Hyperbolic 4-manifolds with perfect circle-valued Morse functions
Geometric Topology
2025-09-16 v3 Differential Geometry
Abstract
We exhibit some (compact and cusped) finite-volume hyperbolic four-manifolds M with perfect circle-valued Morse functions, that is circle-valued Morse functions with only index 2 critical points. We construct in particular one example where every generic circle-valued function is homotopic to a perfect one. An immediate consequence is the existence of infinitely many finite-volume (compact and cusped) hyperbolic 4-manifolds having a handle decomposition with bounded numbers of 1- and 3-handles, so with bounded Betti numbers , and rank of .
Cite
@article{arxiv.2009.04997,
title = {Hyperbolic 4-manifolds with perfect circle-valued Morse functions},
author = {Ludovico Battista and Bruno Martelli},
journal= {arXiv preprint arXiv:2009.04997},
year = {2025}
}
Comments
33 pages, 14 figures. The third version contains more examples and some proofs are expanded