Groups, Geometry, and Dynamics

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Volume 4, Issue 2, 2010, pp. 251–261
DOI: 10.4171/GGD/82

Published online: 2010-02-21

Sigma invariants of direct products of groups

Robert Bieri[1] and Ross Geoghegan[2]

(1) Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany
(2) Binghamton University, USA

The Product Conjecture for the homological Bieri–Neumann–Strebel–Renz invariants is proved over a field. Under certain hypotheses the Product Conjecture is shown to also hold over ℤ, even though D. Schütz has recently shown that the Conjecture is false in general over ℤ. Our version over ℤ is applied in a joint paper with D. Kochloukova [5] to show that for all n Thompson’s group F contains subgroups of type Fn which are not of type FPn + 1.

Keywords: Bieri–Neumann–Strebel invariants, product conjecture, products of groups

Bieri Robert, Geoghegan Ross: Sigma invariants of direct products of groups. Groups Geom. Dyn. 4 (2010), 251-261. doi: 10.4171/GGD/82