세미나 및 콜로퀴엄

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구글 Calendar나 iPhone 등에서 구독하면 세미나 시작 전에 알림을 받을 수 있습니다.

Let $E$ be an elliptic curve over the rational number field $\mathbb{Q}$. Selmer Groups and Ideal Class Groups are important and widely-studied objects in number theory. Brumer and Kramer studied relations between these two objects in their paper in 1977. They actually found an upper bound for the $2$-Selmer rank of $E$ in terms of the ideal class group of a certain cubic field extension of $\mathbb{Q}$. As an application, they determined the Mordell-Weil ranks of (most) elliptic curves of prime conductor assuming the BSD conjecture. In this talk, we will talk about a generalization of Brumer-Kramer's work to the case of elliptic curves over an arbitary number field. We will give both upper and lower bounds for the $2$-Selmer rank in terms of a (modified) ideal class group, and the bounds turn out to be sharp in many cases. This is joint work with Hwajong Yoo. (If you would like to join the seminar, please let me(Bo-Hae Im) know so that I can send you the Zoom link.)
Host: Bo-Hae Im     미정     2020-10-12 11:40:30
In this talk, I will present a recent work in collaboration with physicists on the analysis of real time Transmission Electron Microscopy (TEM) images to understand molecular transition from crystal solid state to liquid state. Molecules are deposited on graphene with multilayer structures, which are projected and overlaid in noisy 2d TEM images. The problem is to find all the molecular centers in the extremely noisy 2d images where projected molecules are overlaid and to track the centers across the image frames. Before discussing the method that we considered, I will give a brief history in the development of image segmentation techniques with some theoretical and numerical details of old fashioned methods. Then, our method of image segmentation for molecular center identification follows.
영어     2020-09-09 11:04:33
The Lamb dipole is a traveling wave solution to the two-dimensional Euler equations introduced by S. A. Chaplygin (1903) and H. Lamb (1906) at the early 20th century. We prove orbital stability of this solution based on a vorticity method initiated by V. I. Arnold. Our method is a minimization of a penalized energy with multiple constraints that deduces existence and orbital stability for a family of traveling waves. As a typical case, orbital stability of the Lamb dipole is deduced by characterizing a set of minimizers as an orbit of the dipole by a uniqueness theorem in the variational setting. This is a joint work with K. Abe (Osaka City Univ).
Host: 강문진     미정     2020-10-25 19:54:07