You can find my papers on Researchgate, or on arXiv.



  • Local Hilbert--Schmidt stability, joint with Maria Gerasimova and Pieter Spaas, 29 pages. Following the recent introduction of local permutation stability, we set up a general framework for local stability, and initiate the study of local Hilbert--Schmidt (HS) stability. We prove a version of the Hadwin--Shulman character criterion for amenable groups, provide several examples, and prove that property (T) is an obstruction to local stability.

  • Hopfian wreath products and the stable finiteness conjecture, joint with Henry Bradford, 28 pages. We study the problem of when a wreath product $\Delta \wr \Gamma$ is Hopfian, for finitely generated Hopfian groups $\Delta$ and $\Gamma$. Our main result establishes a strong connection between the case in which $\Delta$ is abelian, and the direct and stable finiteness conjectures of Kaplansky in group rings. Namely the latter hold true if and only if $\Delta \wr \Gamma$ is Hopfian whenever $\Delta$ is finitely generated and abelian and $\Gamma$ is finitely generated and Hopfian.

  • Median quasimorphisms on CAT(0) cube complexes and their cup products, joint with Benjamin Brück and Clara Löh, 34 pages. We extended vanishing results on cup products of Brooks quasimorphisms of free groups to cup products of median quasimorphisms, i.e., Brooks-type quasimorphisms of group actions on CAT(0) cube complexes. Special attention is paid to groups acting on trees and right-angled Artin groups.

  • Ultrametric analogues of Ulam stability of groups, 87 pages. I studied stability of metric approximations of groups, when the approximating groups are endowed with bi-invariant ultrametrics. The main case study is a $p$-adic analogue of Ulam stability, where unitary matrices are replaced by integral $p$-adic ones.

Chapter in book

  • In: Bounded Cohomology and Simplicial Volume - see "Editorial work" below. I wrote Chapter 9: "Extension of quasicocycles from hyperbolically embedded subgroups", 15 pages. The text is an exposition of this paper, thought for people who are interested in bounded cohomology but are not necessarily familiar with the notions from geometric group theory that are involved. It is a more detailed version of a "What is?" talk that I gave (see below).


Editorial work