4.3. Random restrictions
-
FABL.deltaRandomSubsetWeight[complete] -
FABL.deltaRandomSubsetWeight_nonneg[complete] -
FABL.sum_deltaRandomSubsetWeight[complete] -
FABL.expectDeltaRandomSubset[complete] -
FABL.expectRandomRestriction[complete] -
FABL.coordRestrictionWeight[complete] -
FABL.sum_coordRestrictionWeight[complete] -
FABL.restrictionAssignmentWeight[complete] -
FABL.sum_restrictionAssignmentWeight[complete]
Definition 4.15. For \delta\in[0,1], a set J is a \delta-random
subset of a finite set N if each element of N is included independently
with probability \delta. A \delta-random restriction on
\{-1,1\}^n is a pair (\boldsymbol J\mid\boldsymbol z) obtained by first
drawing a \delta-random subset \boldsymbol J\subseteq[n] and then drawing
\boldsymbol z\sim\{-1,1\}^{\overline{\boldsymbol J}} uniformly. Coordinate i is
free if i\in\boldsymbol J and fixed otherwise. Equivalently, each
coordinate is independently free with probability \delta and fixed to
\pm1 with probability (1-\delta)/2 each.
Lean code for Definition4.3.1●9 declarations
Associated Lean declarations
-
FABL.deltaRandomSubsetWeight[complete]
-
FABL.deltaRandomSubsetWeight_nonneg[complete]
-
FABL.sum_deltaRandomSubsetWeight[complete]
-
FABL.expectDeltaRandomSubset[complete]
-
FABL.expectRandomRestriction[complete]
-
FABL.coordRestrictionWeight[complete]
-
FABL.sum_coordRestrictionWeight[complete]
-
FABL.restrictionAssignmentWeight[complete]
-
FABL.sum_restrictionAssignmentWeight[complete]
-
FABL.deltaRandomSubsetWeight[complete] -
FABL.deltaRandomSubsetWeight_nonneg[complete] -
FABL.sum_deltaRandomSubsetWeight[complete] -
FABL.expectDeltaRandomSubset[complete] -
FABL.expectRandomRestriction[complete] -
FABL.coordRestrictionWeight[complete] -
FABL.sum_coordRestrictionWeight[complete] -
FABL.restrictionAssignmentWeight[complete] -
FABL.sum_restrictionAssignmentWeight[complete]
-
defdefined in FABL/Chapter04/RandomRestrictions.leancomplete
def FABL.deltaRandomSubsetWeight (n : ℕ) (δ : ℝ) (J : Finset (Fin n)) : ℝ
def FABL.deltaRandomSubsetWeight (n : ℕ) (δ : ℝ) (J : Finset (Fin n)) : ℝ
Probability weight of a free set under a `δ`-random subset model.
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.deltaRandomSubsetWeight_nonneg (n : ℕ) {δ : ℝ} (hδ0 : 0 ≤ δ) (hδ1 : δ ≤ 1) (J : Finset (Fin n)) : 0 ≤ FABL.deltaRandomSubsetWeight n δ J
theorem FABL.deltaRandomSubsetWeight_nonneg (n : ℕ) {δ : ℝ} (hδ0 : 0 ≤ δ) (hδ1 : δ ≤ 1) (J : Finset (Fin n)) : 0 ≤ FABL.deltaRandomSubsetWeight n δ J
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.sum_deltaRandomSubsetWeight (n : ℕ) (δ : ℝ) : ∑ J, FABL.deltaRandomSubsetWeight n δ J = 1
theorem FABL.sum_deltaRandomSubsetWeight (n : ℕ) (δ : ℝ) : ∑ J, FABL.deltaRandomSubsetWeight n δ J = 1
The `δ`-random subset weights form a probability distribution.
-
defdefined in FABL/Chapter04/RandomRestrictions.leancomplete
def FABL.expectDeltaRandomSubset (n : ℕ) (δ : ℝ) (g : Finset (Fin n) → ℝ) : ℝ
def FABL.expectDeltaRandomSubset (n : ℕ) (δ : ℝ) (g : Finset (Fin n) → ℝ) : ℝ
Expectation under a `δ`-random free set.
-
defdefined in FABL/Chapter04/RandomRestrictions.leancomplete
def FABL.expectRandomRestriction (n : ℕ) (δ : ℝ) (g : (J : Finset (Fin n)) → FABL.FixedSignCube J → ℝ) : ℝ
def FABL.expectRandomRestriction (n : ℕ) (δ : ℝ) (g : (J : Finset (Fin n)) → FABL.FixedSignCube J → ℝ) : ℝ
O'Donnell, Definition 4.15: expectation over a `δ`-random restriction `(J | z)`.
-
defdefined in FABL/Chapter04/RandomRestrictions.leancomplete
def FABL.coordRestrictionWeight : FABL.CoordRestriction → ℝ
def FABL.coordRestrictionWeight : FABL.CoordRestriction → ℝ
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.sum_coordRestrictionWeight : ∑ c, FABL.coordRestrictionWeight c = 1
theorem FABL.sum_coordRestrictionWeight : ∑ c, FABL.coordRestrictionWeight c = 1
-
defdefined in FABL/Chapter04/RandomRestrictions.leancomplete
def FABL.restrictionAssignmentWeight {n : ℕ} (ρ : Fin n → FABL.CoordRestriction) : ℝ
def FABL.restrictionAssignmentWeight {n : ℕ} (ρ : Fin n → FABL.CoordRestriction) : ℝ
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.sum_restrictionAssignmentWeight {n : ℕ} : ∑ ρ, FABL.restrictionAssignmentWeight ρ = 1
theorem FABL.sum_restrictionAssignmentWeight {n : ℕ} : ∑ ρ, FABL.restrictionAssignmentWeight ρ = 1
-
FABL.extendedSignRestriction[complete] -
FABL.extendedSignRestriction_apply[complete] -
FABL.extendedSignRestriction_setCoordinate_of_not_mem[complete]
Definition 4.16. Given f:\{-1,1\}^n\to\mathbb R, free coordinates
I\subseteq[n], and a fixing z\in\{-1,1\}^{\overline I} of the remaining
coordinates, one may identify the restricted function
f_{I\mid z}:\{-1,1\}^I\to\mathbb R with its extension
f_{I\mid z}:\{-1,1\}^n\to\mathbb R that holds the coordinates in
\overline I fixed at z and ignores the values of those fixed
coordinates as free inputs. When dealing with random restrictions this
extension convention is the default.
