hsfzLZH1's Homepage
2026
- Does the unit sphere remember the whole Banach space?
- A sphere at infinity determines hyperbolic three-dimensional geometry
- Why Thompson’s group F cannot have almost invariant finite sets
- A group whose algebra needs two dimensions but whose space needs three
- An infinite group described by finitely many rules, with only finite-order elements
- When an algorithmic group fits inside a simple group with finite structure in every dimension
- Amenability decides when bounded actions can be made unitary and approximate actions repaired
- Negative curvature does not guarantee detection by finite groups
- An infinite simple amenable group with a finite presentation
- Artin groups: complete topological models, controlled subgroups, and a curvature obstruction