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Add lean source and binary files (part 64)
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import OAI.Computability.WLIdentification.WordExpressions
namespace OAI
namespace WLIdentification
namespace WordExpressions.Expr
open StackModel.Command
theorem correct_cases {n} {e p q r : Expr n} (he : Correct e) (hp : Correct p)
(hq : Correct q) (hr : Correct r) : Correct (.cases e p q r) := by
intro B S env out base ho henv hc hb h s
have hb0 := hc base le_rfl
obtain ⟨a, ha, hea⟩ := he B S env base (base+1) (by omega)
(fun i => ⟨by have := (henv i).1; omega, by have := (henv i).1; omega⟩)
(hc.mono (by omega)) (by simp only [hb0, List.length_nil]; omega) h.1 s
let v := e.eval (S ∘ env)
let T := Function.update S base v.dropLast
have hread : Exec (StackModel.Command.read base) none (Function.update S base v)
v.getLast? T 1 := by
simpa only [StackModel.Command.read, Function.update_self, Function.update_idem, T] using
Exec.pop base (fun _ b => b) none (Function.update S base v)
have henv' : ∀ i, env i < base+1 ∧ env i ≠ out := by
intro i; have := henv i; omega
have henvEq : T ∘ env = S ∘ env := env_update S env base _ (fun i => (henv i).1)
have hout : T out = S out := Function.update_of_ne (by omega) _ _
have hex : ∃ b ≤ max (p.cost B) (max (q.cost B) (r.cost B))+2,
Exec (.branch Option.isSome
(.branch (fun x : Option Bool => x.getD false) (r.code env out (base+1)) (q.code env out (base+1)))
(p.code env out (base+1))) v.getLast? T none
(Function.update T out ((Expr.cases e p q r).eval (S ∘ env))) b := by
cases hv : v.getLast? with
| none =>
obtain ⟨b, hb', heb⟩ := hp B T env out (base+1) (by omega) henv' (update_clean hc)
(hout ▸ hb) (by rw [henvEq]; simpa only [show (e.eval (S ∘ env)).getLast? = none from hv] using h.2) none
refine ⟨b+1, by have := le_max_left (p.cost B) (max (q.cost B) (r.cost B)); omega, ?_⟩
simpa only [eval, show (e.eval (S ∘ env)).getLast? = none from hv, henvEq] using
(Exec.branch_false (c := .branch (fun x : Option Bool => x.getD false)
(r.code env out (base+1)) (q.code env out (base+1))) (test := Option.isSome) (by rfl) heb)
| some b => cases b with
| false =>
obtain ⟨b, hb', heb⟩ := hq B T env out (base+1) (by omega) henv' (update_clean hc)
(hout ▸ hb) (by rw [henvEq]; simpa only [show (e.eval (S ∘ env)).getLast? = some false from hv] using h.2) (some false)
have hh := Exec.branch_true (test := Option.isSome) (d := p.code env out (base+1)) (by rfl)
(Exec.branch_false (test := fun x : Option Bool => x.getD false) (c := r.code env out (base+1)) (by rfl) heb)
refine ⟨b+2, ?_, ?_⟩
· have := (le_max_left (q.cost B) (r.cost B)).trans (le_max_right (p.cost B) _); omega
· simpa only [eval, show (e.eval (S ∘ env)).getLast? = some false from hv,
henvEq, Nat.add_assoc, Nat.reduceAdd] using hh
| true =>
obtain ⟨b, hb', heb⟩ := hr B T env out (base+1) (by omega) henv' (update_clean hc)
(hout ▸ hb) (by rw [henvEq]; simpa only [show (e.eval (S ∘ env)).getLast? = some true from hv] using h.2) (some true)
have hh := Exec.branch_true (test := Option.isSome) (d := p.code env out (base+1)) (by rfl)