Lean code for Definition4.3.2●3 declarations
Associated Lean declarations
-
FABL.extendedSignRestriction[complete]
-
FABL.extendedSignRestriction_apply[complete]
-
FABL.extendedSignRestriction_setCoordinate_of_not_mem[complete]
-
FABL.extendedSignRestriction[complete] -
FABL.extendedSignRestriction_apply[complete] -
FABL.extendedSignRestriction_setCoordinate_of_not_mem[complete]
-
defdefined in FABL/Chapter04/RandomRestrictions.leancomplete
def FABL.extendedSignRestriction.{u_1} {n : ℕ} {α : Type u_1} (f : FABL.SignCube n → α) (J : Finset (Fin n)) (z : FABL.FixedSignCube J) : FABL.SignCube n → α
def FABL.extendedSignRestriction.{u_1} {n : ℕ} {α : Type u_1} (f : FABL.SignCube n → α) (J : Finset (Fin n)) (z : FABL.FixedSignCube J) : FABL.SignCube n → α
O'Donnell, Definition 4.16: restricted function extended to the full cube.
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.extendedSignRestriction_apply.{u_1} {n : ℕ} {α : Type u_1} (f : FABL.SignCube n → α) (J : Finset (Fin n)) (z : FABL.FixedSignCube J) (x : FABL.SignCube n) : FABL.extendedSignRestriction f J z x = f (FABL.combineSignCube J (fun i => x ↑i) z)
theorem FABL.extendedSignRestriction_apply.{u_1} {n : ℕ} {α : Type u_1} (f : FABL.SignCube n → α) (J : Finset (Fin n)) (z : FABL.FixedSignCube J) (x : FABL.SignCube n) : FABL.extendedSignRestriction f J z x = f (FABL.combineSignCube J (fun i => x ↑i) z)
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.extendedSignRestriction_setCoordinate_of_not_mem.{u_1} {n : ℕ} {α : Type u_1} (f : FABL.SignCube n → α) (J : Finset (Fin n)) (z : FABL.FixedSignCube J) (i : Fin n) (hi : i ∉ J) (x : FABL.SignCube n) (b : FABL.Sign) : FABL.extendedSignRestriction f J z (FABL.setCoordinate x i b) = FABL.extendedSignRestriction f J z x
theorem FABL.extendedSignRestriction_setCoordinate_of_not_mem.{u_1} {n : ℕ} {α : Type u_1} (f : FABL.SignCube n → α) (J : Finset (Fin n)) (z : FABL.FixedSignCube J) (i : Fin n) (hi : i ∉ J) (x : FABL.SignCube n) (b : FABL.Sign) : FABL.extendedSignRestriction f J z (FABL.setCoordinate x i b) = FABL.extendedSignRestriction f J z x
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FABL.expect_fourierCoeff_empty_randomRestriction[complete] -
FABL.sum_deltaRandomSubsetWeight_supset[complete] -
FABL.ambientRestrictionFourierCoeff[complete] -
FABL.ambientRestrictionFourierCoeff_eq[complete] -
FABL.expect_ambientRestrictionFourierCoeff[complete] -
FABL.expect_fourierCoeff_randomRestriction[complete] -
FABL.liftFreeFrequency_freeFrequencyPart_of_subset[complete] -
FABL.expect_sq_ambientRestrictionFourierCoeff[complete] -
FABL.subset_of_inter_eq[complete] -
FABL.subset_of_inter_eq_left[complete] -
FABL.sum_deltaRandomSubsetWeight_inter_eq[complete] -
FABL.sum_sq_fourier_of_inter_eq[complete] -
FABL.expect_sq_fourierCoeff_randomRestriction[complete]
Proposition 4.17. Fix f:\{-1,1\}^n\to\mathbb R and S\subseteq[n]. If
(\boldsymbol J\mid\boldsymbol z) is a \delta-random restriction on
\{-1,1\}^n, then (treating restricted functions as maps
\{-1,1\}^n\to\mathbb R)
\mathbb E\bigl[\widehat{f_{\boldsymbol J\mid\boldsymbol z}}(S)\bigr]
=\Pr[S\subseteq\boldsymbol J]\,\widehat f(S)
=\delta^{|S|}\,\widehat f(S),
and
\mathbb E\bigl[\widehat{f_{\boldsymbol J\mid\boldsymbol z}}(S)^2\bigr]
=\sum_{U\subseteq[n]}\Pr[U\cap\boldsymbol J=S]\,\widehat f(U)^2
=\sum_{U\supseteq S}\delta^{|S|}(1-\delta)^{|U\setminus S|}\,\widehat f(U)^2.
