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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