OpenAI reports a nearby Lagrangian counterexample

For some sufficiently large even N, the cotangent bundle of S⁹×Sᴺ⁻¹ contains a closed exact smoothly embedded Lagrangian diffeomorphic to the base that is not Hamiltonian isotopic to the zero section.

Sources for this record

What was already known

Nearby Lagrangian rigidity was established in selected low-dimensional and special cotangent-bundle cases, while the unrestricted conjecture predicted Hamiltonian isotopy for every closed exact Lagrangian.

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

Disproves the unrestricted nearby Lagrangian conjecture even when the Lagrangian is diffeomorphic to the base.

Limitations

The obstruction concerns embedding in the cotangent bundle, not a different abstract smooth type. Hamiltonian isotopies are compactly supported.

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, and prior-work review for non-notifying local inclusion; technical verification remains Reported.

Read this published revision