报告人: 张毅超教授，哈尔滨工业大学 题目: Weakly holomorphic modular forms with sign vectors: Part I and Part II 地点:   知新楼B1044 时间:   2015年10月13日　9:30-10:20, 10:30-11:30 Abstract:   In the first part, we introduce weakly holomorphic modular forms with sign vectors and show an isomorphism between scalar-valued and vector-valued modular forms. This can be applied to simplify Borcherds lift (also known as Borcherds automorphic product).   In the end, we explain some of the full-level properties of such modular forms, including the Zagier duality.     In the second part, we generalize a result of Siegel on some divisibility of Fourier coefficient,   as another full-level property. We then move on to a joint work with H.H. Kim and K.-H. Lee on automorphic corrections.In order to avoid some serious technicalities, this last part on automorphic correction will be a little sloppy.