Hyperbolic isometries of systolic complexes

Tomasz Pawel Prytula

Abstract

The main topics of this thesis are the geometric features of systolic complexesarising from the actions of hyperbolic isometries. The thesis consists ofan introduction followed by two articles.Given a hyperbolic isometry h of a systolic complex X, our central theme isto study the minimal displacement set of h and its relation to the actions of h onX and on the systolic boundary ∂X. We describe the coarse-geometric structureof the minimal displacement set and establish some of its properties that can beseen as a form of quasi-convexity. We apply our results to the study of geometricand algebraic-topological features of systolic groups. In addition, we provide newexamples of systolic groups.In the first article we show that the minimal displacement set of a hyperbolicisometry of a systolic complex is quasi-isometric to the product of a tree andthe real line. We use this theorem to construct a low-dimensional model for theclassifying space EG for a group G acting properly on a systolic complex, andto describe centralisers of hyperbolic isometries in systolic groups.In the second article we are interested in the induced action of h on thesystolic boundary, and particularly in the fixed points of this action. The maintheorem gives a characterisation of the isometries acting trivially on the boundaryin terms of their centralisers in systolic groups.
Original languageEnglish
PublisherDepartment of Mathematical Sciences, Faculty of Science, University of Copenhagen
Publication statusPublished - 2017

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