For the first identity, use Corollary 3.22 and
\sum_{J\supseteq S}w_\delta(J)=\delta^{|S|}. For the second, apply the
free/fixed Parseval identity on each free set, reindex by the ambient
frequencies satisfying U\cap J=S, and use
\sum_{J:U\cap J=S}w_\delta(J)=\delta^{|S|}(1-\delta)^{|U\setminus S|} when S\subseteq U.
Lean code for Proposition4.3.3●13 declarations
Associated Lean declarations
-
FABL.expect_fourierCoeff_empty_randomRestriction[complete]
-
FABL.sum_deltaRandomSubsetWeight_supset[complete]
-
FABL.ambientRestrictionFourierCoeff[complete]
-
FABL.ambientRestrictionFourierCoeff_eq[complete]
-
FABL.expect_ambientRestrictionFourierCoeff[complete]
-
FABL.expect_fourierCoeff_randomRestriction[complete]
-
FABL.liftFreeFrequency_freeFrequencyPart_of_subset[complete]
-
FABL.expect_sq_ambientRestrictionFourierCoeff[complete]
-
FABL.subset_of_inter_eq[complete]
-
FABL.subset_of_inter_eq_left[complete]
-
FABL.sum_deltaRandomSubsetWeight_inter_eq[complete]
-
FABL.sum_sq_fourier_of_inter_eq[complete]
-
FABL.expect_sq_fourierCoeff_randomRestriction[complete]
-
FABL.expect_fourierCoeff_empty_randomRestriction[complete] -
FABL.sum_deltaRandomSubsetWeight_supset[complete] -
FABL.ambientRestrictionFourierCoeff[complete] -
FABL.ambientRestrictionFourierCoeff_eq[complete] -
FABL.expect_ambientRestrictionFourierCoeff[complete] -
FABL.expect_fourierCoeff_randomRestriction[complete] -
FABL.liftFreeFrequency_freeFrequencyPart_of_subset[complete] -
FABL.expect_sq_ambientRestrictionFourierCoeff[complete] -
FABL.subset_of_inter_eq[complete] -
FABL.subset_of_inter_eq_left[complete] -
FABL.sum_deltaRandomSubsetWeight_inter_eq[complete] -
FABL.sum_sq_fourier_of_inter_eq[complete] -
FABL.expect_sq_fourierCoeff_randomRestriction[complete]
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.expect_fourierCoeff_empty_randomRestriction {n : ℕ} (f : FABL.SignCube n → ℝ) (δ : ℝ) : (FABL.expectRandomRestriction n δ fun J z => FABL.restrictionFourierCoeff f J ∅ z) = FABL.fourierCoeff f ∅
theorem FABL.expect_fourierCoeff_empty_randomRestriction {n : ℕ} (f : FABL.SignCube n → ℝ) (δ : ℝ) : (FABL.expectRandomRestriction n δ fun J z => FABL.restrictionFourierCoeff f J ∅ z) = FABL.fourierCoeff f ∅
O'Donnell, Proposition 4.17 (empty-set first moment).
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.sum_deltaRandomSubsetWeight_supset (n : ℕ) (δ : ℝ) (S : Finset (Fin n)) : (∑ J, if S ⊆ J then FABL.deltaRandomSubsetWeight n δ J else 0) = δ ^ S.card
theorem FABL.sum_deltaRandomSubsetWeight_supset (n : ℕ) (δ : ℝ) (S : Finset (Fin n)) : (∑ J, if S ⊆ J then FABL.deltaRandomSubsetWeight n δ J else 0) = δ ^ S.card
Weight of free sets containing a fixed set `S` equals `δ ^ |S|`.
-
defdefined in FABL/Chapter04/RandomRestrictions.leancomplete
def FABL.ambientRestrictionFourierCoeff {n : ℕ} (f : FABL.SignCube n → ℝ) (J S : Finset (Fin n)) (z : FABL.FixedSignCube J) : ℝ
def FABL.ambientRestrictionFourierCoeff {n : ℕ} (f : FABL.SignCube n → ℝ) (J S : Finset (Fin n)) (z : FABL.FixedSignCube J) : ℝ
Free-cube Fourier coefficient of a restriction, zero unless `S ⊆ J`. This is the book’s first-moment input for Proposition 4.17 under the convention that frequencies outside the free set do not contribute.
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.ambientRestrictionFourierCoeff_eq {n : ℕ} (f : FABL.SignCube n → ℝ) (J S : Finset (Fin n)) (z : FABL.FixedSignCube J) : FABL.ambientRestrictionFourierCoeff f J S z = if S ⊆ J then FABL.restrictionFourierCoeff f J (FABL.freeFrequencyPart J S) z else 0
theorem FABL.ambientRestrictionFourierCoeff_eq {n : ℕ} (f : FABL.SignCube n → ℝ) (J S : Finset (Fin n)) (z : FABL.FixedSignCube J) : FABL.ambientRestrictionFourierCoeff f J S z = if S ⊆ J then FABL.restrictionFourierCoeff f J (FABL.freeFrequencyPart J S) z else 0
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.expect_ambientRestrictionFourierCoeff {n : ℕ} (f : FABL.SignCube n → ℝ) (J S : Finset (Fin n)) : (Finset.univ.expect fun z => FABL.ambientRestrictionFourierCoeff f J S z) = (if S ⊆ J then 1 else 0) * FABL.fourierCoeff f S
theorem FABL.expect_ambientRestrictionFourierCoeff {n : ℕ} (f : FABL.SignCube n → ℝ) (J S : Finset (Fin n)) : (Finset.univ.expect fun z => FABL.ambientRestrictionFourierCoeff f J S z) = (if S ⊆ J then 1 else 0) * FABL.fourierCoeff f S
Conditional first moment: free-set Fourier recovers ambient when `S ⊆ J`.
