A proof of the strong Gaussian product inequality conjecture

Frédéric Ouimet, Dylan Greaves

For any centered Gaussian vector, including singular covariance, and positive real exponents αᵢ, the expected product of |Xᵢ|^αᵢ is at least the product of the corresponding marginal expectations.

Sources for this record

What was already known

The conjecture was known in restricted dimensions, exponent ranges or covariance classes; the general positive-exponent case remained open.

AI involvement AI-led

Greaves credits ChatGPT 5.6 Sol with the early complete proof. Greaves formalized it with Codex; Ouimet rewrote the exposition and added separate equality results.

A specific, complete early proof of the central inequality is expressly attributed to ChatGPT 5.6 Sol; Greaves supplied the prompt and the later authors reworked it.

Importance Notable

Proves the general strong Gaussian product inequality.

Limitations

The reported Lean theorem checks the main inequality, not Ouimet’s later equality characterization. The published record reports the Lean build; an independent replay is not documented.

Technical verification Formal (Lean 4 with Mathlib; project lake build)

The authors report a Lean formalization of the early inequality proof, and its repository names a complete main theorem and build. This covers the positive-exponent inequality, not Ouimet’s later equality characterization; the build was not independently replayed here.

Independent checking

complete Lean main theorem GaussianProduct.gaussian_product_inequality and project build

Checker
Lean through Greaves’s Codex-assisted GaussianProduct project
Scope
positive-exponent Gaussian product inequality for centered Gaussian vectors
Basis
Reported by the linked checker
Evidence source

Human understanding Full

Ouimet reworked the proof and the paper explains the branch-averaging kernel inequality and integral recovery of moments; the equality analysis is credited to him separately.

Correction and publication history

2026-10-18 · publication

The assessed result is the main positive-exponent inequality; equality conditions retain separate credit.

Read this published revision