Replacement designs and algebraic assembly for the shared-summary counting routine #
Section 3 of OpenAI, The Exponential Time Hypothesis is False evaluates a finite
sum of products of polynomial factors on the Boolean cube,
$$Z = \sum_{x \in \{0, 1\}^n} \prod_{f \in F} \Phi_f((x_v)_{v \in I_f}),$$
over any commutative ℚ-algebra A by embedding Z as H(0) for a low-degree univariate
polynomial H(T) ∈ A[T] built from polynomial replacement rows P⃗_{f,v}(T).
This module provides the algebraic design interface, domain cardinality bounds, and assembly
identities from §§3.1–3.3 and §3.5 (Definition 3.1, Lemma 3.2, Proposition 3.4, and equations
(3.1)–(3.6), (3.11)–(3.15), pp. 21–26), leaving the §3.4 affine/Taylor expansion (equations
(3.7)–(3.10)) to AffineTaylor, the fixed-denominator coefficient bit-length condition
(Definition 3.1(5)) to staged jet arithmetic, and Turing-machine time/space bounds to the runtime
layer.
Main definitions #
Cslib.ReplacementCounting.intMeasurementBox: integer summary box[-D, D]^cof size(2D+1)^c.Cslib.ReplacementCounting.piGroupEquiv: decomposition(∀ g, {i // group i = g} → α) ≃ (ι → α).Cslib.ReplacementCounting.Design: algebraic(r, τ, D)-replacement design (Def. 3.1(1)–(4)).Cslib.ReplacementCounting.targetSum,Cslib.ReplacementCounting.liftedFactorProduct,Cslib.ReplacementCounting.targetPolynomial:Z(eq. (3.1)), disjoint-incidence product (eq. (3.2)), andH(T)(eq. (3.3)).Cslib.ReplacementCounting.jetOrder: confluent Taylor jet orderJ = ⌊d_H / Q⌋ + 1(eq. (3.5)).
Main results #
Cslib.ReplacementCounting.pow_mul_subsetPairCount_le,Cslib.ReplacementCounting.subsetPairCount_le_one_div_pow_mul,Cslib.ReplacementCounting.subsetPairCount_le_ratio_pow: weightedCslib.subsetPairCountbounds (eq. (3.15)).Cslib.ReplacementCounting.boolean_mulVec_mem_intMeasurementBox,Cslib.ReplacementCounting.card_intMeasurementBox: Boolean measurement inclusion and box size.Cslib.ReplacementCounting.Design.evalRow_eq_of_same_measurements: kernel shifts imply fiber locality viaCslib.SharedSummaries.fiber_locality_of_kernel_shifts.Cslib.ReplacementCounting.eval_zero_targetPolynomial,Cslib.ReplacementCounting.natDegree_targetPolynomial_le_of_liftedTotalDegree_le:H(0) = Zand degree bound≤ d * d₀.Cslib.ReplacementCounting.Design.sum_restricted_prod_eq_sum_measurement_fibers: restricted-slice factorization viaCslib.SharedSummaries.sum_prod_eq_sum_measurement_fibers(Lemma 3.2 and equations (3.11), (3.13)).Cslib.ReplacementCounting.targetSum_eq_of_taylorJet,Cslib.ReplacementCounting.Design.targetSum_eq_of_taylorJet: exact recovery ofZfrom confluent Taylor jets viaPolynomial.eval_zero_eq_of_taylorJet.Cslib.ReplacementCounting.Design.domainExaminationBound_real:2 Q r C_q (2D+1)^{2τn} 2^{2n/r}bound across nodes, subset pairs, and measurement boxes (eq. (3.12) and Proposition 3.4).
References #
- OpenAI, The Exponential Time Hypothesis is False, §§3.1–3.3 and §3.5, Definition 3.1, Lemma 3.2, Proposition 3.4, pp. 21–26.
1. Subset-pair count and weighted binomial bound (equations (3.14)–(3.15)) #
Specialization of subsetPairCount_le_one_div_pow_mul to η = R / Q for 1 ≤ R ≤ Q
([OAI26c], p. 26): C_q ≤ (Q / R) ^ q * (1 + 2 * (R / Q)) ^ n.
2. Integer measurement boxes and group decompositions #
[-D, D] ∩ ℤ has cardinality 2 * D + 1.
intMeasurementBox D c has cardinality (2 * D + 1) ^ c.
