English

On the classifying space of a Morse flow category

Algebraic Topology 2026-03-26 v1

Abstract

We show that the classifying space of the flow category of a \emph{tame} Morse function on a smooth, closed manifold MM recovers the homotopy type of MM, thereby addressing a claim in a preprint of Cohen--Jones--Segal. The tameness assumption is that the compactified moduli spaces of broken gradient trajectories are locally contractible, ensuring the flow category is topologically well-behaved. We construct a Morse function and Riemannian metric on S2×S1S^2\times S^1 for which the associated flow category fails to recover the correct homotopy type, showing that the tameness hypothesis is crucial. Together, these results clarify the extent to which transversality assumptions can be relaxed so that the flow category models the homotopy type of the underlying manifold.

Keywords

Cite

@article{arxiv.2603.23695,
  title  = {On the classifying space of a Morse flow category},
  author = {Maxine E. Calle and Fangji Liu},
  journal= {arXiv preprint arXiv:2603.23695},
  year   = {2026}
}

Comments

33 pages, 13 figures, comments welcome!