Rational group ring elements with kernels having irrational dimension

Abstract

We prove that there are examples of finitely generated groups G together with group ring elements Q \in \bbQ G for which the von Neumann dimension \dim_{LG}\ker Q is irrational, so (in conjunction with other known results) answering a question of Atiyah.

35 pages, 1 figure; [TDA 3/12/13:] Updated version incorporating referee's suggestions

References in corpus (1)

• Free Lamplighter Groups and a Question of Atiyah

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