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.expect_fourierCoeff_randomRestriction {n : ℕ} (f : FABL.SignCube n → ℝ) (δ : ℝ) (S : Finset (Fin n)) : (FABL.expectRandomRestriction n δ fun J z => FABL.ambientRestrictionFourierCoeff f J S z) = δ ^ S.card * FABL.fourierCoeff f S
theorem FABL.expect_fourierCoeff_randomRestriction {n : ℕ} (f : FABL.SignCube n → ℝ) (δ : ℝ) (S : Finset (Fin n)) : (FABL.expectRandomRestriction n δ fun J z => FABL.ambientRestrictionFourierCoeff f J S z) = δ ^ S.card * FABL.fourierCoeff f S
O'Donnell, Proposition 4.17 (general first moment). `E[̂f_{J|z}(S)] = δ^{|S|} ̂f(S)`, with frequencies outside the free set treated as zero. -
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.liftFreeFrequency_freeFrequencyPart_of_subset {n : ℕ} {J S : Finset (Fin n)} (hS : S ⊆ J) : FABL.liftFreeFrequency (FABL.freeFrequencyPart J S) = S
theorem FABL.liftFreeFrequency_freeFrequencyPart_of_subset {n : ℕ} {J S : Finset (Fin n)} (hS : S ⊆ J) : FABL.liftFreeFrequency (FABL.freeFrequencyPart J S) = S
Lift of the free part of `S` recovers `S` when `S ⊆ J`.
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.expect_sq_ambientRestrictionFourierCoeff {n : ℕ} (f : FABL.SignCube n → ℝ) (J S : Finset (Fin n)) : (Finset.univ.expect fun z => FABL.ambientRestrictionFourierCoeff f J S z ^ 2) = if S ⊆ J then ∑ T, FABL.fourierCoeff f (FABL.liftFreeFrequency (FABL.freeFrequencyPart J S) ∪ FABL.liftFixedFrequency T) ^ 2 else 0
theorem FABL.expect_sq_ambientRestrictionFourierCoeff {n : ℕ} (f : FABL.SignCube n → ℝ) (J S : Finset (Fin n)) : (Finset.univ.expect fun z => FABL.ambientRestrictionFourierCoeff f J S z ^ 2) = if S ⊆ J then ∑ T, FABL.fourierCoeff f (FABL.liftFreeFrequency (FABL.freeFrequencyPart J S) ∪ FABL.liftFixedFrequency T) ^ 2 else 0
Conditional second moment via Corollary 3.22.
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.subset_of_inter_eq {n : ℕ} {S U J : Finset (Fin n)} (h : U ∩ J = S) : S ⊆ J
theorem FABL.subset_of_inter_eq {n : ℕ} {S U J : Finset (Fin n)} (h : U ∩ J = S) : S ⊆ J
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.subset_of_inter_eq_left {n : ℕ} {S U J : Finset (Fin n)} (h : U ∩ J = S) : S ⊆ U
theorem FABL.subset_of_inter_eq_left {n : ℕ} {S U J : Finset (Fin n)} (h : U ∩ J = S) : S ⊆ U
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.sum_deltaRandomSubsetWeight_inter_eq (n : ℕ) (δ : ℝ) (S U : Finset (Fin n)) : (∑ J, if U ∩ J = S then FABL.deltaRandomSubsetWeight n δ J else 0) = if S ⊆ U then δ ^ S.card * (1 - δ) ^ (U \ S).card else 0
theorem FABL.sum_deltaRandomSubsetWeight_inter_eq (n : ℕ) (δ : ℝ) (S U : Finset (Fin n)) : (∑ J, if U ∩ J = S then FABL.deltaRandomSubsetWeight n δ J else 0) = if S ⊆ U then δ ^ S.card * (1 - δ) ^ (U \ S).card else 0
Weight of free sets with fixed intersection `U ∩ J = S`.
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.sum_sq_fourier_of_inter_eq {n : ℕ} (f : FABL.SignCube n → ℝ) (J S : Finset (Fin n)) (hS : S ⊆ J) : ∑ T, FABL.fourierCoeff f (FABL.liftFreeFrequency (FABL.freeFrequencyPart J S) ∪ FABL.liftFixedFrequency T) ^ 2 = ∑ U, if U ∩ J = S then FABL.fourierCoeff f U ^ 2 else 0
theorem FABL.sum_sq_fourier_of_inter_eq {n : ℕ} (f : FABL.SignCube n → ℝ) (J S : Finset (Fin n)) (hS : S ⊆ J) : ∑ T, FABL.fourierCoeff f (FABL.liftFreeFrequency (FABL.freeFrequencyPart J S) ∪ FABL.liftFixedFrequency T) ^ 2 = ∑ U, if U ∩ J = S then FABL.fourierCoeff f U ^ 2 else 0
Ambient frequencies with free/fixed split relative to `J` matching free set `S`.
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.expect_sq_fourierCoeff_randomRestriction {n : ℕ} (f : FABL.SignCube n → ℝ) (δ : ℝ) (S : Finset (Fin n)) : (FABL.expectRandomRestriction n δ fun J z => FABL.ambientRestrictionFourierCoeff f J S z ^ 2) = ∑ U, (if S ⊆ U then δ ^ S.card * (1 - δ) ^ (U \ S).card else 0) * FABL.fourierCoeff f U ^ 2
theorem FABL.expect_sq_fourierCoeff_randomRestriction {n : ℕ} (f : FABL.SignCube n → ℝ) (δ : ℝ) (S : Finset (Fin n)) : (FABL.expectRandomRestriction n δ fun J z => FABL.ambientRestrictionFourierCoeff f J S z ^ 2) = ∑ U, (if S ⊆ U then δ ^ S.card * (1 - δ) ^ (U \ S).card else 0) * FABL.fourierCoeff f U ^ 2
O'Donnell, Proposition 4.17 (second moment).
