学 术 报 告
报告题目：Virtual Betti numbers and virtual symplecticity of 4-dimensional mapping tori
报告时间：2018年7月30日15:30-16:30
报告地点：创新园大厦A1101报告厅
报告人：Professor Tian-Jun Li（University of Minnesota）
报告摘要: We compute the virtual first Betti numbers of 4-manifolds fibering over S^1 with prime 3-manifold fiber. As an application, we show that if such a manifold is symplectic with nonpositive Kodaira dimension, then the fiber itself is a sphere or torus bundle over S^1. In a different direction, we prove that if the 3-dimensional fiber of such a 4-manifold is virtually fibered then the 4-manifold is virtually symplectic unless its virtual first Betti number is 1. This is a joint work with Yi Ni.
报告人简介：Tian-Jun Li, Professor, Associate Head at School of Mathematics, University of Minnesota.
BS, Beijing University; PhD, Brandeis University; Postdoc, Yale University, Institute for Advanced Study; Assistant Professor, Princeton University.
Research interests: four manifold theory and symplectic geometry.
Main contributions: Seiberg-Witten theory of smooth 4-manifolds with b+=1, Classifications of symplectic rational and ruled 4-manifolds and symplectic and Lagrangian surfaces, topology of symplectic Calabi-Yau surfaces, minimal genus problem, symplectic birational geometry in higher dimension.
报告校内联系人：雷逢春 教授 联系电话：84706472
