Big mapping class groups are not extremely amenable

Yusen Long

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arXiv · 2307.12408

Big mapping class groups are not extremely amenable

Yusen Long

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Abstract

This paper uses the renowned Kechris-Pestov-Todor\v{c}evi\'{c} machinery to show that (big) mapping class groups are not extremely amenable unless the underlying surface is a sphere or a once-punctured sphere, or equivalently when the mapping class group is trivial. The same techniques also show that the pure mapping class groups, as well as compactly supported mapping class groups, of a surface with genus at least one can never be extremely amenable.

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Yusen Long. 2023-07-23. Big mapping class groups are not extremely amenable. https://arxiv.org/abs/2307.12408

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