File size: 13,516 Bytes
5d5048e
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
import OAI.Combinatorics.LowSpaceSubsetSum.Streams.CountedTieGroup
import OAI.Combinatorics.LowSpaceSubsetSum.Search.StoppedStreamJoin

namespace OAI

/-! # Costed execution of the stopped sorted-stream join

Every read, key evaluation, callback and snapshot invokes its supplied counted
implementation. The resulting work follows the exact stopped query/report/copy
ledger. The unused control fuel is never traversed.
-/

namespace LowSpaceSubsetSum.CountedStreamJoin

universe u v s t w
variable {α : Type u} {β : Type v} {σ₁ : Type s} {σ₂ : Type t} {τ : Type w}

def potential (M C D : ℕ) (st : StreamJoin.State σ₁ σ₂ τ) : ℕ :=
  M * st.queries + C * st.reports + D * st.copies

def step (read₁ : σ₁ → Option (α × σ₁) × ℕ) (key₁ : α → ℤ × ℕ)
    (read₂ : σ₂ → Option (β × σ₂) × ℕ) (key₂ : β → ℤ × ℕ) (cells : β → ℕ)
    (report : α → β → τ → (τ × Bool) × ℕ) (clone : σ₂ → σ₂ × ℕ)
    (B fuel₁ fuel₂ : ℕ) (s : StreamJoin.State σ₁ σ₂ τ) :
    StreamJoin.State σ₁ σ₂ τ × ℕ :=
  if s.done then (s, 1) else
  let fetched₁ := read₁ s.left
  match fetched₁.1 with
  | none => ({ s with queries := s.queries + 1, done := true }, fetched₁.2 + 4)
  | some (x, left') =>
    let fetched₂ := read₂ s.right
    match fetched₂.1 with
    | none => ({ s with queries := s.queries + 2, done := true }, fetched₁.2 + fetched₂.2 + 5)
    | some (y, right') =>
      let k₁ := key₁ x
      let k₂ := key₂ y
      let base := fetched₁.2 + fetched₂.2 + k₁.2 + k₂.2 + 8
      if k₁.1 < k₂.1 then ({ s with left := left', queries := s.queries + 2 }, base)
      else if k₂.1 < k₁.1 then ({ s with right := right', queries := s.queries + 2 }, base)
      else
        let out := CountedTieGroup.run read₁ key₁ read₂ key₂ cells k₁.1 report clone
          B fuel₁ fuel₂ s.left s.right s.user
        (⟨out.1.outer.cursor, out.1.outer.state.last, out.1.outer.state.user,
          s.queries + 2 + out.1.outer.queries + out.1.fillQueries + out.1.outer.state.queries,
          s.reports + out.1.outer.state.reports,
          s.copies + (if out.1.snapshot then 1 else 0) + out.1.outer.state.restores,
          out.1.outer.halted⟩, base + out.2 + 8)

theorem step_value (read₁ : σ₁ → Option (α × σ₁) × ℕ) (key₁ : α → ℤ × ℕ)
    (read₂ : σ₂ → Option (β × σ₂) × ℕ) (key₂ : β → ℤ × ℕ) (cells : β → ℕ)
    (report : α → β → τ → (τ × Bool) × ℕ) (clone : σ₂ → σ₂ × ℕ)
    (hclone : ∀ s, (clone s).1 = s)
    (B fuel₁ fuel₂ : ℕ) (s : StreamJoin.State σ₁ σ₂ τ) :
    (step read₁ key₁ read₂ key₂ cells report clone B fuel₁ fuel₂ s).1 =
      StreamJoin.step (fun s => (read₁ s).1) (fun x => (key₁ x).1)
        (fun s => (read₂ s).1) (fun y => (key₂ y).1) (fun x y a => (report x y a).1)
        B fuel₁ fuel₂ s := by
  by_cases hd : s.done = true
  · simp only [step, StreamJoin.step, hd, ↓reduceIte]
  · cases h₁ : (read₁ s.left).1 with
    | none => simp only [step, StreamJoin.step, hd, Bool.false_eq_true, ↓reduceIte, h₁]
    | some z₁ =>
      rcases z₁ with ⟨x, left'⟩
      cases h₂ : (read₂ s.right).1 with
      | none => simp only [step, StreamJoin.step, hd, Bool.false_eq_true, ↓reduceIte, h₁, h₂]
      | some z₂ =>
        rcases z₂ with ⟨y, right'⟩
        simp only [step, StreamJoin.step, hd, Bool.false_eq_true, ↓reduceIte, h₁, h₂,
          CountedTieGroup.run_value read₁ key₁ read₂ key₂ cells _ report clone hclone]
        split_ifs <;> rfl

