题目：Fixed Point Indices and Fixed Words at Infinity of Selfmaps of Graphs

报告人：张强 副教授（西安交通大学）

地点：致远楼101室

时间：2021年04月14日 15：30-16:30

摘要：The index $\ind(\F)$ of a fixed point class $\F$ is a classical invariant in Nielsen fixed point theory. In this talk, for graph selfmaps, we introduce a new invariant $\ichr(\F)$ called the improved characteristic, and show that the two homotopy invariants mentioned above are exactly the same. Since the improved characteristic is totally determined by the endomorphism of the fundamental group, we give a group-theoretical approach to compute indices of fixed point classes of graph selfmaps. As consequences, we give some applicaitons on fixed words of endomorphisms of free groups. This is joint work with Zhao Xuezhi.

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