3 papers
math.GR2025
Non vanishing of the fourth bounded cohomology of free groups and codimension 2 subspaces
Thorben Kastenholz
In this note we prove that the fouth bounded cohomology of non-abelian free groups with trivial real coefficients is non-zero. In order to prove this, we establish a splitting argu…
math.GT2025
Simplicial volume of open books in dimension 4
Thorben Kastenholz
In this short note we adapt a proof by Bucher and Neofytidis to prove that the simplicial volume of 4-manifolds admitting an open book decomposition vanishes. In particular this sh…
math.AT2024
Simplicial volume of manifolds fibering with connected structure group
Thorben Kastenholz
In this note we investigate the simplicial volume of fiber bundles with connected structure group. We are able to show that if the structure group is either compact or a Lie group,…