(Exec.branch_true (test := fun x : Option Bool => x.getD false) (d := q.code env out (base+1)) (by rfl) heb)
refine ⟨b+2, ?_, ?_⟩
· have := (le_max_right (q.cost B) (r.cost B)).trans (le_max_right (p.cost B) _); omega
· simpa only [eval, show (e.eval (S ∘ env)).getLast? = some true from hv,
henvEq, Nat.add_assoc, Nat.reduceAdd] using hh
obtain ⟨b, hb', heb⟩ := hex
obtain ⟨c, hc', hec⟩ := clear_exec base none (Function.update T out ((Expr.cases e p q r).eval (S ∘ env)))
have hv := e.length_le (S ∘ env) B h.1
have hlen : (Function.update T out ((Expr.cases e p q r).eval (S ∘ env)) base).length ≤ B := by
rw [Function.update_of_ne (by omega)]
simp only [T, Function.update_self]
exact (List.dropLast_sublist v).length_le.trans hv
have hlast : Function.update (Function.update T out ((Expr.cases e p q r).eval (S ∘ env))) base [] =
Function.update S out ((Expr.cases e p q r).eval (S ∘ env)) := by
rw [Function.update_comm (by omega : out ≠ base), Function.update_idem, ← hb0, Function.update_eq_self]
refine ⟨c+b+1+a, ?_, ?_⟩
· dsimp only [cost]; omega
· simpa only [code, hlast, Nat.add_assoc] using Exec.seq hea (Exec.seq hread (Exec.seq heb hec))
end WordExpressions.Expr
namespace WordExpressions.Expr
open StackModel.Command
theorem correct_loop {n} {c a : Expr n} {f : Expr (n+2)} (hcorr : Correct c)
(haCorr : Correct a) (hf : Correct f) : Correct (.loop c a f) := by
intro B S env out base ho henv hc hb h s
let ec := c.eval (S ∘ env)
let stage := stages f.eval (S ∘ env) (a.eval (S ∘ env))
have hb0 := hc base le_rfl
have henvlo : ∀ i, env i < base := fun i => (henv i).1
have hcB : ec.length ≤ B := c.length_le _ _ h.1
have hstage : ∀ i ≤ ec.length, (stage i).length ≤ B := by
intro i hi
cases i with
| zero => exact a.length_le _ _ h.2.1
| succ i => exact f.length_le _ _ (h.2.2 i (by change i < ec.length; omega))
obtain ⟨u, hu, heu⟩ := hcorr B S env base (base+1) (by omega)
(fun i => ⟨by have := henvlo i; omega, by have := henvlo i; omega⟩)
(hc.mono (by omega)) (by simp only [hb0, List.length_nil]; omega) h.1 s
let S₁ := Function.update S base ec
have hS₁env : S₁ ∘ env = S ∘ env := env_update S env base ec henvlo
have hS₁out : S₁ out = S out := Function.update_of_ne (by omega) _ _
obtain ⟨v, hv, hev⟩ := haCorr B S₁ env out (base+1) (by omega)
(fun i => ⟨by have := henvlo i; omega, (henv i).2⟩)
(update_clean hc) (hS₁out ▸ hb) (by rw [hS₁env]; exact h.2.1) none
let X (i : ℕ) := Function.update (Function.update S out (stage i)) (base+1) (List.replicate i false)
have hX : ∀ i, X i base = [] := by
intro i
simpa only [X, Function.update_of_ne (by omega : base ≠ base+1),
Function.update_of_ne (by omega : base ≠ out)] using hb0
let body := StackModel.Command.seq (copy out (base+2) (base+3))
(.seq (f.code (Fin.snoc (Fin.snoc env (base+1)) (base+2)) out (base+3))
(.seq (clear (base+2)) (.push (base+1) (fun _ => false))))
have hbody : ∀ i, 0 ≤ i → i < 0+ec.length → ∀ w s,
∃ t ≤ f.cost B+12*B+11, Exec body s (Function.update (X i) base w) none
(Function.update (X (i+1)) base w) t := by
intro i _ hi w s
simp only [zero_add] at hi
