File size: 5,998 Bytes
2fca478
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
import OAI.Geometry.PeriodicTiling.CycleTests
import OAI.Geometry.PeriodicTiling.SeedSymbols
import Mathlib.Data.Finset.Union
import Mathlib.Tactic.FinCases

namespace OAI

noncomputable section

namespace PeriodicTilingThree

variable {p : ℕ} [NeZero p]

def ordinaryCycle (p : ℕ) [NeZero p] : ZMod (p ^ 2) ↪ Channel p where
  toFun j := .inl ((ZMod.finEquiv (p ^ 2)).symm j)
  inj' _ _ h := (ZMod.finEquiv (p ^ 2)).symm.injective (Sum.inl.inj h)

def ordinaryCycleLabels (w : Word p) (j : ZMod (p ^ 2)) :
    Label p (ordinaryCycle p j) :=
  w ((ZMod.finEquiv (p ^ 2)).symm j)

def seedCycle (t : Fin 2) (n : Column p) : ZMod 2 ↪ Channel p where
  toFun j := Fin.cases (.inr t) (fun _ => .inl n) j
  inj' := by
    intro i j h
    fin_cases i <;> fin_cases j
    · rfl
    · change Sum.inr t = Sum.inl n at h
      cases h
    · change Sum.inl n = Sum.inr t at h
      cases h
    · rfl

@[simp] theorem seedCycle_zero
    {p : ℕ} [NeZero p]
    (t : Fin 2) (n : Column p) :
    seedCycle t n 0 = .inr t := rfl

@[simp] theorem seedCycle_one
    {p : ℕ} [NeZero p]
    (t : Fin 2) (n : Column p) :
    seedCycle t n 1 = .inl n := rfl

def seedCycleLabels (t : Fin 2) (n : Column p) (j : Symbol p) (z : ZMod 2) :
    Label p (seedCycle t n z) :=
  Fin.cases (motive := fun z : Fin 2 => Label p (seedCycle t n z))
    () (fun _ => j) z

@[simp] theorem seedCycleLabels_zero
    {p : ℕ} [NeZero p]
    (t : Fin 2) (n : Column p) (j : Symbol p) :
    seedCycleLabels t n j 0 = () := rfl

@[simp] theorem seedCycleLabels_one
    {p : ℕ} [NeZero p]
    (t : Fin 2) (n : Column p) (j : Symbol p) :
    seedCycleLabels t n j 1 = j := rfl

variable (E : EncodingParameters p)

theorem ordinaryCycle_exclusion_iff (w : Word p) (o : GraphOutputs E)
    (hdep : HasDependence E o) :
    (∀ F ∈ cycleTiles E (ordinaryCycle p) (ordinaryCycleLabels w),
      Tiles F (graph o)) ↔
      ∀ x, ¬ (∀ n : Column p, Active E o (.inl n) x (w n)) := by
  classical
  rw [cycle_exclusion_iff E (ordinaryCycle p) (ordinaryCycleLabels w) o hdep]
  constructor
  · intro h x hall
    obtain ⟨z, hz⟩ := h x
    exact hz (hall ((ZMod.finEquiv (p ^ 2)).symm z))
  · intro h x
    obtain ⟨n, hn⟩ := not_forall.mp (h x)
    refine ⟨(ZMod.finEquiv (p ^ 2)) n, ?_⟩
    exact Eq.mpr
      (congrArg (fun m : Column p => ¬ Active E o (.inl m) x (w m))
        ((ZMod.finEquiv (p ^ 2)).symm_apply_apply n)) hn

theorem seedCycle_exclusion_iff (t : Fin 2) (n : Column p) (j : Symbol p)
    (o : GraphOutputs E) (hdep : HasDependence E o) :
    (∀ F ∈ cycleTiles E (seedCycle t n) (seedCycleLabels t n j),
      Tiles F (graph o)) ↔
      ∀ x, ¬ (Active E o (.inr t) x () ∧ Active E o (.inl n) x j) := by
  classical
  rw [cycle_exclusion_iff E (seedCycle t n) (seedCycleLabels t n j) o hdep]
  constructor
  · intro h x hx
    obtain ⟨z, hz⟩ := h x
    fin_cases z
    · exact hz hx.1
    · exact hz hx.2
  · intro h x
    by_cases hs : Active E o (.inr t) x ()
    · refine ⟨1, ?_⟩
      change ¬ Active E o (.inl n) x j
      intro hj
      exact h x ⟨hs, hj⟩
    · exact ⟨0, hs⟩

