科学研究
报告题目:

Comparison property for amenable group actions

报告人:

张国华 教授(复旦大学)

报告时间:

报告地点:

理学院东北楼四楼报告厅(404)

报告摘要:

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, ..., Ak for A, and elements g1, ..., gk in G such that g1(A1), ..., gk(Ak) 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.

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