File size: 3,284 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
import Mathlib
import OAI.Computability.VertexCover.Machines.ExpanderStep

namespace OAI

section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
section
                                    
section

namespace VertexCover.Machine.ExpandMachine
open UniqueGames.Foundations.PCP

@[simp] theorem lookup_fst_val {q v : ℕ} (T : ExpanderTables.Table v q) (x : Fin v × Fin q) :
    (ExpanderTables.lookup T x).1.val = (lookup q (T.rows.toList.map Fin.val,(x.1.val,x.2.val))).1 :=
  (congrArg Prod.fst (lookup_erase T x)).symm
@[simp] theorem lookup_snd_val {q v : ℕ} (T : ExpanderTables.Table v q) (x : Fin v × Fin q) :
    (ExpanderTables.lookup T x).2.val = (lookup q (T.rows.toList.map Fin.val,(x.1.val,x.2.val))).2 :=
  (congrArg Prod.snd (lookup_erase T x)).symm

@[simp] theorem index_val {v q : ℕ} (x : Fin v × Fin q) :
    (ExpanderTables.rowIndex v q x).val=x.2.val+q*x.1.val := rfl
@[simp] theorem index_inv_fst {v q : ℕ} (i : Fin (v*q)) :
    ((ExpanderTables.rowIndex v q).symm i).1.val=i.val/q := rfl
@[simp] theorem index_inv_snd {v q : ℕ} (i : Fin (v*q)) :
    ((ExpanderTables.rowIndex v q).symm i).2.val=i.val%q := rfl

 theorem stepRow_lookup {v d : ℕ} (T : ExpanderTables.Table v (d*d))
    (H : ExpanderTables.Table ((d*d)*(d*d)) d) (i : Fin ((v*((d*d)*(d*d)))*(d*d))) :
    stepRow d (H.rows.toList.map Fin.val) (erase ⟨v,T⟩,i.val) =
      (ExpanderTables.rowIndex _ _ (ExpanderTables.stepLookup T H
        ((ExpanderTables.rowIndex _ _).symm i))).val := by
  simp only [ExpanderTables.stepLookup,index_val,index_inv_fst,index_inv_snd,
    lookup_fst_val,lookup_snd_val]
  rfl

 theorem stepRow_source {v d : ℕ} (T : ExpanderTables.Table v (d*d))
    (H : ExpanderTables.Table ((d*d)*(d*d)) d) (i : Fin ((v*((d*d)*(d*d)))*(d*d))) :
    stepRow d (H.rows.toList.map Fin.val) (erase ⟨v,T⟩,i.val) =
      (ExpanderTables.step T H).rows[i].val := by
  rw [stepRow_lookup,← ExpanderTables.lookup_step]
  simp only [ExpanderTables.lookup,Equiv.apply_symm_apply,ExpanderTables.reverseIndex]

 def step {d : ℕ} (H : ExpanderTables.Table ((d*d)*(d*d)) d) (T : Input (d*d)) : Input (d*d) :=
  ⟨T.1*((d*d)*(d*d)),ExpanderTables.step T.2 H⟩

 theorem stepData_source {d : ℕ} (H : ExpanderTables.Table ((d*d)*(d*d)) d) (T : Input (d*d)) :
    stepData d (H.rows.toList.map Fin.val) (erase T)=erase (step H T) := by
  apply Prod.ext
  · rfl
  · apply List.ext_getElem
    · simp [stepData,erase,step]
    · intro i h₁ h₂
      simp only [stepData,List.getElem_map,List.getElem_range,erase,step,Vector.getElem_toList]
      exact stepRow_source T.2 H ⟨i, by simpa [stepData,erase] using h₁⟩

noncomputable def stepPoly {d : ℕ} (H : ExpanderTables.Table ((d*d)*(d*d)) d) :
    Poly (code (q := d*d)) code (step H) :=
  (stepDataPoly d (H.rows.toList.map Fin.val)).encodeCongr erase (fun _ => rfl) (fun T => by
    change dataCode _ = dataCode _
    rw [stepData_source])

end VertexCover.Machine.ExpandMachine
end


end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end

end OAI