HigherHyper · Higher Hyperbolicity

Hyperbolicity pervades modern mathematics. It is the dominant type of geometry both in low-dimensional topology and group theory, and in such regimes it is a well-understood concept. Such a comprehensive understanding, however, does not extend to higher dimensions and other higher manifestations of hyperbolicity, and this proposal will attempt to change that by focusing on fibring, volume, isoperimetric inequalities, and the Atiyah conjecture.One of the most pressing problems that geometric topology faces today is to devise a way of adapting Thurston's philosophy to high dimensions. In particular, it is paramount that we answer the question of whether all hyperbolic manifolds in odd dimensions virtually fibre over the circle. One of the main goals of this proposal is to prove this conjecture for manifolds with cubical fundamental groups, a crucial and rich class, and to introduce an original, robust, and flexible method of producing positive examples.Much of the study of hyperbolic three-dimensional manifolds revolves around the concept of their volume. I will advance a natural notion of volume that covers all hyperbolic groups, whether of geometric provenance or not. This will consolidate the field, and will vastly extend the range of currently existing tools.Homologically, hyperbolicity manifests itself as a linear isoperimetric inequality in dimension one. I plan to shed light on the deeply mysterious meaning of such an inequality in higher dimensions, weaving together multiple recent advances like theorems of Kleiner--Lang and my work with Kropholler and Nowak into a single fruitful thread.The three most important classical open questions about hyperbolic groups are residual finiteness, soficity, and the Atiyah conjecture. I intend to prove the last one using a fundamentally new approach. In the process, fresh insights into the structure of approximate subgroups will be gained that will open new avenues of inquiry into the problem of soficity.