-
FABL.sum_deltaRandomSubsetWeight_mem[complete] -
FABL.freePart[complete] -
FABL.discreteDerivative_extendedSignRestriction_of_mem[complete] -
FABL.expect_sq_discreteDerivative_combine[complete] -
FABL.expect_sq_discreteDerivative_product[complete] -
FABL.expect_influence_extendedSignRestriction_of_mem[complete] -
FABL.expect_influence_extended_randomRestriction[complete] -
FABL.expect_totalInfluence_extended_randomRestriction[complete]
Corollary 4.18. Fix f:\{-1,1\}^n\to\mathbb R and i\in[n]. If
(\boldsymbol J\mid\boldsymbol z) is a \delta-random restriction, then
\mathbb E[\operatorname{Inf}_i[f_{\boldsymbol J\mid\boldsymbol z}]]
=\delta\operatorname{Inf}_i[f]. Hence also
\mathbb E[\mathbf I[f_{\boldsymbol J\mid\boldsymbol z}]]=\delta\mathbf I[f].
A Fourier-free proof proceeds as in Exercise 4.9: condition on whether i
is free. In the free case, the free/fixed product measure recovers the
ambient influence, while \Pr[i\in\boldsymbol J]=\delta.
Lean code for Corollary4.3.4●8 declarations
Associated Lean declarations
-
FABL.sum_deltaRandomSubsetWeight_mem[complete]
-
FABL.freePart[complete]
-
FABL.discreteDerivative_extendedSignRestriction_of_mem[complete]
-
FABL.expect_sq_discreteDerivative_combine[complete]
-
FABL.expect_sq_discreteDerivative_product[complete]
-
FABL.expect_influence_extendedSignRestriction_of_mem[complete]
-
FABL.expect_influence_extended_randomRestriction[complete]
-
FABL.expect_totalInfluence_extended_randomRestriction[complete]
-
FABL.sum_deltaRandomSubsetWeight_mem[complete] -
FABL.freePart[complete] -
FABL.discreteDerivative_extendedSignRestriction_of_mem[complete] -
FABL.expect_sq_discreteDerivative_combine[complete] -
FABL.expect_sq_discreteDerivative_product[complete] -
FABL.expect_influence_extendedSignRestriction_of_mem[complete] -
FABL.expect_influence_extended_randomRestriction[complete] -
FABL.expect_totalInfluence_extended_randomRestriction[complete]
-
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.sum_deltaRandomSubsetWeight_mem (n : ℕ) (δ : ℝ) (i : Fin n) : (∑ J, if i ∈ J then FABL.deltaRandomSubsetWeight n δ J else 0) = δ
theorem FABL.sum_deltaRandomSubsetWeight_mem (n : ℕ) (δ : ℝ) (i : Fin n) : (∑ J, if i ∈ J then FABL.deltaRandomSubsetWeight n δ J else 0) = δ
Weight of free sets containing a fixed coordinate equals `δ`.
-
defdefined in FABL/Chapter04/RandomRestrictions.leancomplete
def FABL.freePart {n : ℕ} (J : Finset (Fin n)) (x : FABL.SignCube n) : FABL.FreeSignCube J
def FABL.freePart {n : ℕ} (J : Finset (Fin n)) (x : FABL.SignCube n) : FABL.FreeSignCube J
Free assignment extracted from a full cube string.
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.discreteDerivative_extendedSignRestriction_of_mem {n : ℕ} (f : FABL.SignCube n → ℝ) (J : Finset (Fin n)) (z : FABL.FixedSignCube J) (i : Fin n) (hi : i ∈ J) (x : FABL.SignCube n) : (FABL.discreteDerivative i) (FABL.extendedSignRestriction f J z) x = (FABL.discreteDerivative i) f (FABL.combineSignCube J (fun j => x ↑j) z)
theorem FABL.discreteDerivative_extendedSignRestriction_of_mem {n : ℕ} (f : FABL.SignCube n → ℝ) (J : Finset (Fin n)) (z : FABL.FixedSignCube J) (i : Fin n) (hi : i ∈ J) (x : FABL.SignCube n) : (FABL.discreteDerivative i) (FABL.extendedSignRestriction f J z) x = (FABL.discreteDerivative i) f (FABL.combineSignCube J (fun j => x ↑j) z)
Free-coordinate discrete derivative of an extension equals that of `f`.
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.expect_sq_discreteDerivative_combine {n : ℕ} (f : FABL.SignCube n → ℝ) (J : Finset (Fin n)) (i : Fin n) (z : FABL.FixedSignCube J) : (Finset.univ.expect fun x => (FABL.discreteDerivative i) f (FABL.combineSignCube J (FABL.freePart J x) z) ^ 2) = Finset.univ.expect fun y => (FABL.discreteDerivative i) f (FABL.combineSignCube J y z) ^ 2
theorem FABL.expect_sq_discreteDerivative_combine {n : ℕ} (f : FABL.SignCube n → ℝ) (J : Finset (Fin n)) (i : Fin n) (z : FABL.FixedSignCube J) : (Finset.univ.expect fun x => (FABL.discreteDerivative i) f (FABL.combineSignCube J (FABL.freePart J x) z) ^ 2) = Finset.univ.expect fun y => (FABL.discreteDerivative i) f (FABL.combineSignCube J y z) ^ 2
Averaging a squared discrete derivative that depends only on free coordinates.
