Patterns in Kazhdan-Lusztig polynomials

Jon Brundan

There are not too many symmetries in two dimensions, or put more mathematically, there are only three crystallographic groups of rank 2: the finite groups A_2, B_2 and G_2. But they have a remarkable amount of structure associated to them. I will talk about some polynomials -- the Kazhdan-Lusztig polynomials discovered (by guess who) in 1979 -- which arise in the study of reflection groups like these. Some beautiful geometric patterns emerge quite unexpectedly even in just two dimensions. If only I could draw the three dimensional case too...