A Geometric Study of Commutator Subgroups

Citation

Zhuang, Dongping (2009) A Geometric Study of Commutator Subgroups. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/J566-2537. https://resolver.caltech.edu/CaltechETD:etd-05152009-115934

Abstract

Let G be a group and G' its commutator subgroup. Commutator length (cl) and stable commutator length (scl) are naturally defined concepts for elements of G'. We study cl and scl for two classes of groups. First, we compute scl in generalized Thompson's groups and their central extensions. As a consequence, we find examples of finitely presented groups in which scl takes irrational (in fact, transcendental) values. Second, we study large scale geometry of the Cayley graph of a commutator subgroup with respect to the canonical generating set of all commutators. When G is a non-elementary hyperbolic group, we prove that, for any n, there exists a quasi-isometrically embedded, dimension n integral lattice in this graph. Thus this graph is not hyperbolic, has infinite asymptotic dimension, and has only one end. For a general finitely presented group, we show that this graph is large scale simply connected.

Thesis Files