Jingyan Li , Pravin Kumar , Jie Wu

Xiaolei Wu

Thursday, October 8, 2026 3:00 PM - 4:00 PM

A3-4-301

Zoom 242 742 6089 (BIMSA)

The class of residually finite rationally solvable (RFRS) groups, introduced by Ian Agol , played a key role in his solution to the virtual Haken conjecture. Besides subgroups of right angled Artin groups, there are not many examples of groups that are RFRS. Agol asked in his 2014 ICM address whether braid groups are (virtually) RFRS. We show discuss basic properties of RFRS groups then indicate that braid groups are not RFRS in general. We further explain ideas to show that pure braid groups are always RFRS. This is a joint work with Shengkui Ye.

Xiaolei Wu is a young investigator at the Shanghai Center for Mathematical Sciences, Fudan University. He received his Ph.D. in Mathematics from SUNY Binghamton in 2014. His research interests include geometric group theory, manifold topology, and algebraic K-theory, with particular focus on finiteness properties of groups, Artin and Thompson groups, big mapping class groups, and the Farrell–Jones Conjecture.