OpenAI reports a nonresidually finite hyperbolic group

There exists a torsion-free word-hyperbolic group that is not residually finite.

Sources for this record

What was already known

Residual finiteness held for several established classes of hyperbolic groups, while the general question for word-hyperbolic groups remained open.

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

Gives a negative answer to the long-standing residual-finiteness question for hyperbolic groups.

Limitations

The selected formalized statement is the group construction; nonlinearity over every field is not part of it.

Technical verification Formal (Lean 4)

OpenAI reports a Lean proof matching the selected claim.

Formal checking

The pinned Lean note constructs a torsion-free word-hyperbolic group that is not residually finite.

Checker
OpenAI-reported Lean 4 / Comparator
Scope
There exists a torsion-free word-hyperbolic group that is not residually finite.
Basis
Reported by the linked checker
Evidence source

Checking a formal statement does not establish that it matches the original problem.

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 scoped checking review for non-notifying local inclusion.

Read this published revision