Geometry & Topology

Geometry of pseudocharacters

Jason Fox Manning

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If G is a group, a pseudocharacter f:G is a function which is “almost” a homomorphism. If G admits a nontrivial pseudocharacter f, we define the space of ends of G relative to f and show that if the space of ends is complicated enough, then G contains a nonabelian free group. We also construct a quasi-action by G on a tree whose space of ends contains the space of ends of G relative to f. This construction gives rise to examples of “exotic” quasi-actions on trees.

Article information

Geom. Topol., Volume 9, Number 2 (2005), 1147-1185.

Received: 22 August 2003
Revised: 9 March 2005
Accepted: 8 June 2005
First available in Project Euclid: 20 December 2017

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Digital Object Identifier

Mathematical Reviews number (MathSciNet)

Zentralblatt MATH identifier

Primary: 57M07: Topological methods in group theory
Secondary: 05C05: Trees 20J06: Cohomology of groups

pseudocharacter quasi-action tree bounded cohomology


Manning, Jason Fox. Geometry of pseudocharacters. Geom. Topol. 9 (2005), no. 2, 1147--1185. doi:10.2140/gt.2005.9.1147.

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