March 20 (Fri) 2026, 10:30 ~ 11:30 (Asan science building 525)
Title: Markoff and Lagrange spectra for Hecke groups
Speaker: Byungchul Cha (Hongik University)
Abstract:
For an integer $q\ge 3$, \emph{the Hecke group $G_q$ of index $q$} is the subgroup generated by $z\mapsto -1/z$ and $z\mapsto z + 2\cos(\pi/q)$ of the orientation-preserving isometry group of the upper half plane. We study the structure of Markoff and Lagrange spectra of $G_q$. In particular, we characterize the initial discrete parts of these spectra. This mirrors classical results on the Markoff and Lagrange spectra of the real line. This is joint work with Dong Han Kim.
April 10 (Fri) 2026, 11:00 ~ 12:00 (Asan science building 525)
Title: Goldfeld conjecture for genus 2 curves
Speaker: Keunyoung Jeong (Chonnam National University)
Abstract:
TBA
May 1 (Fri) 2026, 11:30 ~ 12:30 (Asan science building 525)
Title: On the Non-tempered Gan-Gross-Prasad Conjecture
Speaker: Jaeho Haan (KAIST)
Abstract:
In this talk, I will provide an in-depth explanation of the Gan-Gross-Prasad conjecture. First, I will discuss Arthur's endoscopic classification of classical groups, which can be considered a monumental achievement in the theory of automorphic representations. Within this framework, I will introduce the tempered GGP conjecture and explain how it has been extended to the generalized GGP conjecture, which includes the non-tempered case. Finally, I will present results related to the non-tempered GGP conjecture.
May 29 (Fri) 2026, 10:30 ~ 11:30 (Asan science building 525)
Title: Serre weight conjectures and modularity lifting for GSp4
Speaker: Heejong Lee (KIAS)
Abstract:
TBA