Johansson Anders , Manyao Deng , Ruize Gao , Liyan Han , Zhen Li , Jin Liu , Fei Long , Dongbo Shi , Ke Tang , Xing Yan , Qi Zhang

Shuo Qin

Friday, October 16, 2026 3:00 PM - 4:00 PM

A3-2-303

Zoom 242 742 6089 (BIMSA)

Why can two initially comparable alternatives end up with very different long-run shares? This talk introduces reinforced stochastic processes through Pólya urns, simple probabilistic models in which current popularity influences future choices. With linear reinforcement, early random fluctuations persist and the limiting proportion remains random. With nonlinear reinforcement, sublinear feedback restores balance, whereas superlinear feedback leads to eventual monopoly. I will then consider two interacting urns, representing partially connected populations whose choices depend on both local and aggregate proportions. In the superlinear regime, the interaction strength produces a phase transition between persistent local disagreement and a common monopoly. The talk is introductory and assumes only basic probability.

Shuo Qin has been the first Chern Instructor at BIMSA. He obtained a Ph.D. in mathematics in 2024 from New York University under the supervision of Prof. Pierre Tarrès. His work is in probability theory, especially in random processes with memory or reinforcement.