let T := Function.update (X i) base w
have hTclean : Clean T (base+2) :=
(((hc.mono (by omega)).update (by omega : out < base+2)).update (by omega : base+1 < base+2)).update (by omega)
have hTstash := hTclean (base+2) le_rfl
have hTtmp := hTclean (base+3) (by omega)
have hTidx : T (base+1) = List.replicate i false := by simp [T, X]
have hTout : T out = stage i := by
simp only [T, X, Function.update_of_ne (by omega : out ≠ base),
Function.update_of_ne (by omega : out ≠ base+1), Function.update_self]
obtain ⟨u, hu, heu⟩ := copy_exec out (base+2) (base+3) (by omega) (by omega) (by omega) s T
let W := Function.update T (base+2) (stage i)
have hcopy : Function.update (Function.update T (base+2) (T out)) (base+3) [] = W := by
rw [hTout]
apply Function.update_eq_self_iff.mpr
simp only [Function.update_of_ne (by omega : base+3 ≠ base+2), hTtmp]
rw [hcopy] at heu
have henv' : ∀ j : Fin (n+2),
(Fin.snoc (Fin.snoc env (base+1)) (base+2) : Fin (n+2) → ℕ) j < base+3 ∧
(Fin.snoc (Fin.snoc env (base+1)) (base+2) : Fin (n+2) → ℕ) j ≠ out := by
intro j
refine Fin.lastCases ?_ (fun j => ?_) j
· simp only [Fin.snoc_last]; omega
· simp only [Fin.snoc_castSucc]
refine Fin.lastCases ?_ (fun k => ?_) j
· simp only [Fin.snoc_last]; omega
· simp only [Fin.snoc_castSucc]; have := henv k; omega
have hWenv : W ∘ Fin.snoc (Fin.snoc env (base+1)) (base+2) =
Fin.snoc (Fin.snoc (S ∘ env) (List.replicate i false)) (stage i) := by
funext j
refine Fin.lastCases ?_ (fun j => ?_) j
· simp [W]
· simp only [Function.comp_apply, Fin.snoc_castSucc]
refine Fin.lastCases ?_ (fun k => ?_) j
· simpa only [Fin.snoc_last, W, Function.update_of_ne (by omega : base+1 ≠ base+2)] using hTidx
· simp only [Fin.snoc_castSucc, Function.comp_apply, W, T, X,
Function.update_of_ne (by have := henvlo k; omega : env k ≠ base+2),
Function.update_of_ne (by have := henvlo k; omega : env k ≠ base),
Function.update_of_ne (by have := henvlo k; omega : env k ≠ base+1),
Function.update_of_ne (henv k).2]
have hWout : W out = stage i := by
simpa only [W, Function.update_of_ne (by omega : out ≠ base+2)] using hTout
have hWclean : Clean W (base+3) := (hTclean.mono (by omega)).update (by omega)
obtain ⟨v, hv, hev⟩ := hf B W (Fin.snoc (Fin.snoc env (base+1)) (base+2)) out (base+3)
(by omega) henv' hWclean (hWout ▸ hstage i (by omega)) (by rw [hWenv]; exact h.2.2 i hi) none
have hnext : f.eval (W ∘ Fin.snoc (Fin.snoc env (base+1)) (base+2)) = stage (i+1) := by
rw [hWenv]; rfl
rw [hnext] at hev
obtain ⟨z, hz, hez⟩ := clear_exec (base+2) none (Function.update W out (stage (i+1)))
have hZlen : (Function.update W out (stage (i+1)) (base+2)).length ≤ B := by
rw [Function.update_of_ne (by omega)]
simpa only [W, Function.update_self] using hstage i (by omega)
let Z := Function.update (Function.update W out (stage (i+1))) (base+2) []
have hZ : Z = Function.update T out (stage (i+1)) := by
dsimp only [Z, W]
rw [Function.update_comm (by omega : out ≠ base+2), Function.update_idem,
← hTstash, Function.update_eq_self]
have hpush := Exec.push (base+1) (fun _ : Option Bool => false) none Z
