OpenAI claim summary for Math-1987
mathematicsTop Open Problemscontributionliterature_reportClaim: literature report
Summary of a claim published in openai/math; not a claim by this platform.
For the main hyperbolic example any such Rips metric would give a geometric CAT(0) action: the finite generating set makes the Rips complex locally finite with finite quotient, and a compatible complete locally compact geodesic metric is proper. This contradicts the core no-geometric-CAT(0) conclusion. Within these assumptions, this is a claimed negative answer to the stated question.
Limitations: The linked openai/math material has not been examined or verified by the platform.
Manuscript
Contents
Questions in Geometric Group Theory — Q 1.5
OpenAI's claim
OpenAI presents a counterexample in the selected manuscript. A hyperbolic group with a finite classifying complex is claimed to admit no proper and cocompact isometric action with proper complete CAT$0$ target.Mathematical statement of the claimed result
Result 1.
The source constructs a finite, connected, aspherical simplicial complex $K$ of dimension two. In its universal cover, a length-$\ell$ combinatorial loop admits a triangular disk diagram with at most $C\ell$ faces, for one finite constant $C$. Nevertheless, \[ \pi_1K\text{ has no proper cocompact isometric action on a proper complete CAT}(0)\text{ space}. \] The linear filling estimate makes $\pi_1K$ word-hyperbolic. Within the homotopy class of $K$, no simplicial complex with finitely many simplices admits a geodesic length metric compatible with its topology and locally CAT$0$; the claim also excludes such a locally CAT$-1$ metric.Outline of the argument
Nested incidence tables produce finite relations with a linear disk-filling bound. Conditional sampling creates a limiting configuration of controlled energy, and its geometric obstruction contradicts any proposed CAT$0$ action; the finite aspherical model preserves the topological finiteness claim.Formal verification
For family 257, the documented construction gives a finite aspherical hyperbolic group model without a geometric proper-complete CAT$0$ action. The stronger dimension-two and all locally CAT$0$ model claims are excluded. The listed Comparator files areHyperbolicObstruction.lean. Named declarations include OAI.HyperbolicObstruction.main. This site has not executed the Lean code. The scope descriptions do not certify the remaining manuscript arguments.Status caveat
OpenAI attributes these manuscripts to work by an internal model. Its release cautions that arguments without formalization can contain mistakes. This catalogue has not independently checked the proofs; the labels report the mathematical claims attributed to OpenAI.Sources
- OpenAI, A hyperbolic group with no geometric CAT$0$ action, 2026-09-25; citation key
OAI:A-hyperbolic-group-with-no-geometric-CAT0-action-September-25-2026. PDF (GitHub); PDF (direct); Manuscript page and citation; Latest version; Statement source: thm:main. - Family 257: Lean scope.
- Comparator HyperbolicObstruction.json.
- Comparator HyperbolicObstruction.lean.
- OpenAI catalogue entry.