时间 Time： 周五16:30-17:30，2019-5-31
A fundamental problem in 4-dimensional topology is the following geography question: "which simply connected topological 4-manifolds admit a smooth structure?" After the celebrated work of Kirby-Siebenmann, Freedman, and Donaldson, the last uncharted territory of this geography question is the "11/8-Conjecture''. This conjecture, proposed by Matsumoto, states that for any smooth spin 4-manifold, the ratio of its second-Betti number and signature is least 11/8.
Furuta proved the ''10/8+2''-Theorem by studying the existence of certain Pin(2)-equivariant stable maps between representation spheres. In this talk, we will present a complete solution to this problem by analyzing the Pin(2)-equivariant Mahowald invariants of powers of certain Euler classes in the RO(Pin(2))-graded equivariant stable homotopy groups of spheres. In particular, we improve Furuta's result into a ''10/8+4''-Theorem. Furthermore, we show that within the current existing framework, this is the limit. For the proof, we use the technique of cell-diagrams, known results on the stable homotopy groups of spheres, and the j-based Atiyah-Hirzebruch spectral sequence.
This is joint work with Michael Hopkins, Jianfeng Lin and XiaoLin Danny Shi.
徐宙利博士在北京大学获学士、硕士学位，博士就读于美国芝加哥大学，目前在美国麻省理工学院担任Moore Instructor（摩尔导师）职位。他与合作者于2017年在顶尖数学期刊Annals of Mathematics上发表论文，解决了球面61维稳定同伦群计算以及奇数维球面的光滑结构问题。球面同伦群与光滑结构是代数拓扑领域历史非常悠久的问题。