Descriptive complexity of subsets of the space of finitely generated groups

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BENLİ M. G., KAYA B.

Expositiones Mathematicae, vol.40, no.4, pp.1116-1134, 2022 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 40 Issue: 4
  • Publication Date: 2022
  • Doi Number: 10.1016/j.exmath.2022.08.001
  • Journal Name: Expositiones Mathematicae
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, MathSciNet, zbMATH
  • Page Numbers: pp.1116-1134
  • Keywords: Finitely generated groups, Marked groups, Descriptive complexity, Borel hierarchy, AMENABLE-GROUPS
  • Middle East Technical University Affiliated: Yes

Abstract

© 2022 Elsevier GmbHIn this paper, we determine the descriptive complexity of subsets of the Polish space of marked groups defined by various group theoretic properties. In particular, using Grigorchuk groups, we establish that the sets of solvable groups, groups of exponential growth and groups with decidable word problem are Σ20-complete and that the sets of periodic groups and groups of intermediate growth are Π20-complete. We also provide bounds for the descriptive complexity of simplicity, amenability, residually finiteness, Hopficity and co-Hopficity. This paper is intended to serve as a compilation of results on this theme.