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.expect_sq_discreteDerivative_product {n : ℕ} (f : FABL.SignCube n → ℝ) (J : Finset (Fin n)) (i : Fin n) : (Finset.univ.expect fun y => Finset.univ.expect fun z => (FABL.discreteDerivative i) f (FABL.combineSignCube J y z) ^ 2) = FABL.influence f i
theorem FABL.expect_sq_discreteDerivative_product {n : ℕ} (f : FABL.SignCube n → ℝ) (J : Finset (Fin n)) (i : Fin n) : (Finset.univ.expect fun y => Finset.univ.expect fun z => (FABL.discreteDerivative i) f (FABL.combineSignCube J y z) ^ 2) = FABL.influence f i
Free/fixed product measure recovers ambient influence.
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.expect_influence_extendedSignRestriction_of_mem {n : ℕ} (f : FABL.SignCube n → ℝ) (J : Finset (Fin n)) (i : Fin n) (hi : i ∈ J) : (Finset.univ.expect fun z => FABL.influence (FABL.extendedSignRestriction f J z) i) = FABL.influence f i
theorem FABL.expect_influence_extendedSignRestriction_of_mem {n : ℕ} (f : FABL.SignCube n → ℝ) (J : Finset (Fin n)) (i : Fin n) (hi : i ∈ J) : (Finset.univ.expect fun z => FABL.influence (FABL.extendedSignRestriction f J z) i) = FABL.influence f i
Conditional expected influence equals original when the coordinate is free.
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.expect_influence_extended_randomRestriction {n : ℕ} (f : FABL.SignCube n → ℝ) (δ : ℝ) (i : Fin n) : (FABL.expectRandomRestriction n δ fun J z => FABL.influence (FABL.extendedSignRestriction f J z) i) = δ * FABL.influence f i
theorem FABL.expect_influence_extended_randomRestriction {n : ℕ} (f : FABL.SignCube n → ℝ) (δ : ℝ) (i : Fin n) : (FABL.expectRandomRestriction n δ fun J z => FABL.influence (FABL.extendedSignRestriction f J z) i) = δ * FABL.influence f i
O'Donnell, Corollary 4.18.
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.expect_totalInfluence_extended_randomRestriction {n : ℕ} (f : FABL.SignCube n → ℝ) (δ : ℝ) : (FABL.expectRandomRestriction n δ fun J z => FABL.totalInfluence (FABL.extendedSignRestriction f J z)) = δ * FABL.totalInfluence f
theorem FABL.expect_totalInfluence_extended_randomRestriction {n : ℕ} (f : FABL.SignCube n → ℝ) (δ : ℝ) : (FABL.expectRandomRestriction n δ fun J z => FABL.totalInfluence (FABL.extendedSignRestriction f J z)) = δ * FABL.totalInfluence f
O'Donnell, Corollary 4.18 for total influence.
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FABL.literal_not_falsified_local_weight[complete] -
FABL.DNFTerm.notFalsified[complete] -
FABL.term_not_falsified_weight[complete] -
FABL.restrictedWidth_ge_probability_le[complete]
Lemma 4.19. Let T be a DNF term over \{-1,1\}^n and fix
w\in\mathbb N^+. Let (\boldsymbol J\mid\boldsymbol z) be a
(1/2)-random restriction on \{-1,1\}^n. Then
\Pr\bigl[\operatorname{width}(T_{\boldsymbol J\mid\boldsymbol z})\ge w\bigr]
\le\Bigl(\frac34\Bigr)^w.
Under the half-random restriction, each coordinate is free with probability
1/2 and fixed to either sign with probability 1/4. Thus a term is not
falsified with probability (3/4)^{\operatorname{width}(T)}, which gives
the tail bound.
Lean code for Lemma4.3.5●4 declarations
Associated Lean declarations
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FABL.literal_not_falsified_local_weight[complete]
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FABL.DNFTerm.notFalsified[complete]
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FABL.term_not_falsified_weight[complete]
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FABL.restrictedWidth_ge_probability_le[complete]
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FABL.literal_not_falsified_local_weight[complete] -
FABL.DNFTerm.notFalsified[complete] -
FABL.term_not_falsified_weight[complete] -
FABL.restrictedWidth_ge_probability_le[complete]
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.literal_not_falsified_local_weight {n : ℕ} (ℓ : FABL.Literal n) : (∑ c, FABL.coordRestrictionWeight c * if (ℓ.isFalsified fun x => c) = true then 0 else 1) = 3 / 4
theorem FABL.literal_not_falsified_local_weight {n : ℕ} (ℓ : FABL.Literal n) : (∑ c, FABL.coordRestrictionWeight c * if (ℓ.isFalsified fun x => c) = true then 0 else 1) = 3 / 4
Local weight that a literal is not fixed to False is `3/4`.
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defdefined in FABL/Chapter04/RandomRestrictions.leancomplete
def FABL.DNFTerm.notFalsified {n : ℕ} (T : FABL.DNFTerm n) (ρ : Fin n → FABL.CoordRestriction) : Bool
def FABL.DNFTerm.notFalsified {n : ℕ} (T : FABL.DNFTerm n) (ρ : Fin n → FABL.CoordRestriction) : Bool
Indicator that no literal of a term is falsified.
