Embeddings into the ultrapower of the Jiang-Su algebra
Pi, J Bouwen, B (13 Jun 2025)

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Frequency synchronization induced by frequency detuning.
Ocampo-Espindola, J Bick, C Motter, A Kiss, I Science advances volume 11 issue 24 eadu4114 (11 Jun 2025)
Community detection on directed networks with missing edges
Pedreschi, N Lambiotte, R Bovet, A Journal of Physics: Complexity (18 Jun 2025)
Lifting couplings in Wasserstein spaces
Perrone, P Compositionality volume Volume 7 (2025) (07 May 2025)
Wed, 25 Jun 2025
15:00

Boundary cubulation is a pathway to residual finiteness

Thomas Ng
(Brandeis University)
Abstract

Actions on CAT(0) cube complexes are powerful geometric tool for both algebraically decomposing groups and establishing subgroup separability results.  I will describe boundaries associated to hyperbolic and relatively hyperbolic groups. With a focus on (quotients of) free products, I will discuss variations on a boundary criteria of Bergeron—Wise for exhibiting cocompact actions on CAT(0) cube complexes.  I will explain some ideas on how to use these tools to show that most (small-cancellation or random density) quotients of free products preserve residual finiteness. This is based on multiple joint works with subsets of Einstein, Krishna MS, Montee, and Steenbock.

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