File size: 13,489 Bytes
92416a2
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
import Mathlib
import OAI.Computability.VertexCover.PCP.GenericGraphTables
import OAI.Computability.VertexCover.PCP.AlphabetTableEnumeration
import OAI.Computability.VertexCover.PCP.AlphabetTableRelations

namespace OAI

                                                                                            

namespace UniqueGames.Foundations.PCP.AlphabetTable.Table

variable {q : Nat}

def rowFromDart (input : GenericGraphTables.Table q)
    (dart : QueryIncidence.Dart (AlphabetGraph.Event (Fin input.darts) (Fin q)) 6) :
    GraphTables.DartRow (Enumeration.vertexCount input.vertices input.darts q)
      (Enumeration.dartCount input.darts q) :=
  let edge := dart.1.1.1
  let event := dart.1.1.2
  let slot := dart.1.2
  let old := input.rows[edge]
  let head := input.rows[old.reverseIndex].tail
  { tail := Enumeration.vertexEquiv input.vertices input.darts q
      (if dart.2 then
        .inr (Queries.globalize old.tail head edge
          (Queries.query (GenericGraphTables.relationAt old.relation) event slot))
      else .inl (edge, event))
    reverseIndex := Enumeration.dartEquiv input.darts q (dart.1, !dart.2)
    relation := Relations.relationFromTable old.relation (decide (old.tail = head))
      event slot dart.2 }

def rows (input : GenericGraphTables.Table q) :
    GraphTables.Rows (Enumeration.vertexCount input.vertices input.darts q)
      (Enumeration.dartCount input.darts q) :=
  Vector.ofFn (fun index =>
    rowFromDart input ((Enumeration.dartEquiv input.darts q).symm index))

@[simp] theorem rows_at (input : GenericGraphTables.Table q)
    (index : Fin (Enumeration.dartCount input.darts q)) :
    (rows input)[index] =
      rowFromDart input ((Enumeration.dartEquiv input.darts q).symm index) := by
  simp [rows]

theorem rows_reverseIndex (input : GenericGraphTables.Table q)
    (index : Fin (Enumeration.dartCount input.darts q)) :
    (rows input)[index].reverseIndex =
      Enumeration.dartEquiv input.darts q
        (((Enumeration.dartEquiv input.darts q).symm index).1,
          !((Enumeration.dartEquiv input.darts q).symm index).2) := by
  simp [rows, rowFromDart]

private theorem dartRow_ext {n m : Nat} {left right : GraphTables.DartRow n m}
    (ht : left.tail = right.tail) (hr : left.reverseIndex = right.reverseIndex)
    (hp : left.relation = right.relation) : left = right := by
  cases left
  cases right
  cases ht
  cases hr
  cases hp
  rfl

private theorem relation_ext {left right : GraphTables.RelationTable}
    (h : ∀ a b, GraphTables.relationAt left a b = GraphTables.relationAt right a b) :
    left = right := by
  apply Vector.ext
  intro i hi
  let labels := GraphTables.relationIndex.symm (⟨i, hi⟩ : Fin 4096)
  have index : GraphTables.relationIndex labels = (⟨i, hi⟩ : Fin 4096) :=
    GraphTables.relationIndex.apply_symm_apply _
  have point := h labels.1 labels.2
  simpa only [GraphTables.relationAt, index, Fin.getElem_fin] using point

theorem rowFromDart_eq_graphRow (input : GenericGraphTables.Table q)
    (dart : QueryIncidence.Dart (AlphabetGraph.Event (Fin input.darts) (Fin q)) 6) :
    rowFromDart input dart =
      { tail := Enumeration.vertexEquiv input.vertices input.darts q
          ((AlphabetGraph.graph (GenericGraphTables.semantics input)).tail dart)
        reverseIndex := Enumeration.dartEquiv input.darts q
          ((AlphabetGraph.graph (GenericGraphTables.semantics input)).reverse dart)
        relation := GraphTables.relationOf (fun a b =>
          (AlphabetGraph.graph (GenericGraphTables.semantics input)).accepts dart
            (Enumeration.labelEquiv.symm a) (Enumeration.labelEquiv.symm b)) } := by
  rcases dart with ⟨⟨⟨edge, event⟩, slot⟩, orientation⟩
  apply dartRow_ext
  · cases orientation with
    | false => rfl
    | true =>
      have query := Queries.globalize_query (GenericGraphTables.semantics input)
        edge event slot
      have predicate : (GenericGraphTables.semantics input).accepts edge =
          GenericGraphTables.relationAt input.rows[edge].relation := rfl
      rw [predicate] at query
      simpa only [rowFromDart, AlphabetGraph.graph, QueryIncidence.graph,
        QueryIncidence.tail, GenericGraphTables.semantics_tail,
        ConstraintGraph.head, GenericGraphTables.semantics_reverse,
        ite_true] using
        congrArg (fun address => Enumeration.vertexEquiv input.vertices input.darts q
          (.inr address)) query
  · rfl
  · apply relation_ext
    intro a b
    rw [GraphTables.relationAt_relationOf]
    have relation := Relations.relationAt_relation_graph (GenericGraphTables.semantics input)
      edge event slot orientation a b
    have predicate : (GenericGraphTables.semantics input).accepts edge =
        Relations.oldPredicate input.rows[edge].relation := rfl
    rw [predicate] at relation
    simp only [rowFromDart, Relations.relationFromTable,
      GenericGraphTables.semantics_tail, ConstraintGraph.head,
      GenericGraphTables.semantics_reverse] at relation ⊢
    exact relation

