Group-graded rings satisfying the strong rank condition

Peter Kropholler, Karl Lorensen

Research output: Contribution to journalArticle

Abstract

A ring R satisfies the strong rank condition (SRC) if, for every natural number n, the free R-submodules of Rn all have rank ≤n. Let G be a group and R a ring strongly graded by G such that the base ring R1 is a domain. Using an argument originated by Laurent Bartholdi for studying cellular automata, we prove that R satisfies SRC if and only if R1 satisfies SRC and G is amenable. The special case of this result for group rings allows us to prove a characterization of amenability involving the group von Neumann algebra that was conjectured by Wolfgang Lück. In addition, we include two applications to the study of group rings and their modules.

Original languageEnglish (US)
Pages (from-to)326-338
Number of pages13
JournalJournal of Algebra
Volume539
DOIs
StatePublished - Dec 1 2019

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Graded Ring
Group Ring
Ring
Amenability
Von Neumann Algebra
Group Algebra
Natural number
Cellular Automata
If and only if
Module

All Science Journal Classification (ASJC) codes

  • Algebra and Number Theory

Cite this

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Group-graded rings satisfying the strong rank condition. / Kropholler, Peter; Lorensen, Karl.

In: Journal of Algebra, Vol. 539, 01.12.2019, p. 326-338.

Research output: Contribution to journalArticle

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