have hfinal : Function.update Z (base+1) (Z (base+1) ++ [false]) = Function.update (X (i+1)) base w := by
rw [hZ]
funext j
by_cases hj : j = base
· subst j; simp only [T, X, Function.update_self, Function.update_of_ne (by omega : base ≠ base+1),
Function.update_of_ne (by omega : base ≠ out)]
by_cases hj' : j = base+1
· subst j
simp only [Function.update_self, Function.update_of_ne (by omega : base+1 ≠ base),
Function.update_of_ne (by omega : base+1 ≠ out), hTidx, X]
exact List.replicate_succ'.symm
by_cases hj'' : j = out
· subst j
simp only [T, X, Function.update_self, Function.update_of_ne hj, Function.update_of_ne hj']
· simp only [T, X, Function.update_of_ne hj, Function.update_of_ne hj', Function.update_of_ne hj'']
rw [hfinal] at hpush
refine ⟨1+z+v+u, ?_, ?_⟩
· simp only [hTstash, hTtmp, hTout, List.length_nil, mul_zero, zero_add] at hu
have hs := hstage i (by omega)
omega
· simpa only [body, Nat.add_assoc] using Exec.seq heu (Exec.seq hev (Exec.seq hez hpush))
obtain ⟨w, hw, hew⟩ := drain_indexed body base X hX (f.cost B+12*B+11) 0 ec hbody none
have hstart : Function.update (X 0) base ec = Function.update S₁ out (a.eval (S₁ ∘ env)) := by
rw [hS₁env]
dsimp only [X, stage, stages, List.replicate_zero, S₁]
rw [Function.update_comm (by omega : out ≠ base+1)]
have hh := hc (base+1) (by omega)
rw [← hh, Function.update_eq_self, Function.update_comm (by omega : out ≠ base)]
rw [hstart] at hew
simp only [zero_add] at hew
obtain ⟨z, hz, hez⟩ := clear_exec (base+1) none (X ec.length)
have hlast : Function.update (X ec.length) (base+1) [] =
Function.update S out ((Expr.loop c a f).eval (S ∘ env)) := by
dsimp only [X]
rw [Function.update_idem, Function.update_comm (by omega : out ≠ base+1)]
have hh := hc (base+1) (by omega)
rw [← hh, Function.update_eq_self]
rfl
have hlen : (X ec.length (base+1)).length = ec.length := by simp only [X, Function.update_self, List.length_replicate]
rw [hlen] at hz
rw [hlast] at hez
refine ⟨z+w+v+u, ?_, ?_⟩
· have hm := Nat.mul_le_mul_left (f.cost B+12*B+11+2) hcB
dsimp only [cost]
nlinarith
· simpa only [code, body, Nat.add_assoc] using Exec.seq heu (Exec.seq hev (Exec.seq hew hez))
/-- The finite word language executes on literal stacks, with polynomial cost
in the lengths of all values in its evaluation. -/
theorem correct {n} (e : Expr n) : e.Correct := by
induction e with
| var i => exact correct_var i
| nil => exact correct_nil
| snoc e b ih => exact correct_snoc ih b
| drop e ih => exact correct_drop ih
| cases e p q r he hp hq hr => exact correct_cases he hp hq hr
| bind e f he hf => exact correct_bind he hf
| loop c a f hc ha hf => exact correct_loop hc ha hf
end WordExpressions.Expr
namespace StackModel.Command
variable {R : Type}
def registers : Command ℕ R → Finset ℕ
| .skip | .modify _ => ∅
| .push k _ | .pop k _ => {k}
| .seq c d | .branch _ c d => c.registers ∪ d.registers
| .while _ c => c.registers
def small (c : Command ℕ R) (N : ℕ) : Prop := ∀ k ∈ c.registers, k < N
def finiteIndex (N : ℕ) (h : 0 < N) (k : ℕ) : Fin N := ⟨k % N, Nat.mod_lt _ h⟩
@[simp] theorem finiteIndex_val {N k} (h : 0 < N) (hk : k < N) :