theorem step_work_potential
    (read₁ : σ₁ → Option (α × σ₁) × ℕ) (key₁ : α → ℤ × ℕ)
    (read₂ : σ₂ → Option (β × σ₂) × ℕ) (key₂ : β → ℤ × ℕ) (cells : β → ℕ)
    (report : α → β → τ → (τ × Bool) × ℕ) (clone : σ₂ → σ₂ × ℕ)
    (R₁ R₂ L₁ L₂ S C D : ℕ)
    (hr₁ : ∀ s, (read₁ s).2 ≤ R₁) (hr₂ : ∀ s, (read₂ s).2 ≤ R₂)
    (hk₁ : ∀ x, (key₁ x).2 ≤ L₁) (hk₂ : ∀ y, (key₂ y).2 ≤ L₂)
    (hs : ∀ y, cells y ≤ S) (hc : ∀ x y a, (report x y a).2 ≤ C)
    (hcopy : ∀ s, (clone s).2 ≤ D)
    (B fuel₁ fuel₂ : ℕ) (s : StreamJoin.State σ₁ σ₂ τ) :
    (step read₁ key₁ read₂ key₂ cells report clone B fuel₁ fuel₂ s).2 +
        potential (R₁ + R₂ + L₁ + L₂ + S + 64) C D s ≤
      potential (R₁ + R₂ + L₁ + L₂ + S + 64) C D
        (step read₁ key₁ read₂ key₂ cells report clone B fuel₁ fuel₂ s).1 +
          (R₁ + R₂ + L₁ + L₂ + S + 64) := by
  by_cases hd : s.done = true
  · simp only [step, hd, ↓reduceIte]
    omega
  · have hr := hr₁ s.left
    cases h₁ : (read₁ s.left).1 with
    | none =>
      simp only [step, hd, Bool.false_eq_true, ↓reduceIte, h₁, potential, Nat.mul_add, Nat.mul_one]
      omega
    | some z₁ =>
      rcases z₁ with ⟨x, left'⟩
      have hr' := hr₂ s.right
      cases h₂ : (read₂ s.right).1 with
      | none =>
        simp only [step, hd, Bool.false_eq_true, ↓reduceIte, h₁, h₂, potential, Nat.mul_add]
        omega
      | some z₂ =>
        rcases z₂ with ⟨y, right'⟩
        have hk := hk₁ x
        have hk' := hk₂ y
        have hg := CountedTieGroup.run_work read₁ key₁ read₂ key₂ cells (key₁ x).1 report clone
          R₁ R₂ L₁ L₂ S C D hr₁ hr₂ hk₁ hk₂ hs hc hcopy B fuel₁ fuel₂ s.left s.right s.user
        let out := CountedTieGroup.run read₁ key₁ read₂ key₂ cells (key₁ x).1 report clone
          B fuel₁ fuel₂ s.left s.right s.user
        change out.2 ≤ (R₁ + R₂ + L₁ + L₂ + S + 50) *
          (out.1.outer.queries + out.1.fillQueries + out.1.outer.state.queries + 1) +
          C * out.1.outer.state.reports +
          D * ((if out.1.snapshot then 1 else 0) + out.1.outer.state.restores) at hg
        have hmul := Nat.mul_le_mul_right
          (out.1.outer.queries + out.1.fillQueries + out.1.outer.state.queries + 1)
          (show R₁ + R₂ + L₁ + L₂ + S + 50 ≤ R₁ + R₂ + L₁ + L₂ + S + 64 by omega)
        simp only [step, hd, Bool.false_eq_true, ↓reduceIte, h₁, h₂]
        split
        · simp only [potential, Nat.mul_add]
          omega
        · split
          · simp only [potential, Nat.mul_add]
            omega
          · change (read₁ s.left).2 + (read₂ s.right).2 + (key₁ x).2 + (key₂ y).2 + 8 + out.2 + 8 +
              potential (R₁ + R₂ + L₁ + L₂ + S + 64) C D s ≤
              potential (R₁ + R₂ + L₁ + L₂ + S + 64) C D
                ⟨out.1.outer.cursor, out.1.outer.state.last, out.1.outer.state.user,
                  s.queries + 2 + out.1.outer.queries + out.1.fillQueries + out.1.outer.state.queries,
                  s.reports + out.1.outer.state.reports,
                  s.copies + (if out.1.snapshot then 1 else 0) + out.1.outer.state.restores,
                  out.1.outer.halted⟩ + _
            simp only [potential, Nat.mul_add, Nat.mul_one] at hg hmul ⊢
            omega