Applying a c-row integer matrix whose rows have ℓ₁-norm at most D to a Boolean vector
lands inside intMeasurementBox D c.
The image of the Boolean cube α → Bool under a c-row integer matrix of row ℓ₁-norm at
most D is contained in intMeasurementBox D c and has cardinality at most (2 * D + 1) ^ c.
Canonical decomposition of functions on ι into functions on the fibers of group : ι → G,
specializing (Equiv.piCongrFiberwise fun _ => Equiv.refl _).symm.
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3. Definition 3.1 (r, τ, D)-replacement design interface #
Algebraic (r, τ, D)-replacement design at Q distinct nonzero integer evaluation nodes for a
finite family of factors s : Finset F with variable scopes scope : ∀ f, κ f → ι
([OAI26c], Definition 3.1(1)–(4), pp. 21–22).
Condition (5) of Definition 3.1 (the integer bit-length bound after clearing (R - 1)! Q!) is a
staging property for exact fixed-denominator arithmetic in Appendix B and is kept separate from this
algebraic interface.
Number of variable groups satisfies
2 ≤ r.Row
ℓ₁-bound satisfies1 ≤ D.Replacement degree bound satisfies
1 ≤ R.Number of evaluation nodes satisfies
R < Q.Total measurement-row density parameter satisfies
0 < τ.Total measurement-row density parameter satisfies
τ ≤ 1 / 2.Evaluation nodes in
ℤ(in the paper1, …, Q), pairwise distinct and nonzero.- nodes_injective : Function.Injective self.nodes
Partition
[n] = S_{t,1} ⊔ ⋯ ⊔ S_{t,r}at nodet, encoded byi ↦ g.- card_varGroup_le (t : Fin Q) (g : Fin r) : {i : ι | self.varGroup t i = g}.card * r ≤ 2 * Fintype.card ι
Group size bound
|S_{t,g}| ≤ 2n / r, stated multiplicatively as|S_{t,g}| * r ≤ 2 * n. Assigned group
σ_f(t) ∈ [r]of factorfat nodet.Number of integer measurement rows
c_{t,g}on groupgat nodet.Total measurement row bound
∑_g c_{t,g} ≤ 2 τ n.Integer measurement matrices
C_{t,g}, indexed onιand supported onS_{t,g}.- row_l1_le (t : Fin Q) (g : Fin r) (k : Fin (self.numRows t g)) : ∑ i : ι, (self.matrix t g k i).natAbs ≤ D
Every row of
C_{t,g}has sum of absolute values at mostD. - row (f : F) : κ f → ι → Polynomial ℚ
Polynomial replacement rows
P⃗_{f,v}(T) ∈ ℚ[T]^{1 × n}. - row_eval_zero (f : F) : f ∈ s → ∀ (v : κ f) (i : ι), Polynomial.eval 0 (self.row f v i) = if i = scope f v then 1 else 0
At
T = 0,P⃗_{f,v}(0) = δ_{scope f v}. Each replacement entry has univariate degree at most
R.- kernel_zero (t : Fin Q) (f : F) : f ∈ s → ∀ (v : κ f) (g : Fin r), g ≠ self.factorGroup f t → ∀ (ξ : ι → ℚ), (∀ (i : ι), self.varGroup t i ≠ g → ξ i = 0) → (∀ (k : Fin (self.numRows t g)), ∑ i : ι, ↑(self.matrix t g k i) * ξ i = 0) → ∑ i : ι, Polynomial.eval (↑(self.nodes t)) (self.row f v i) * ξ i = 0
Kernel condition (Definition 3.1(4)): for
g ≠ σ_f(t)andξsupported onS_{t,g},C_{t,g} ξ = 0implies⟨P⃗_{f,v}(nodes t), ξ⟩ = 0.
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Variables belonging to group g at node t (S_{t,g}).
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The group sets S_{t,g} partition Finset.univ.
Distinct groups at node t are disjoint.
Natural-division form of the group size bound: #S_{t,g} ≤ (2 * n) / r.
Real-division form of the group size bound: (#S_{t,g} : ℝ) ≤ 2 * n / r.
Type of local Boolean assignments on group g at node t ({0, 1}^{S_{t,g}}).
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Cardinality of the local Boolean cube on group g at node t is 2 ^ #S_{t,g}.
Local integer measurement of u ∈ {0, 1}^{S_{t,g}} under C_{t,g}.
