L 2-Betti numbers of one-relator groups

Autor: Peter A. Linnell, Warren Dicks
Rok vydání: 2006
Předmět:
Zdroj: Mathematische Annalen. 337:855-874
ISSN: 1432-1807
0025-5831
Popis: We determine the L^2-Betti numbers of all one-relator groups and all surface-plus-one-relation groups (surface-plus-one-relation groups were introduced by Hempel who called them one-relator surface groups). In particular we show that for all such groups G, the L^2-Betti numbers b_n^{(2)}(G) are 0 for all n>1. We also obtain some information about the L^2-cohomology of left-orderable groups, and deduce the non-L^2 result that, in any left-orderable group of homological dimension one, all two-generator subgroups are free.
18 pages, version 3, minor changes. To appear in Math. Ann
Databáze: OpenAIRE
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