<BK21-QSMS Toric Geometry Seminar>

This talk is based on the paper - Lagrangian fibers of Gelfand-Cetlin systems – by Cho, Kim and Oh. I will explain two topics to understand the one of the main theorems in this paper. Before going into the story, I will briefly outline the main theorem. The first topic is the co-adjoint orbit which is a domain of the Gelfand-Cetlin system, and symplectic structure on this orbit. The second topic is the Gelfand-Cetlin system, and then I will introduce a polytope which can be obtained from the system.