquiv b).val + 2 * (wordEquiv d (n + 1) p).val = _
  exact Nat.add_comm _ _

def dartVertexEquiv (vertices d n : Nat) :
    (Bool × (Fin vertices × (Fin (n + 1) → Fin d))) ≃
      (Fin vertices × ((Fin (n + 1) → Fin d) × Bool)) where
  toFun x := (x.2.1, (x.2.2, x.1))
  invFun x := (x.2.2, (x.1, x.2.1))
  left_inv x := by rcases x with ⟨b, v, p⟩; rfl
  right_inv x := by rcases x with ⟨v, p, b⟩; rfl

def dartEquiv (vertices d n : Nat) :
    (Bool × (Fin vertices × (Fin (n + 1) → Fin d))) ≃
      Fin (2 * vertices * d ^ (n + 1)) :=
  (dartVertexEquiv vertices d n).trans
    (((Equiv.refl (Fin vertices)).prodCongr (dartBlockEquiv d n)).trans
      (finProdFinEquiv.trans
        (finCongr (show vertices * (2 * d ^ (n + 1)) =
          2 * vertices * d ^ (n + 1) by ac_rfl))))

theorem dartEquiv_val (vertices d n : Nat) (b : Bool) (v : Fin vertices)
    (p : Fin (n + 1) → Fin d) :
    (dartEquiv vertices d n (b, (v, p))).val =
      (2 * d ^ (n + 1)) * v.val +
        2 * (wordEquiv d (n + 1) p).val + (orientationEquiv b).val := by
  change (dartBlockEquiv d n (p, b)).val + (2 * d ^ (n + 1)) * v.val = _
  rw [dartBlockEquiv_val]
  omega

theorem dartEquiv_true_eq_false_add_one (vertices d n : Nat) (v : Fin vertices)
    (p : Fin (n + 1) → Fin d) :
    (dartEquiv vertices d n (true, (v, p))).val =
      (dartEquiv vertices d n (false, (v, p))).val + 1 := by
  rw [dartEquiv_val, dartEquiv_val, orientationEquiv_true, orientationEquiv_false]
  rfl

def encodeWord (d n : Nat) : (Fin n → Fin d) → Fin (d ^ n) := wordEquiv d n
def decodeWord (d n : Nat) : Fin (d ^ n) → (Fin n → Fin d) := (wordEquiv d n).symm

@[simp] theorem decodeWord_encodeWord (d n : Nat) (p : Fin n → Fin d) :
    decodeWord d n (encodeWord d n p) = p := (wordEquiv d n).symm_apply_apply p

@[simp] theorem encodeWord_decodeWord (d n : Nat) (i : Fin (d ^ n)) :
    encodeWord d n (decodeWord d n i) = i := (wordEquiv d n).apply_symm_apply i

def encodeAddress (d t : Nat) : PortWords (Fin d) t → Fin (addressCount d t) :=
  addressEquiv d t

def decodeAddress (d t : Nat) : Fin (addressCount d t) → PortWords (Fin d) t :=
  (addressEquiv d t).symm

@[simp] theorem decodeAddress_encodeAddress (d t : Nat) (w : PortWords (Fin d) t) :
    decodeAddress d t (encodeAddress d t w) = w := (addressEquiv d t).symm_apply_apply w

@[simp] theorem encodeAddress_decodeAddress (d t : Nat) (i : Fin (addressCount d t)) :
    encodeAddress d t (decodeAddress d t i) = i := (addressEquiv d t).apply_symm_apply i

def encodeLabel (d t q : Nat) :
    PaddedLabel (Fin d) t (Fin q) → Fin (q ^ addressCount d t) := paddedLabelEquiv d t q

def decodeLabel (d t q : Nat) :
    Fin (q ^ addressCount d t) → PaddedLabel (Fin d) t (Fin q) :=
  (paddedLabelEquiv d t q).symm

@[simp] theorem decodeLabel_encodeLabel (d t q : Nat) (a : PaddedLabel (Fin d) t (Fin q)) :
    decodeLabel d t q (encodeLabel d t q a) = a := (paddedLabelEquiv d t q).symm_apply_apply a

@[simp] theorem encodeLabel_decodeLabel (d t q : Nat) (i : Fin (q ^ addressCount d t)) :
    encodeLabel d t q (decodeLabel d t q i) = i := (paddedLabelEquiv d t q).apply_symm_apply i

@[simp] theorem decodeLabel_apply (d t q : Nat) (i : Fin (q ^ addressCount d t))
    (w : PortWords (Fin d) t) :
    decodeLabel d t q i w = decodeWord q (addressCount d t) i (encodeAddress d t w) := rfl

def encodeDart (vertices d n : Nat) :
    (Bool × (Fin vertices × (Fin (n + 1) → Fin d))) →
      Fin (2 * vertices * d ^ (n + 1)) := dartEquiv vertices d n

def decodeDart (vertices d n : Nat) :
    Fin (2 * vertices * d ^ (n + 1)) →
      (Bool × (Fin vertices × (Fin (n + 1) → Fin d))) := (dartEquiv vertices d n).symm

@[simp] theorem decodeDart_encodeDart (vertices d n : Nat)
    (e : Bool × (Fin vertices × (Fin (n + 1) → Fin d))) :
    decodeDart vertices d n (encodeDart vertices d n e) = e :=
  (dartEquiv vertices d n).symm_apply_apply e

@[simp] theorem encodeDart_decodeDart (vertices d n : Nat)
    (i : Fin (2 * vertices * d ^ (n + 1))) :
    encodeDart vertices d n (decodeDart vertices d n i) = i :=
  (dartEquiv vertices d n).apply_symm_apply i

theorem card_words (d n : Nat) : Nat.card (Fin n → Fin d) = d ^ n := by
  simpa only [Nat.card_fin] using Nat.card_congr (wordEquiv d n)

theorem card_addresses (d t : Nat) :
    Nat.card (PortWords (Fin d) t) = addressCount d t := by
  simpa only [Nat.card_fin] using Nat.card_congr (addressEquiv d t)

theorem card_labels (d t q : Nat) :
    Nat.card (PaddedLabel (Fin d) t (Fin q)) = q ^ addressCount d t := by
  simpa only [Nat.card_fin] using Nat.card_congr (paddedLabelEquiv d t q)

theorem card_darts (vertices d n : Nat) :
    Nat.card (Bool × (Fin vertices × (Fin (n + 1) → Fin d))) =
      2 * vertices * d ^ (n + 1) := by
  simpa only [Nat.card_fin] using Nat.card_congr (dartEquiv vertices d n)

theorem length_allAddresses (d t : Nat) :
    (PoweringAddresses.allAddresses d t).length = addressCount d t :=
  PoweringAddresses.length_allAddresses d t

end BinPackingGames.Foundations.PCP.PoweringEnumeration

end OAI