def runAcc (read₁ : σ₁ → Option (α × σ₁) × ℕ) (key₁ : α → ℤ × ℕ)
    (read₂ : σ₂ → Option (β × σ₂) × ℕ) (key₂ : β → ℤ × ℕ) (cells : β → ℕ)
    (report : α → β → τ → (τ × Bool) × ℕ) (clone : σ₂ → σ₂ × ℕ)
    (B fuel₁ fuel₂ : ℕ) : ℕ → StreamJoin.State σ₁ σ₂ τ → StreamJoin.StoppedResult σ₁ σ₂ τ × ℕ
  | 0, st => (⟨st, 0⟩, 1)
  | fuel + 1, st =>
    if st.done then (⟨st, 0⟩, 1) else
      let next := step read₁ key₁ read₂ key₂ cells report clone B fuel₁ fuel₂ st
      let out := runAcc read₁ key₁ read₂ key₂ cells report clone B fuel₁ fuel₂ fuel next.1
      (⟨out.1.state, out.1.steps + 1⟩, next.2 + out.2 + 3)

theorem runAcc_value (read₁ : σ₁ → Option (α × σ₁) × ℕ) (key₁ : α → ℤ × ℕ)
    (read₂ : σ₂ → Option (β × σ₂) × ℕ) (key₂ : β → ℤ × ℕ) (cells : β → ℕ)
    (report : α → β → τ → (τ × Bool) × ℕ) (clone : σ₂ → σ₂ × ℕ)
    (hclone : ∀ s, (clone s).1 = s) (B fuel₁ fuel₂ fuel : ℕ) (st : StreamJoin.State σ₁ σ₂ τ) :
    (runAcc read₁ key₁ read₂ key₂ cells report clone B fuel₁ fuel₂ fuel st).1 =
      StreamJoin.stoppedAcc (fun s => (read₁ s).1) (fun x => (key₁ x).1)
        (fun s => (read₂ s).1) (fun y => (key₂ y).1) (fun x y a => (report x y a).1)
        B fuel₁ fuel₂ fuel st := by
  induction fuel generalizing st with
  | zero => rfl
  | succ fuel ih =>
    by_cases hd : st.done = true
    · simp only [runAcc, StreamJoin.stoppedAcc, hd, ↓reduceIte]
    · simp only [runAcc, StreamJoin.stoppedAcc, hd, Bool.false_eq_true, ↓reduceIte, ih,
        step_value read₁ key₁ read₂ key₂ cells report clone hclone]

theorem runAcc_work
    (read₁ : σ₁ → Option (α × σ₁) × ℕ) (key₁ : α → ℤ × ℕ)
    (read₂ : σ₂ → Option (β × σ₂) × ℕ) (key₂ : β → ℤ × ℕ) (cells : β → ℕ)
    (report : α → β → τ → (τ × Bool) × ℕ) (clone : σ₂ → σ₂ × ℕ)
    (R₁ R₂ L₁ L₂ S C D : ℕ)
    (hr₁ : ∀ s, (read₁ s).2 ≤ R₁) (hr₂ : ∀ s, (read₂ s).2 ≤ R₂)
    (hk₁ : ∀ x, (key₁ x).2 ≤ L₁) (hk₂ : ∀ y, (key₂ y).2 ≤ L₂)
    (hs : ∀ y, cells y ≤ S) (hc : ∀ x y a, (report x y a).2 ≤ C)
    (hcopy : ∀ s, (clone s).2 ≤ D)
    (B fuel₁ fuel₂ fuel : ℕ) (st : StreamJoin.State σ₁ σ₂ τ) :
    (runAcc read₁ key₁ read₂ key₂ cells report clone B fuel₁ fuel₂ fuel st).2 +
        potential (R₁ + R₂ + L₁ + L₂ + S + 64) C D st ≤
      potential (R₁ + R₂ + L₁ + L₂ + S + 64) C D
        (runAcc read₁ key₁ read₂ key₂ cells report clone B fuel₁ fuel₂ fuel st).1.state +
      (R₁ + R₂ + L₁ + L₂ + S + 67) *
        (runAcc read₁ key₁ read₂ key₂ cells report clone B fuel₁ fuel₂ fuel st).1.steps + 1 := by
  induction fuel generalizing st with
  | zero => simp only [runAcc, Nat.mul_zero, Nat.add_zero]; omega
  | succ fuel ih =>
    by_cases hd : st.done = true
    · simp only [runAcc, hd, ↓reduceIte, Nat.mul_zero, Nat.add_zero]; omega
    · have hstep := step_work_potential read₁ key₁ read₂ key₂ cells report clone
        R₁ R₂ L₁ L₂ S C D hr₁ hr₂ hk₁ hk₂ hs hc hcopy B fuel₁ fuel₂ st
      have hi := ih (step read₁ key₁ read₂ key₂ cells report clone B fuel₁ fuel₂ st).1
      simp only [runAcc, hd, Bool.false_eq_true, ↓reduceIte, Nat.mul_add, Nat.mul_one]
      omega

