Thursday, September 26, 2024

2024-09-26 / 14:30 ~ 15:30

by 조재현()

Let J={a,b} be an unordered pair of F_q, and E_J the associated elliptic curve of the form y^3=(x-a)(x-b) over \F_q. We show that there are "only three possible values" for the trace of Frobenius of E_J. Furthermore, these three values can be computed via a certain Jacobi sum. As applications, we first compute the average analytic rank of a certain family of elliptic curves. Next, we generate elliptic curves with designated extremal primes. After computing a variant of the n-th moment of Traces of Frobenius, we give explicit values and average values on class numbers of every constant field extension of K_J=F_q(\sqrt[3]{(T-a)(T-b)}). Finally, we compute the exact values and the average values on Euler-Kronecker constants of K_J. This is a joint work with Jinjoo Yoo.

2024-09-30 / 10:30 ~ 11:30

SAARC 세미나 - SAARC 세미나:

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In this talk, we investigate some regularity results for non-uniformly elliptic problems. We first present uniformly elliptic problems and the definition of non-uniform ellipticity. We then introduce a double phase problem which is characterized by the fact that its ellipticity rate and growth radically change with the position. We show gradient Hölder continuity and Calderón-Zygmund type estimates for distributional solutions to double phase problems. We also consider double phase problems with two modulating coefficients.

2024-10-02 / 16:30 ~ 18:00

학과 세미나/콜로퀴엄 - 대수기하학:

by 정재우()

The study of monomial ideals is central to many areas of commutative algebra and algebraic geometry, with Stanley-Reisner theory providing a crucial bridge between algebraic invariants and combinatorial structures. We explore how the syzygies and Betti diagrams of Stanley-Reisner ideals can be understood through combinatorial operations on simplicial complexes. In this talk, we focus on the regularity of Stanley-Reisner ideals. We introduce a graph decomposition that bounds the regularity and a decomposition of simplicial complexes with respect to facets. In addition, we introduce secant complexes corresponding to the joins of varieties defined by Stanley-Reisner ideals and investigate the secant variety of minimal degree defined by the Stanley-Reisner ideals. This talk includes multiple collaborative works with G. Blekherman, J. Choe, J. Kim, M. Kim, and Y. Kim.

2024-09-26 / 11:50 ~ 12:40

대학원생 세미나 - 대학원생 세미나:

by 은남현()

In this talk, we will discuss the uniqueness and stability of a Riemann shock solution to the compressible Euler system, which is a self-similar entropy solution connecting two different constant states, in a physical vanishing viscosity limits. We focus on the one dimensional compressible full Euler system and consider the Brenner-Navier-Stokes-Fourier system, which is an amendment of the Navier-Stokes-Fourier system, to describe the physical perturbation class. (This is a joint work with Moon-Jin Kang (KAIST) and Saehoon Eo (Stanford University).

2024-10-02 / 16:00 ~ 17:00

SAARC 세미나 - SAARC 세미나:

by 류한백()

We study large random matrices with i.i.d. entries conditioned to have prescribed row and column sums (margin). This problem has rich connections to relative entropy minimization, Schrodinger bridge, the enumeration of contingency tables, and random graphs with given degree sequences. Such margin-constrained random matrix turns out to be sharply concentrated around a certain deterministic matrix, which we call the "typical table". Typical tables have dual characterizations: (1) the expectation of the random matrix ensemble with minimum relative entropy from the base model constrained to have the expected target margin, and (2) the expectation of the maximum likelihood model obtained by rank-one exponential tilting of the base model. The structure of the typical table is dictated by two dual variables, which give the maximum likelihood estimates of the tilting parameters. Based on these results, for a sequence of "tame" margins that converges in $L^{1}$ to a limiting continuum margin as the size of the matrix diverges, we show that the sequence of margin-constrained random matrices converges in cut norm to a limiting kernel, which is the $L^{2}$-limit of the corresponding rescaled typical tables. The rate of convergence is controlled by how fast the margins converge in $L^{1}$. We also propose a Sinkhorn-type alternating minimization algorithm for computing typical tables, which speicalizes to the classical Sinkhorn algorithm for the Poisson base measure. We derive several new results for random contingency tables from our general framework. This talk is based on a Joint work with Sumit Mukherjee (Columbia).

2024-10-02 / 13:30 ~ 14:30

학과 세미나/콜로퀴엄 - Topology, Geometry, and Data Analysis: Introduction to Graph Neural Networks (Part 3)

by 서동엽(KAIST)

2024-09-27 / 13:30 ~ 14:30

학과 세미나/콜로퀴엄 - Topology, Geometry, and Data Analysis: Introduction to Graph Neural Networks (Part 2)

by 서동엽(KAIST)

2024-09-26 / 16:15 ~ 17:15

학과 세미나/콜로퀴엄 - 콜로퀴엄:

by 조재현(UNIST 수리과학과)

First, we briefly introduce arithmetic statistics. After that we give some AS problems related to L-functions such as class numbers and analytic rank of elliptic curves.

2024-10-02 / 16:00 ~ 17:00

IBS-KAIST 세미나 - IBS-KAIST 세미나:

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The study of sleep and circadian rhythms at scale requires novel technologies and approaches that are valid, cost effective and do not pose much of a burden to the participant. Here we will present our recent studies in which we have evaluated several classes of technologies and approaches including wearables, nearables, blood based biomarkers and combinations of data with mathematical models.

2024-10-01 / 10:30 ~ 11:30

학과 세미나/콜로퀴엄 - 대수기하학:

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The lecture series gives a view on computational methods and their some applications to existence and classfication problems. In the first lectures I will introduce Groebner basis and their basic applications in commutative algebra such as computing kernel and images of morphism between finitely presented modules over polynomial rings. As a theoretical application of Groebner basis I will give Petri's analysis of the equations of a canonical curve. The second topic will be Computer aided existence and unirationality proofs of algebraic varieties and their moduli spaces. In case of curves liaison theory is needed, which will be developed. For existence proofs random searches over finite fields is a technique that has not been exploited very much. I will illustrate this technique in a number of examples, in particular for the construction of certain surfaces. Classification of non-minimal surfaces uses adjunction theory. We will discuss this from a computational point of view.

Events for the 취소된 행사 포함