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تسجيل مستخدم جديدAmenability of semigroups and common multiples in $ell^1_+$
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تأليف
Tobias Fritz
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In this note, we prove that a semigroup $S$ is left amenable if and only if every two nonzero elements of $ell^1_+(S)$ have a common nonzero right multiple, where $ell^1_+(S)$ is the positive part of the Banach algebra $ell^1(S)$, or equivalently the semiring of finite measures on $S$. This characterization of amenability is new even for groups.
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