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Two-Generator Discrete Subgroups of Tree Automorphism Groups

Geometry/Topology

Speaker: Yukun Du, University of Georgia
Related Webpage: https://benniedu.github.io/
Location: 2112 MSB
Start time: Tue, Sep 29 2026, 2:10PM

Description

I will discuss the classification of discrete two-generator groups acting on locally finite trees. Under a small-geometry condition, the possible groups and quotient graphs are strongly constrained and can be classified explicitly. I will then explain how the picture becomes much richer beyond this regime, including higher-index amalgams and families with arbitrarily complicated quotient geometry.