Abstract harmonic analysis Amenability and invariant means Concept
Amenable semigroup
Summary
A semigroup is left amenable if there is a mean on its bounded functions that is invariant under left translations. This extends the notion of amenable group to semigroups, where left and right versions can differ. Every commutative semigroup is amenable, and the free semigroup on two generators is not left amenable. Day developed much of the theory of amenable semigroups, including fixed point characterizations.
Further reading
About this page
| Tag | GA3TVJ9A0G |
|---|---|
| URI | m2://GA3TVJ9A0G |
| Kind | concept |
| Writing | W0 stub |
| MSC | 43A07, 20M30 |
| Changed | 3 November 2026 |
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