A weakly continuous near-action of a Polish group on a standard Lebesgue measure space is whirly if for every of strictly positive measure and every neighbourhood of identity in the set has full measure. This is a strong version of ergodicity, and locally compact groups never admit whirly actions. On the contrary, every ergodic near-action by a Polish L'evy group in the sense of Gromov and Milman, such as , is whirly (Glasner–Tsirelson–Weiss). We give examples of closed subgroups of the group of measure preserving automorphisms of a standard Lebesgue measure space (with the weak topology) whose tautological action on is whirly, and which are not L'evy groups, thus answering a question of Glasner and Weiss.

生成讲解博客的中文版本

生成AI智能校验的中文版本