Amenability and paradoxicality in semigroups and C*-algebras Articles uri icon

publication date

  • August 2020

start page

  • 1

end page

  • 43


  • 2(108530)


  • 279

International Standard Serial Number (ISSN)

  • 0022-1236

Electronic International Standard Serial Number (EISSN)

  • 1096-0783


  • We analyze the dichotomy amenable/paradoxical in the context of (discrete, countable, unital) semigroups and corresponding semigroup rings. We consider also Følner type characterizations of amenability and give an example of a semigroup whose semigroup ring is algebraically amenable but has no Følner sequence. In the context of inverse semigroups S we give a characterization of invariant measures on S (in the sense of Day) in terms of two notions: domain measurability and localization.....


  • Mathematics


  • amenability; paradoxical decompositions; semigroups; amenable traces