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Global integer measurement of x : ι → Bool on group g at node t.
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Because C_{t,g} is supported on S_{t,g}, the global measurement of a glued assignment
agrees with the local measurement on group g.
Per-group measurement box [-D, D]^{c_{t,g}} at node t.
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Full measurement tuple box ∏_g [-D, D]^{c_{t,g}} at node t.
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Every local Boolean assignment on group g has its measurement in M.groupBox t g.
Exact cardinality (2 * D + 1) ^ (∑_g c_{t,g}) of M.measurementBox t
([OAI26c], p. 23).
Real-exponent bound (#(M.measurementBox t) : ℝ) ≤ (2D + 1) ^ (2 τ n) from
∑_g c_{t,g} ≤ 2 τ n ([OAI26c], equation (3.12), p. 25).
Evaluation of the rational replacement linear form ⟨P⃗_{f,v}(nodes t), x⟩ on x : ι → ℚ.
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Evaluation of the rational replacement linear form ⟨P⃗_{f,v}(nodes t), x⟩ on a Boolean
assignment x : ι → Bool.
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Single-group invariance ([OAI26c], p. 22): if x, x' : ι → ℚ agree outside S_{t,h} for
some h ≠ σ_f(t) and have equal C_{t,h} measurements, then ⟨P⃗_{f,v}(nodes t), x⟩ = ⟨P⃗_{f,v}(nodes t), x'⟩.
All-groups rational invariance ([OAI26c], p. 22), derived via
Cslib.SharedSummaries.fiber_locality_of_kernel_shifts: if x, x' : ι → ℚ agree on the assigned
group S_{t,σ_f(t)} and have equal C_{t,h} measurements on all other groups h ≠ σ_f(t), then
⟨P⃗_{f,v}(nodes t), x⟩ = ⟨P⃗_{f,v}(nodes t), x'⟩.
Boolean fiber-locality of evalRow: if two grouped Boolean assignments u, u' have the same
integer measurements on every group and agree on σ_f(t), then evalRow agrees on their glued
Boolean assignments.
Replacement rows mapped into any commutative ℚ-algebra A.
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4. Target sum Z, univariate polynomial H(T), and degree bounds (§3.1, eqs. 3.1–3.3) #
The target Boolean-cube sum Z = ∑_{x ∈ {0, 1}^n} ∏_{f ∈ s} Φ_f((x_v)_{v ∈ I_f})
([OAI26c], equation (3.1), p. 21).
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Disjoint-incidence product polynomial ∏_{f ∈ s} Φ_f((Y_{f,v})_{v ∈ κ f}) in
MvPolynomial (Σ f, κ f) A, whose totalDegree is bounded by d in equation (3.2) of
[OAI26c] (p. 21).
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The disjoint-incidence product has total degree at most ∑_{f ∈ s} (Φ f).totalDegree.
Linear replacement form ⟨P⃗_{f,v}(T), x⟩ = ∑_i P_{f,v,i}(T) x_i in Polynomial A.
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Target univariate polynomial H(T) = ∑_{x ∈ {0,1}^n} ∏_{f ∈ s} Φ_f(⟨P⃗_{f,v}(T), x⟩) in
Polynomial A ([OAI26c], equation (3.3), p. 21).
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Evaluating targetPolynomial at a scalar t : A evaluates every replacement row at t.
At T = 0, H(0) = Z ([OAI26c], equations (3.1) and (3.3), p. 21): when every
replacement row restores δ_{scope f v} at T = 0, (targetPolynomial s Φ P).eval 0 equals
targetSum s scope Φ.
Substituting univariate polynomials of degree at most d₀ into a multivariate polynomial p
gives a univariate polynomial of natDegree at most p.totalDegree * d₀.
Degree bound for H(T) from the lifted product degree ([OAI26c], equations
(3.2)–(3.3), p. 21): if liftedFactorProduct s Φ has total degree at most d and active
replacement rows have natDegree at most d₀, then (targetPolynomial s Φ P).natDegree ≤ d * d₀.
Sum-of-degrees bound for H(T): if active replacement rows have natDegree at most d₀,
then (targetPolynomial s Φ P).natDegree ≤ (∑_{f ∈ s} (Φ f).totalDegree) * d₀.
Specialization to degree-≤ R - 1 replacement rows (as constructed in Section 4 of
[OAI26c]): (targetPolynomial s Φ P).natDegree ≤ d * (R - 1) and ≤ d * R.
