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Spectral scalar curvature and Urysohn width in dimension three

OpenAI · October 5, 2026

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Abstract

Every connected complete smooth Riemannian three-manifold without boundary satisfying $-4\Delta+\mathop{\mathrm{Scal}}\nolimits \ge\lambda\gt 0$ as a quadratic-form inequality admits a continuous map to a graph whose entire fibers have diameter at most $500/\sqrt\lambda$ in the original metric. No orientability, spin, compactness, or bounded-geometry assumption is required.

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Collected automatically by AI tools (Claude Opus 5.5 and GPT-6 Astra, 2026-10-21) and not checked by a person. May be wrong or incomplete. Report an error.

Follow-up works

  • Yuchen Bi, A note on the cube inequality (arXiv:2610.28390, v1 20 Oct 2026). Its abstract says it adapts ideas from "No. 336" of the OpenAI release, but the only manuscript it cites is the companion paper Positive scalar curvature and uniform codimension-two width, not this one. [family-level]

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Cite

@misc{OAI:Spectral-scalar-curvature-and-Urysohn-width-in-dimension-three-October-5-2026,
  author = {{OpenAI}},
  title = {{Spectral scalar curvature and Urysohn width in dimension three}},
  howpublished = {OpenAI Math Release preprint
                  \href{https://github.com/openai/math/blob/main/preprints/Spectral-scalar-curvature-and-Urysohn-width-in-dimension-three-October-5-2026/spectral-urysohn-three-manifolds.pdf}{OAI:Spectral-scalar-curvature-and-Urysohn-width-in-dimension-three-October-5-2026}},
  year = {2026}
}

Family 336: Spectral scalar curvature, Urysohn width, and macroscopic dimension

Every complete connected smooth boundaryless n-manifold, n ≥ 3, satisfying $-4\Delta+\mathrm{Scal}\ge1$ as a quadratic-form inequality admits a continuous map to a simplicial complex of dimension at most $n-2$ whose entire fibers have diameter bounded only by n in the original metric. This strengthens Gromov's width conclusion to spectral scalar curvature. Universal covers of closed positive-scalar-curvature manifolds also have continuous macroscopic dimension at most $n-2$ for every n ≥ 2.

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