Abstract:Given a 4-manifold X bounded by a Seifert manifold, one can use the circle action on the boundary to define a diffeomorphism on X, called the boundary Dehn twist. Such boundary Dehn twist naturally arises from singularity theory. A recent result by Konno-Mallick-Taniguchi shows that when X is a certain Milnor fiber, this boundary Dehn twist is topologically isotopic to the identity bu...
AbstractThe goal of this talk is to explain joint work in progress with Jack Sempliner on the construction of "exotic" Hecke correspondences between the mod p fibers of different Shimura varieties of Hodge type. Our work generalizes forthcoming work of Xiao-Zhu; our results cover the new situation where the groups underlying the two different Shimura varieties are allowed to be to be non-isomor...