5. Jet order and generic Hermite recovery of Z = H(0) (equations (3.5)–(3.6)) #
Confluent Taylor jet order J = ⌊d_H / Q⌋ + 1 ([OAI26c], equation (3.5), p. 24).
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Exact Z = H(0) recovery from confluent Taylor jets ([OAI26c], §3.4, p. 24):
given N injective integer nodes (0 < N), jet order 0 < J, and replacement rows over a
commutative ℚ-algebra A restoring scope at T = 0 such that
(targetPolynomial s Φ P).natDegree < N * J, targetSum s scope Φ is recovered directly from
Polynomial.taylorJet via Polynomial.eval_zero_eq_of_taylorJet.
Restricted local Boolean cube X_{g, E} on group g at node t, fixing u_i = true for
i ∈ E ∩ S_{t,g} ([OAI26c], Lemma 3.2 proof, p. 23).
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Product of factors assigned to group g at node t when each factor f is evaluated on its
baseline vector v ↦ M.evalRow t f v x ([OAI26c], equation (3.11), p. 25).
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Grouping factors by σ_f(t) preserves the full product over s ([OAI26c],
equation (3.11), p. 25).
groupedFactor depends on u only through u g and the integer measurements of all groups.
Restricted-slice measurement-fiber factorization ([OAI26c], Lemma 3.2 and equations
(3.11), (3.13), pp. 22–25): for any subset E ⊆ ι, ring B, evaluator evalFactor, and valid
unrestricted fiber representative selector, the sum over {x : ι → Bool | ∀ i ∈ E, x i = true}
factors into per-group sums over M.measurementBox t via
Cslib.SharedSummaries.sum_prod_eq_sum_measurement_fibers.
Target polynomial H(T) ∈ A[T] instantiated with M.rowIn A.
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At T = 0, (M.targetPoly Φ).eval 0 = targetSum s scope Φ.
Degree bound (M.targetPoly Φ).natDegree ≤ d * R when (liftedFactorProduct s Φ).totalDegree ≤ d ([OAI26c], equations (3.2)–(3.3), p. 21).
Unrestricted node evaluation H(nodes t) via measurement fibers ([OAI26c], §3.3,
p. 23): evaluating M.targetPoly Φ at M.nodes t equals the E = ∅ measurement-fiber sum over
M.measurementBox t.
Factor Φ_{f, U}(x; z) ∈ Polynomial A at node t after fixing X⃗ = 1_U in the Taylor
correction ([OAI26c], equations (3.8) and (3.11), pp. 24–25).
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Specialization of sum_restricted_prod_eq_sum_measurement_fibers to the Taylor-shifted factors
Φ_{f, U}(x; z) in Polynomial A ([OAI26c], equations (3.11) and (3.13), p. 25).
Hermite jet recovery of Z for a Design ([OAI26c], equations (3.5)–(3.6) and
Proposition 3.4, pp. 24–25): whenever (liftedFactorProduct s Φ).totalDegree ≤ d and d * R < Q * J (in particular for J = jetOrder (d * R) Q), targetSum s scope Φ equals the Hermite
determinant expression in the order-J Taylor jets of M.targetPoly Φ at M.nodes.
Specialization of Design.targetSum_eq_of_taylorJet at the canonical jet order
J = jetOrder (d * R) Q = ⌊d * R / Q⌋ + 1 ([OAI26c], equation (3.5), p. 24).
Exact natural-number two-pass local-cube scan count
2 (2D + 1) ^ (∑_g c_{t,g}) ∑_g 2 ^ |S_{t,g}| at node t ([OAI26c], Lemma 3.2, p. 22).
Sum of local Boolean cube cardinalities across all r groups at node t is at most
r * 2 ^ ((2 * n) / r).
Per-pair Boolean-vector scan bound at node t ([OAI26c], equation (3.12), p. 25):
two scans of all r local cubes across every tuple in M.measurementBox t inspect at most
2 * r * (2D + 1) ^ (2 τ n) * 2 ^ (2 n / r) local assignments.
Total finite-domain examination bound across all Q nodes and C_q subset pairs
([OAI26c], Proposition 3.4, p. 25): summing the two-pass local-cube scan count over all
t : Fin Q and all subset pairs (E, U) with #E ≤ q and U ⊆ E yields at most
2 Q r C_q (2D + 1) ^ (2 τ n) 2 ^ (2 n / r).