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.term_not_falsified_weight {n : ℕ} (T : FABL.DNFTerm n) : (∑ ρ, FABL.restrictionAssignmentWeight ρ * if T.notFalsified ρ = true then 1 else 0) = (3 / 4) ^ T.width
theorem FABL.term_not_falsified_weight {n : ℕ} (T : FABL.DNFTerm n) : (∑ ρ, FABL.restrictionAssignmentWeight ρ * if T.notFalsified ρ = true then 1 else 0) = (3 / 4) ^ T.width
Weight that a term is not falsified equals `(3/4)^{width}`. -
theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.restrictedWidth_ge_probability_le {n : ℕ} (T : FABL.DNFTerm n) (w : ℕ) : (∑ ρ, FABL.restrictionAssignmentWeight ρ * if w ≤ T.restrictedWidthOf ρ then 1 else 0) ≤ (3 / 4) ^ w
theorem FABL.restrictedWidth_ge_probability_le {n : ℕ} (T : FABL.DNFTerm n) (w : ℕ) : (∑ ρ, FABL.restrictionAssignmentWeight ρ * if w ≤ T.restrictedWidthOf ρ then 1 else 0) ≤ (3 / 4) ^ w
O'Donnell, Lemma 4.19.
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FABL.sum_inverse_two_pow_succ_Ico_le[complete] -
FABL.DNFFormula.selectedTerm[complete] -
FABL.DNFFormula.selectedWidth[complete] -
FABL.DNFFormula.selectedTerm_mem[complete] -
FABL.DNFFormula.selectedTerm_eval[complete] -
FABL.DNFFormula.selectedWidth_eq_zero_of_eval_ne[complete] -
FABL.DNFFormula.selectedWidth_le_dimension[complete] -
FABL.card_negOnePivotal_le_selectedWidth[complete] -
FABL.selectedWidth_tail_probability_le[complete] -
FABL.uniformProbability_le_one[complete] -
FABL.expect_selectedWidth_eq_sum_tail[complete] -
FABL.expect_selectedWidth_le_clog_add_one[complete] -
FABL.totalInfluence_le_two_mul_clog_add_one_of_hasDNFSizeLE[complete]
Theorem 4.20. Let f:\{-1,1\}^n\to\{-1,1\} be computable by a DNF of size
s. Then \mathbf I[f]\le O(\log s).
More precisely,
\mathbf I[f]\le 2\bigl(\lceil\log_2 s\rceil+1\bigr),
which implies the stated O(\log s) claim. Select one satisfied
term on every true input, bound the number of negative pivotal coordinates by that
term's width, prove the tail estimate
\Pr[\operatorname{width}\ge k]\le s2^{-k}, and sum the tails.
Lean code for Theorem4.3.6●13 declarations
Associated Lean declarations
-
FABL.sum_inverse_two_pow_succ_Ico_le[complete]
-
FABL.DNFFormula.selectedTerm[complete]
-
FABL.DNFFormula.selectedWidth[complete]
-
FABL.DNFFormula.selectedTerm_mem[complete]
-
FABL.DNFFormula.selectedTerm_eval[complete]
-
FABL.DNFFormula.selectedWidth_eq_zero_of_eval_ne[complete]
-
FABL.DNFFormula.selectedWidth_le_dimension[complete]
-
FABL.card_negOnePivotal_le_selectedWidth[complete]
-
FABL.selectedWidth_tail_probability_le[complete]
-
FABL.uniformProbability_le_one[complete]
-
FABL.expect_selectedWidth_eq_sum_tail[complete]
-
FABL.expect_selectedWidth_le_clog_add_one[complete]
-
FABL.totalInfluence_le_two_mul_clog_add_one_of_hasDNFSizeLE[complete]
-
FABL.sum_inverse_two_pow_succ_Ico_le[complete] -
FABL.DNFFormula.selectedTerm[complete] -
FABL.DNFFormula.selectedWidth[complete] -
FABL.DNFFormula.selectedTerm_mem[complete] -
FABL.DNFFormula.selectedTerm_eval[complete] -
FABL.DNFFormula.selectedWidth_eq_zero_of_eval_ne[complete] -
FABL.DNFFormula.selectedWidth_le_dimension[complete] -
FABL.card_negOnePivotal_le_selectedWidth[complete] -
FABL.selectedWidth_tail_probability_le[complete] -
FABL.uniformProbability_le_one[complete] -
FABL.expect_selectedWidth_eq_sum_tail[complete] -
FABL.expect_selectedWidth_le_clog_add_one[complete] -
FABL.totalInfluence_le_two_mul_clog_add_one_of_hasDNFSizeLE[complete]
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.sum_inverse_two_pow_succ_Ico_le (m n : ℕ) : ∑ k ∈ Finset.Ico m n, (2 ^ (k + 1))⁻¹ ≤ (2 ^ m)⁻¹
theorem FABL.sum_inverse_two_pow_succ_Ico_le (m n : ℕ) : ∑ k ∈ Finset.Ico m n, (2 ^ (k + 1))⁻¹ ≤ (2 ^ m)⁻¹
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defdefined in FABL/Chapter04/RandomRestrictions.leancomplete
def FABL.DNFFormula.selectedTerm {n : ℕ} (φ : FABL.DNFFormula n) (x : FABL.SignCube n) : FABL.DNFTerm n
def FABL.DNFFormula.selectedTerm {n : ℕ} (φ : FABL.DNFFormula n) (x : FABL.SignCube n) : FABL.DNFTerm n
A canonical satisfied term, with the empty term used when the DNF evaluates to `1`.
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defdefined in FABL/Chapter04/RandomRestrictions.leancomplete
def FABL.DNFFormula.selectedWidth {n : ℕ} (φ : FABL.DNFFormula n) (x : FABL.SignCube n) : ℕ
def FABL.DNFFormula.selectedWidth {n : ℕ} (φ : FABL.DNFFormula n) (x : FABL.SignCube n) : ℕ
Width of the selected satisfied term.