theorem rows_eq_graphRows (input : GenericGraphTables.Table q) :
    rows input = GraphTables.graphRows
      (GraphTables.enumeratedGraph (AlphabetGraph.graph (GenericGraphTables.semantics input))
        (Enumeration.vertexEquiv input.vertices input.darts q)
        (Enumeration.dartEquiv input.darts q) Enumeration.labelEquiv) := by
  apply Vector.ext
  intro i hi
  simp only [rows, GraphTables.graphRows, Vector.getElem_ofFn]
  exact rowFromDart_eq_graphRow input
    ((Enumeration.dartEquiv input.darts q).symm ⟨i, hi⟩)

theorem rows_valid (input : GenericGraphTables.Table q) : GraphTables.Valid (rows input) := by
  rw [rows_eq_graphRows]
  exact GraphTables.graphRows_valid _

def build (input : GenericGraphTables.Table q) : GraphTables.Table where
  vertices := Enumeration.vertexCount input.vertices input.darts q
  darts := Enumeration.dartCount input.darts q
  rows := rows input
  valid := rows_valid input

@[simp] theorem build_vertices (input : GenericGraphTables.Table q) :
    (build input).vertices = Enumeration.vertexCount input.vertices input.darts q := rfl

@[simp] theorem build_darts (input : GenericGraphTables.Table q) :
    (build input).darts = Enumeration.dartCount input.darts q := rfl

private theorem table_rows_congr {n m : Nat} {left right : GraphTables.Rows n m}
    (h : left = right) (hl : GraphTables.Valid left) (hr : GraphTables.Valid right) :
    (⟨n, m, left, hl⟩ : GraphTables.Table) = ⟨n, m, right, hr⟩ := by
  subst right
  rfl

private theorem semantics_rows_congr {n m : Nat} {left right : GraphTables.Rows n m}
    (h : left = right) (hl : GraphTables.Valid left) (hr : GraphTables.Valid right) :
    GraphTables.semantics (⟨n, m, left, hl⟩ : GraphTables.Table) =
      GraphTables.semantics (⟨n, m, right, hr⟩ : GraphTables.Table) := by
  subst right
  rfl

theorem build_eq_ofEnumeratedGraph (input : GenericGraphTables.Table q) :
    build input =
      GraphTables.ofEnumeratedGraph (AlphabetGraph.graph (GenericGraphTables.semantics input))
        (Enumeration.vertexEquiv input.vertices input.darts q)
        (Enumeration.dartEquiv input.darts q) Enumeration.labelEquiv := by
  exact table_rows_congr (rows_eq_graphRows input) (rows_valid input)
    (GraphTables.graphRows_valid _)

theorem semantics_build (input : GenericGraphTables.Table q) :
    GraphTables.semantics (build input) =
      GraphTables.enumeratedGraph (AlphabetGraph.graph (GenericGraphTables.semantics input))
        (Enumeration.vertexEquiv input.vertices input.darts q)
        (Enumeration.dartEquiv input.darts q) Enumeration.labelEquiv := by
  exact (semantics_rows_congr (rows_eq_graphRows input) (rows_valid input)
    (GraphTables.graphRows_valid _)).trans (GraphTables.semantics_ofGraph _)

theorem decode_build (input : GenericGraphTables.Table q) :
    GraphTables.decodeTableBits (GraphTables.tableBits (build input)) =
      some (GraphTables.ofEnumeratedGraph
        (AlphabetGraph.graph (GenericGraphTables.semantics input))
        (Enumeration.vertexEquiv input.vertices input.darts q)
        (Enumeration.dartEquiv input.darts q) Enumeration.labelEquiv) := by
  rw [GraphTables.decodeTableBits_encoded, build_eq_ofEnumeratedGraph]

theorem edgeSatisfied_build (input : GenericGraphTables.Table q)
    (labeling : QueryIncidence.Vertex (AlphabetGraph.Event (Fin input.darts) (Fin q))
      (AlphabetGraph.Address (Fin input.vertices) (Fin input.darts) (Fin q)) →
        QueryIncidence.Label 6)
    (dart : QueryIncidence.Dart (AlphabetGraph.Event (Fin input.darts) (Fin q)) 6) :
    (GraphTables.semantics (build input)).edgeSatisfied
      (fun v => Enumeration.labelEquiv
        (labeling ((Enumeration.vertexEquiv input.vertices input.darts q).symm v)))
      (Enumeration.dartEquiv input.darts q dart) =
        (AlphabetGraph.graph (GenericGraphTables.semantics input)).edgeSatisfied labeling dart := by
  rw [semantics_build]
  exact GraphTables.enumeratedGraph_edgeSatisfied _ _ _ _ labeling dart

