报告人：朱可佳（湖南大学）
时间：2026年6月23日14:00-15:00
地点：物质科研楼C1124
Motivated by the question of whether braid groups are CAT(0), we investigate the CAT(0) behavior of fundamental groups of plane curve complements and certain universal families. If C is the branch locus of a generic projection of a smooth, complete intersection surface to P^2 , we show that the fundamental group of P^2 ∖ C is CAT(0). In the other direction, we prove that the fundamental group of the universal family associated with the singularities of type E6, E7, and E8 is not CAT(0).
We also show that when the degree of C is at most 5, the fundamental group of P^2 ∖ C is linear and virtually polyfree, as a consequence, we answer positively the question of Zariski on the residually finiteness of the fundamental group of P^2 ∖ C for all plane curves of degree at most 5.
This is joint work with C. Bregman, A. Libgober, and Shengkui Ye.
