Comparison property for amenable group actions

：张国华（复旦大学）
：2022-03-28 15:00
：腾讯会议ID：804 753 961（无密码）

报告人：张国华（复旦大学）

时  间：3月28日下午15:00

地  点：腾讯会议ID：804 753 961（无密码）

内容摘要:

Let a countable discrete group G act on a zero-dimensional compact metric space X. We say that the action admits comparison if for any clopen sets A and B, the condition, that for every G-invariant measure m on X we have the sharp inequality m(A)<m(B), implies that A is subequivalent to B, that is, there exists a finite clopen partition {A₁, ..., A_k} for A, and elements g₁, ..., g_k in G such that g₁(A₁), ..., g_k(A_k) are disjoint clopen subsets of B. We prove this property for actions of groups whose every finitely generated subgroup has subexponential growth. This is a joint work with Professor Tomasz Downarowicz.

个人简介：

张国华，复旦大学数学科学学院教授，博士生导师。主要研究领域为拓扑动力系统与遍历理论，先后在包括Mem. Amer. Math. Soc.，J. Reine Angew. Math.，Adv. Math.，Trans. Amer. Math. Soc.，J. Funct. Anal.等国际期刊发表学术论文三十余篇。主持多个国家自然科学基金项目，2017年获基金委国家优秀青年科学基金资助。

 

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