def wordConstraintTiles : Finset (Finset (Ambient E)) := by
  classical
  exact (Finset.univ.filter (fun w : Word p => w ∉ allowedWords p)).biUnion
    (fun w => cycleTiles E (ordinaryCycle p) (ordinaryCycleLabels w))

def seedConstraintTiles : Finset (Finset (Ambient E)) := by
  classical
  exact (Finset.univ.filter (fun q : Fin 2 × Column p × Symbol p =>
      q.2.2 ≠ seedSymbol E q.1)).biUnion
    (fun q => cycleTiles E (seedCycle q.1 q.2.1) (seedCycleLabels q.1 q.2.1 q.2.2))

theorem nonempty_of_mem_wordConstraintTiles {F : Finset (Ambient E)}
    (hF : F ∈ wordConstraintTiles E) : F.Nonempty := by
  classical
  obtain ⟨w, _, hF⟩ := Finset.mem_biUnion.mp hF
  exact nonempty_of_mem_cycleTiles E (ordinaryCycle p) (ordinaryCycleLabels w) hF

theorem nonempty_of_mem_seedConstraintTiles {F : Finset (Ambient E)}
    (hF : F ∈ seedConstraintTiles E) : F.Nonempty := by
  classical
  obtain ⟨q, _, hF⟩ := Finset.mem_biUnion.mp hF
  exact nonempty_of_mem_cycleTiles E (seedCycle q.1 q.2.1)
    (seedCycleLabels q.1 q.2.1 q.2.2) hF

theorem wordConstraintTiles_iff (o : GraphOutputs E) (hdep : HasDependence E o) :
    (∀ F ∈ wordConstraintTiles E, Tiles F (graph o)) ↔
      ∀ x w, (∀ n : Column p, Active E o (.inl n) x (w n)) → Allowed p w := by
  classical
  constructor
  · intro h x w hw
    by_contra hnot
    have hcycle : ∀ F ∈ cycleTiles E (ordinaryCycle p) (ordinaryCycleLabels w),
        Tiles F (graph o) := by
      intro F hF
      apply h F
      apply Finset.mem_biUnion.mpr
      exact ⟨w, by simp [hnot], hF⟩
    exact (ordinaryCycle_exclusion_iff E w o hdep).mp hcycle x hw
  · intro h F hF
    obtain ⟨w, hw, hF⟩ := Finset.mem_biUnion.mp hF
    have hnot : ¬ Allowed p w := by simpa using (Finset.mem_filter.mp hw).2
    apply (ordinaryCycle_exclusion_iff E w o hdep).mpr ?_ F hF
    intro x hx
    exact hnot (h x w hx)

theorem seedConstraintTiles_iff (o : GraphOutputs E) (hdep : HasDependence E o) :
    (∀ F ∈ seedConstraintTiles E, Tiles F (graph o)) ↔
      ∀ t n x j, Active E o (.inr t) x () → Active E o (.inl n) x j →
        j = seedSymbol E t := by
  classical
  constructor
  · intro h t n x j hseed hord
    by_contra hj
    have hcycle : ∀ F ∈ cycleTiles E (seedCycle t n) (seedCycleLabels t n j),
        Tiles F (graph o) := by
      intro F hF
      apply h F
      apply Finset.mem_biUnion.mpr
      exact ⟨(t, n, j), Finset.mem_filter.mpr ⟨Finset.mem_univ _, hj⟩, hF⟩
    exact (seedCycle_exclusion_iff E t n j o hdep).mp hcycle x ⟨hseed, hord⟩
  · intro h F hF
    obtain ⟨⟨t, n, j⟩, hq, hF⟩ := Finset.mem_biUnion.mp hF
    have hj : j ≠ seedSymbol E t := (Finset.mem_filter.mp hq).2
    apply (seedCycle_exclusion_iff E t n j o hdep).mpr ?_ F hF
    intro x hx
    exact hj (h t n x j hx.1 hx.2)

end PeriodicTilingThree

end

end OAI