theorem rejectionCount_build (input : GenericGraphTables.Table q)
    (labeling : QueryIncidence.Vertex (AlphabetGraph.Event (Fin input.darts) (Fin q))
      (AlphabetGraph.Address (Fin input.vertices) (Fin input.darts) (Fin q)) →
        QueryIncidence.Label 6) :
    (GraphTables.semantics (build input)).rejectionCount
      (fun v => Enumeration.labelEquiv
        (labeling ((Enumeration.vertexEquiv input.vertices input.darts q).symm v))) =
        (AlphabetGraph.graph (GenericGraphTables.semantics input)).rejectionCount labeling := by
  rw [semantics_build]
  exact GraphTables.enumeratedGraph_rejectionCount _ _ _ _ labeling

theorem perfect_completeness [Nonempty (Fin q)] (input : GenericGraphTables.Table q)
    (satisfied : (GenericGraphTables.semantics input).Satisfiable) :
    (GraphTables.semantics (build input)).Satisfiable := by
  obtain ⟨labeling, accepted⟩ :=
    AlphabetGraph.perfect_completeness (GenericGraphTables.semantics input) satisfied
  refine ⟨fun v => Enumeration.labelEquiv
    (labeling ((Enumeration.vertexEquiv input.vertices input.darts q).symm v)), ?_⟩
  intro index
  have h := edgeSatisfied_build input labeling
    ((Enumeration.dartEquiv input.darts q).symm index)
  have index_eq := (Enumeration.dartEquiv input.darts q).apply_symm_apply index
  rw [index_eq] at h
  exact h.trans (accepted _)

theorem gap_transfer [Nonempty (Fin q)] (input : GenericGraphTables.Table q) (a b : Nat)
    (source : ∀ labeling : Fin input.vertices → Fin q,
      a * input.darts ≤ b * (GenericGraphTables.semantics input).rejectionCount labeling)
    (labeling : Fin (build input).vertices → GraphTables.Label) :
    a * (build input).darts ≤
      (b * 12288) * (GraphTables.semantics (build input)).rejectionCount labeling := by
  classical
  let lifted := fun vertex => Enumeration.labelEquiv.symm
    (labeling (Enumeration.vertexEquiv input.vertices input.darts q vertex))
  have h := AlphabetGraph.gap_transfer (GenericGraphTables.semantics input) a b
    (by simpa only [Fintype.card_fin] using source) lifted
  rw [Enumeration.card_dart] at h
  have counts := rejectionCount_build input lifted
  have restored : (fun v : Fin (build input).vertices => Enumeration.labelEquiv
      (lifted ((Enumeration.vertexEquiv input.vertices input.darts q).symm v))) = labeling := by
    funext v
    dsimp only [lifted]
    rw [Enumeration.labelEquiv.apply_symm_apply]
    exact congrArg labeling
      ((Enumeration.vertexEquiv input.vertices input.darts q).apply_symm_apply v)
  rw [restored] at counts
  rw [← counts] at h
  exact h

theorem rowList_eq_ordered (input : GenericGraphTables.Table q) :
    GraphTables.rowList (build input) =
      (Enumeration.ordered (Enumeration.dartEquiv input.darts q)).map
        (rowFromDart input) := by
  change (Vector.ofFn (fun index => rowFromDart input
      ((Enumeration.dartEquiv input.darts q).symm index))).toList =
    (List.ofFn (Enumeration.dartEquiv input.darts q).symm).map (rowFromDart input)
  simp only [Vector.toList_ofFn, List.map_ofFn, Function.comp_def]

theorem tableWords_eq_ordered (input : GenericGraphTables.Table q) :
    GraphTables.tableWords (build input) =
      [Enumeration.vertexCount input.vertices input.darts q,
        Enumeration.dartCount input.darts q] ++
        (Enumeration.ordered (Enumeration.dartEquiv input.darts q)).flatMap
          (fun dart => GraphTables.rowWords (rowFromDart input dart)) := by
  simp only [GraphTables.tableWords, rowList_eq_ordered, build_vertices, build_darts,
    List.flatMap_map]

@[simp] theorem rowList_length (input : GenericGraphTables.Table q) :
    (GraphTables.rowList (build input)).length = Enumeration.dartCount input.darts q := by
  exact GraphTables.rowList_length (build input)

theorem tableWords_length (input : GenericGraphTables.Table q) :
    (GraphTables.tableWords (build input)).length =
      2 + 4098 * Enumeration.dartCount input.darts q := by
  exact GraphTables.tableWords_length (build input)

theorem tableBits_length_le (input : GenericGraphTables.Table q) :
    (GraphTables.tableBits (build input)).length ≤
      Enumeration.vertexCount input.vertices input.darts q +
        Enumeration.dartCount input.darts q + 2 + Enumeration.dartCount input.darts q *
          (Enumeration.vertexCount input.vertices input.darts q +
            Enumeration.dartCount input.darts q + 8192) := by
  exact GraphTables.tableBits_length_le (build input)

end UniqueGames.Foundations.PCP.AlphabetTable.Table

end OAI