Speaker: Pro.Zhongtao Wu（The Chinese University of Hong Kong）

Title: Genus, norm and complexity

Time: Wed, May.15, 2019, AM:10:00-11:00

Location: Room 4131, Building No.4, Wushan Campus

Abstract:

        In low-dimensional topology, genus is the most basic invariant that enables to give a complete classification of closed oriented surfaces.  We discuss an analogous result for non-orientable surfaces.  Then, we introduce various norms of 3-manifolds, which roughly compute the minimal genus of surfaces that represent a given homology class.  In particular, we give a bound for one of the norms that involves non-orientable surfaces.  Finally, we use the bound to estimate the complexity of 3-manifolds, that is, the minimal number of tetrahedra needed in triangulation.