OpenAI reports arbitrary-constant NP-hardness for Uniform Sparsest Cut

For every fixed C>1, approximating Uniform Sparsest Cut within factor C is NP-hard on graphs with nonnegative rational capacities and unit demand between every pair of distinct vertices.

Sources for this record

What was already known

The manuscript distinguishes earlier hardness for nonuniform demands and conditional connections through Unique Games from unconditional hardness for the uniform-demand problem.

AI involvement AI-led

OpenAI credits itself as manuscript author and states that its internal frontier model produced the results in this release. Individual human input is not detailed enough to establish task-only autonomy.

OpenAI is named as author on the manuscript, and its release attributes the results to an internal frontier model. The individual human input is not detailed enough to establish autonomy.

Importance Major

Rules out every fixed constant approximation ratio for Uniform Sparsest Cut unless P=NP.

Limitations

The demand is uniform and capacities are nonnegative rationals. The linked Lean scope checks a semidefinite integrality gap, not this NP-hardness reduction; a completed check of the reduction remains undocumented.

Technical verification Reported

Reported is the default when evidence for a higher level is insufficient. The OpenAI-authored manuscript reports and argues the result, but the reviewed sources do not document a completed check of the full assessed claim.

Human understanding Few

Few is the default when evidence for a higher level is insufficient. No named person is documented as explaining the central argument for this assessed contribution.

Correction and publication history

2026-10-18 · publication

Primary manuscript, attribution, prior-work, and Lean-scope mismatch review for non-notifying local inclusion.

Read this published revision