/-- After initialization, control iterations can themselves be charged to
queries, giving a bound using only the original join ledger. -/
theorem run_work_queries
    (read₁ : σ₁ → Option (α × σ₁) × ℕ) (key₁ : α → ℤ × ℕ)
    (read₂ : σ₂ → Option (β × σ₂) × ℕ) (key₂ : β → ℤ × ℕ) (cells : β → ℕ)
    (report : α → β → τ → (τ × Bool) × ℕ) (clone : σ₂ → σ₂ × ℕ)
    (hclone : ∀ s, (clone s).1 = s) (R₁ R₂ L₁ L₂ S C D : ℕ)
    (hr₁ : ∀ s, (read₁ s).2 ≤ R₁) (hr₂ : ∀ s, (read₂ s).2 ≤ R₂)
    (hk₁ : ∀ x, (key₁ x).2 ≤ L₁) (hk₂ : ∀ y, (key₂ y).2 ≤ L₂)
    (hs : ∀ y, cells y ≤ S) (hc : ∀ x y a, (report x y a).2 ≤ C)
    (hcopy : ∀ s, (clone s).2 ≤ D)
    (B fuel₁ fuel₂ fuel : ℕ) (s₁ : σ₁) (s₂ : σ₂) (a : τ) :
    (runAcc read₁ key₁ read₂ key₂ cells report clone B fuel₁ fuel₂ fuel
      (StreamJoin.start s₁ s₂ a)).2 ≤
      (2 * (R₁ + R₂ + L₁ + L₂ + S) + 131) *
        (StreamJoin.run (fun s => (read₁ s).1) (fun x => (key₁ x).1)
          (fun s => (read₂ s).1) (fun y => (key₂ y).1) (fun x y a => (report x y a).1)
          B fuel₁ fuel₂ fuel s₁ s₂ a).queries +
      C * (StreamJoin.run (fun s => (read₁ s).1) (fun x => (key₁ x).1)
          (fun s => (read₂ s).1) (fun y => (key₂ y).1) (fun x y a => (report x y a).1)
          B fuel₁ fuel₂ fuel s₁ s₂ a).reports +
      D * (StreamJoin.run (fun s => (read₁ s).1) (fun x => (key₁ x).1)
          (fun s => (read₂ s).1) (fun y => (key₂ y).1) (fun x y a => (report x y a).1)
          B fuel₁ fuel₂ fuel s₁ s₂ a).copies + 1 := by
  have h := runAcc_work read₁ key₁ read₂ key₂ cells report clone
    R₁ R₂ L₁ L₂ S C D hr₁ hr₂ hk₁ hk₂ hs hc hcopy B fuel₁ fuel₂ fuel
    (StreamJoin.start s₁ s₂ a)
  rw [runAcc_value read₁ key₁ read₂ key₂ cells report clone hclone] at h
  have hq := StreamJoin.stopped_steps_le_queries (fun s => (read₁ s).1) (fun x => (key₁ x).1)
    (fun s => (read₂ s).1) (fun y => (key₂ y).1) (fun x y a => (report x y a).1)
    B fuel₁ fuel₂ fuel s₁ s₂ a
  have hmul := Nat.mul_le_mul_left (R₁ + R₂ + L₁ + L₂ + S + 67) hq
  simp only [potential, StreamJoin.start, Nat.mul_zero, Nat.add_zero,
    StreamJoin.stoppedAcc_eq] at h
  simp only [StreamJoin.stopped] at hmul
  dsimp only [StreamJoin.run, StreamJoin.start] at hmul ⊢
  have he : 2 * (R₁ + R₂ + L₁ + L₂ + S) + 131 =
      (R₁ + R₂ + L₁ + L₂ + S + 64) + (R₁ + R₂ + L₁ + L₂ + S + 67) := by omega
  rw [he, Nat.add_mul]
  omega

end LowSpaceSubsetSum.CountedStreamJoin

end OAI