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.DNFFormula.selectedTerm_mem {n : ℕ} (φ : FABL.DNFFormula n) (x : FABL.SignCube n) (hx : φ.eval x = -1) : φ.selectedTerm x ∈ φ.terms
theorem FABL.DNFFormula.selectedTerm_mem {n : ℕ} (φ : FABL.DNFFormula n) (x : FABL.SignCube n) (hx : φ.eval x = -1) : φ.selectedTerm x ∈ φ.terms
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.DNFFormula.selectedTerm_eval {n : ℕ} (φ : FABL.DNFFormula n) (x : FABL.SignCube n) (hx : φ.eval x = -1) : (φ.selectedTerm x).eval x = -1
theorem FABL.DNFFormula.selectedTerm_eval {n : ℕ} (φ : FABL.DNFFormula n) (x : FABL.SignCube n) (hx : φ.eval x = -1) : (φ.selectedTerm x).eval x = -1
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.DNFFormula.selectedWidth_eq_zero_of_eval_ne {n : ℕ} (φ : FABL.DNFFormula n) (x : FABL.SignCube n) (hx : φ.eval x ≠ -1) : φ.selectedWidth x = 0
theorem FABL.DNFFormula.selectedWidth_eq_zero_of_eval_ne {n : ℕ} (φ : FABL.DNFFormula n) (x : FABL.SignCube n) (hx : φ.eval x ≠ -1) : φ.selectedWidth x = 0
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.DNFFormula.selectedWidth_le_dimension {n : ℕ} (φ : FABL.DNFFormula n) (x : FABL.SignCube n) : φ.selectedWidth x ≤ n
theorem FABL.DNFFormula.selectedWidth_le_dimension {n : ℕ} (φ : FABL.DNFFormula n) (x : FABL.SignCube n) : φ.selectedWidth x ≤ n
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.card_negOnePivotal_le_selectedWidth {n : ℕ} (φ : FABL.DNFFormula n) (x : FABL.SignCube n) : {i | FABL.IsNegOnePivotal φ.toBooleanFunction i x}.card ≤ φ.selectedWidth x
theorem FABL.card_negOnePivotal_le_selectedWidth {n : ℕ} (φ : FABL.DNFFormula n) (x : FABL.SignCube n) : {i | FABL.IsNegOnePivotal φ.toBooleanFunction i x}.card ≤ φ.selectedWidth x
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.selectedWidth_tail_probability_le {n : ℕ} (φ : FABL.DNFFormula n) (k : ℕ) (hk : 0 < k) : (FABL.uniformProbability fun x => k ≤ φ.selectedWidth x) ≤ ↑φ.size * (2 ^ k)⁻¹
theorem FABL.selectedWidth_tail_probability_le {n : ℕ} (φ : FABL.DNFFormula n) (k : ℕ) (hk : 0 < k) : (FABL.uniformProbability fun x => k ≤ φ.selectedWidth x) ≤ ↑φ.size * (2 ^ k)⁻¹
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.uniformProbability_le_one.{u_1} {Ω : Type u_1} [Fintype Ω] [Nonempty Ω] (P : Ω → Prop) [DecidablePred P] : FABL.uniformProbability P ≤ 1
theorem FABL.uniformProbability_le_one.{u_1} {Ω : Type u_1} [Fintype Ω] [Nonempty Ω] (P : Ω → Prop) [DecidablePred P] : FABL.uniformProbability P ≤ 1
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.expect_selectedWidth_eq_sum_tail {n : ℕ} (φ : FABL.DNFFormula n) : (Finset.univ.expect fun x => ↑(φ.selectedWidth x)) = ∑ k ∈ Finset.range n, FABL.uniformProbability fun x => k + 1 ≤ φ.selectedWidth x
theorem FABL.expect_selectedWidth_eq_sum_tail {n : ℕ} (φ : FABL.DNFFormula n) : (Finset.univ.expect fun x => ↑(φ.selectedWidth x)) = ∑ k ∈ Finset.range n, FABL.uniformProbability fun x => k + 1 ≤ φ.selectedWidth x
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.expect_selectedWidth_le_clog_add_one {n : ℕ} (φ : FABL.DNFFormula n) {s : ℕ} (hsize : φ.size ≤ s) : (Finset.univ.expect fun x => ↑(φ.selectedWidth x)) ≤ ↑(Nat.clog 2 s) + 1
theorem FABL.expect_selectedWidth_le_clog_add_one {n : ℕ} (φ : FABL.DNFFormula n) {s : ℕ} (hsize : φ.size ≤ s) : (Finset.univ.expect fun x => ↑(φ.selectedWidth x)) ≤ ↑(Nat.clog 2 s) + 1
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theoremdefined in FABL/Chapter04/RandomRestrictions.leancomplete
theorem FABL.totalInfluence_le_two_mul_clog_add_one_of_hasDNFSizeLE {n : ℕ} {f : FABL.BooleanFunction n} {s : ℕ} (hf : FABL.HasDNFSizeLE f s) : FABL.totalInfluence f.toReal ≤ 2 * (↑(Nat.clog 2 s) + 1)
theorem FABL.totalInfluence_le_two_mul_clog_add_one_of_hasDNFSizeLE {n : ℕ} {f : FABL.BooleanFunction n} {s : ℕ} (hf : FABL.HasDNFSizeLE f s) : FABL.totalInfluence f.toReal ≤ 2 * (↑(Nat.clog 2 s) + 1)
O'Donnell, Theorem 4.20, with an explicit logarithmic bound.