报告题目：Intermediate algebras associated with a compact topological dynamical system (X, G)

报告人： Tattwamasi Amrutam（以色列本·古里安大学数学系）

报告时间：2023年5月26日13:00-14:00

报告地点：腾讯视频会议（线上）会议ID：169 563 932

校内联系人：江永乐 副教授  联系电话：84708351-8033

报告摘要：Let G be a countable group and (X, G) a compact topological dynamical system. We study the question of the existence of an intermediate C*-subalgebra A of the form C^*_r(G)<A<C(X)\rtimes_rG, which is not of the form A=C(Y)\rtimes_rG, corresponding to a factor map (X, G)->(Y,G). Here C^*_r(G) and C(X)\rtimes_rG are the reduced C*-algebras of G and (X, G) respectively. Our main results are the following:

(1) For G which is not C*-simple, if (X, G) admits a G-invariant probability measure then such a sub-algebra always exists.

(2) For G=Z and (X, G) an irrational rotation of the circle X=S^1, we give a full description of all these non-crossed-product subalgebras in terms of ideals of C^*_r(Z).

报告人简介：Tattwamasi Amrutam，2021年获得美国休斯顿大学博士学位（导师：Mehrdad Kalantar教授），现为以色列本·古里安大学博士后(合作导师: Yair Hartman)。主要研究方向包括一般群作用的动力系统和算子代数。已在TAMS，IMRN, JFA，ETDS等主流期刊发表多篇论文。