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Partial differential equations · Result 367

The critical dimension for the one-phase Bernoulli problem

1 paperLean

Establishes seven as the first dimension admitting a nonflat, one-homogeneous global minimizer of the one-phase Bernoulli energy. Consequently, minimizing free boundaries are smooth through dimension six, and their singular sets have dimension at most \(n-7\) in higher dimensions.

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▶Introduction: the problem and why it mattersin preparation
▶The presented solutionin preparation

Papers 1

First page of The critical dimension for one-phase Bernoulli minimizers

The critical dimension for one-phase Bernoulli minimizers

OpenAI · September 24, 2026

We prove that seven is the critical dimension for the one-phase Bernoulli problem: every nonzero one-homogeneous global minimizer in dimensions at most six is flat, while a nonflat one-homogeneous global minimizer exists in dimension seven. It follows that the interior free boundary of a local minimizer is smooth in dimensions at most six. In dimension n ≥ 7, its singular set has Hausdorff dimension at most \(n-7\), and this bound is sharp. In dimension seven, the singular set is locally finite.

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@misc{OAI:The-critical-dimension-for-one-phase-Bernoulli-minimizers-September-24-2026,
  author = {{OpenAI}},
  title = {{The critical dimension for one-phase Bernoulli minimizers}},
  howpublished = {OpenAI Math Release preprint
                  \href{https://github.com/openai/math/blob/main/preprints/The-critical-dimension-for-one-phase-Bernoulli-minimizers-September-24-2026/The-critical-dimension-for-one-phase-Bernoulli-minimizers-September-24-2026.pdf}{OAI:The-critical-dimension-for-one-phase-Bernoulli-minimizers-September-24-2026}},
  year = {2026}
}

What was formalized in Lean

The following describes the scope of the Lean formalization related to the following accompanying paper(s):

Scope

The paper identifies seven as the critical dimension for nonflat one-homogeneous global minimizers of the one-phase Bernoulli problem. The linked formalization proves the existence side: in dimension seven there is a nonzero one-homogeneous global minimizer that is not a half-space solution.

The flatness classification in dimensions at most six and the resulting regularity and singular-set bounds are outside this selected statement.

Comparator links

ResultComparator statement
A nonflat one-homogeneous Bernoulli minimizer in dimension sevenBernoulliNonflatInSeven.lean

Scope note on GitHub →