(finiteIndex N h k).val = k := Nat.mod_eq_of_lt hk
theorem restrict_update {N k} (h : 0 < N) (hk : k < N) (S : ℕ → Word) (v : Word) :
Function.update S k v ∘ Fin.val = Function.update (S ∘ Fin.val) (finiteIndex N h k) v := by
funext j
by_cases hj : j.val = k
· have he : j = finiteIndex N h k := Fin.ext (hj.trans (finiteIndex_val h hk).symm)
simp only [Function.comp_apply, hj, Function.update_self]
rw [he, Function.update_self]
· have he : j ≠ finiteIndex N h k := by intro he; exact hj (congrArg Fin.val he |>.trans (finiteIndex_val h hk))
simp only [Function.comp_apply, Function.update_of_ne hj, Function.update_of_ne he]
/-- A syntactically finite register program has the same counted execution on
its finite set of tracks, even though its correctness was proved with convenient
natural register names. -/
theorem Exec.restrict {c : Command ℕ R} {s S t T n} (hex : Exec c s S t T n)
(N : ℕ) (hN : 0 < N) (hc : c.small N) :
Exec (c.rename (finiteIndex N hN)) s (S ∘ Fin.val) t (T ∘ Fin.val) n := by
induction hex with
| skip s S => exact .skip _ _
| modify f s S => exact .modify _ _ _
| push k f s S =>
have hk := hc k (by simp [registers])
simpa only [Command.rename, restrict_update hN hk, Function.comp_apply, finiteIndex_val hN hk] using
Exec.push (finiteIndex N hN k) f s (S ∘ Fin.val)
| pop k f s S =>
have hk := hc k (by simp [registers])
simpa only [Command.rename, restrict_update hN hk, Function.comp_apply, finiteIndex_val hN hk] using
Exec.pop (finiteIndex N hN k) f s (S ∘ Fin.val)
| seq _ _ ihc ihd =>
exact .seq (ihc (fun k hk => hc k (Finset.mem_union_left _ hk)))
(ihd (fun k hk => hc k (Finset.mem_union_right _ hk)))
| branch_true ht _ ih => exact .branch_true ht (ih (fun k hk => hc k (Finset.mem_union_left _ hk)))
| branch_false ht _ ih => exact .branch_false ht (ih (fun k hk => hc k (Finset.mem_union_right _ hk)))
| while_false test c s S ht => exact .while_false _ _ _ _ ht
| while_true ht _ _ ihc ihw => exact .while_true ht (ihc hc) (ihw hc)
theorem small_exists (c : Command ℕ R) : ∃ N, 1 < N ∧ c.small N := by
refine ⟨c.registers.sup id+2, by omega, ?_⟩
intro k hk
have h := Finset.le_sup (f := id) hk
dsimp only [id_eq] at h
omega
/-- A three-instruction output test after a structured command, followed by a
literal accepting or rejecting stack-machine halt. -/
def testProgram {K : Type} (c : Command K (Option Bool)) (s : Option Bool) (out : K) :
Program K (Option (Control c) ⊕ (Bool ⊕ Unit)) (Option Bool) where
main := .inl (some c.entry)
initialStore := s
code
| .inl (some x) => (c.code x).map Sum.inl
| .inl none => .pop out (fun _ b => b) (.inr (.inr ()))
| .inr (.inr _) => .branch (fun b => b.getD false) (.inr (.inl true)) (.inr (.inl false))
| .inr (.inl b) => .halt b
theorem testProgram_embeds {K : Type} (c : Command K (Option Bool)) (s : Option Bool) (out : K) :
Embeds (c.testProgram s out) c (Sum.inl ∘ some) (.inl none) := by
intro x
simp only [testProgram, Function.comp_apply]
congr 1
funext a
cases a <;> rfl
theorem Exec.testRun {K : Type} [DecidableEq K] {c : Command K (Option Bool)} {s S t T n}
(h : Exec c s S t T n) (input out : K) (w : Word)
(hS : S = Function.update (fun _ => []) input w) :
(StackModel.run (c.testProgram s out) input w (3+n)).control =
.inl ((T out).getLast?.getD false) := by
have he := h.execution (c.testProgram s out) (Sum.inl ∘ some) (.inl none)
(c.testProgram_embeds s out)
subst S
unfold StackModel.run
rw [Function.iterate_add_apply]
change ((StackModel.step (c.testProgram s out))^[3]
((StackModel.step (c.testProgram s out))^[n]
⟨.inr ((Sum.inl ∘ some) c.entry), s, Function.update (fun _ => []) input w⟩)).control = _
rw [he]
change (StackModel.step (c.testProgram s out) (StackModel.step (c.testProgram s out)
(StackModel.step (c.testProgram s out) ⟨.inr (.inl none), t, T⟩))).control = _
cases hb : (T out).getLast?.getD false <;> simp [StackModel.step, testProgram, hb]
end StackModel.Command
namespace ComputationBounds
def Polynomial (f : ℕ → ℕ) : Prop := ∃ C d : ℕ, ∀ n, f n ≤ C*(n+1)^d
theorem constant (c : ℕ) : Polynomial (fun _ => c) := ⟨c, 0, by simp⟩
theorem identity : Polynomial id := ⟨1, 1, by intro n; simp⟩
theorem add {f g} (hf : Polynomial f) (hg : Polynomial g) : Polynomial (fun n => f n+g n) := by
obtain ⟨C,d,hf⟩ := hf
obtain ⟨D,e,hg⟩ := hg
refine ⟨C+D, max d e, ?_⟩
intro n
have h1 := (hf n).trans (Nat.mul_le_mul_left C (Nat.pow_le_pow_right (by omega) (le_max_left d e)))
have h2 := (hg n).trans (Nat.mul_le_mul_left D (Nat.pow_le_pow_right (by omega) (le_max_right d e)))
nlinarith
theorem mul {f g} (hf : Polynomial f) (hg : Polynomial g) : Polynomial (fun n => f n*g n) := by
obtain ⟨C,d,hf⟩ := hf
obtain ⟨D,e,hg⟩ := hg
refine ⟨C*D, d+e, ?_⟩
intro n
have hh := Nat.mul_le_mul (hf n) (hg n)
calc
f n*g n ≤ (C*(n+1)^d)*(D*(n+1)^e) := hh
_ = (C*D)*(n+1)^(d+e) := by rw [pow_add]; ring
theorem maximum {f g} (hf : Polynomial f) (hg : Polynomial g) : Polynomial (fun n => max (f n) (g n)) := by
obtain ⟨C,d,h⟩ := add hf hg
exact ⟨C,d,fun n => (max_le (Nat.le_add_right _ _) (Nat.le_add_left _ _)).trans (h n)⟩
end ComputationBounds
namespace WordExpressions.Expr
open ComputationBounds
theorem cost_polynomial {n} (e : Expr n) : Polynomial e.cost := by
induction e with
| var _ => exact add (mul (constant 12) identity) (constant 8)
| nil => exact add (mul (constant 3) identity) (constant 2)
| snoc _ _ ih | drop _ ih => exact add ih (constant 1)
| cases _ _ _ _ he hp hq hr =>
exact add (add (add he (maximum hp (maximum hq hr))) (mul (constant 3) identity)) (constant 5)
| bind _ _ he hf => exact add (add (add he hf) (mul (constant 3) identity)) (constant 2)
| loop _ _ _ hc ha hf =>
exact add (add (add (add hc ha) (mul (add (add hf (mul (constant 12) identity)) (constant 13)) identity))
(mul (constant 3) identity)) (constant 4)
def outputBound {n} (e : Expr n) (B : ℕ) : ℕ :=
2+(e.cost B+15*B+13)*(2*(B+(e.cost B+15*B+13))+3)
theorem outputBound_polynomial {n} (e : Expr n) : Polynomial e.outputBound := by
have h := add (add e.cost_polynomial (mul (constant 15) identity)) (constant 13)
exact add (constant 2) (mul h (add (mul (constant 2) (add identity h)) (constant 3)))
end WordExpressions.Expr
end WLIdentification
end OAI