Thursday, August 8, 2024

2024-08-14 / 15:00 ~ 16:00

SAARC 세미나 - SAARC 세미나:

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In this talk, we first review nonlinear elliptic equations when the right-hand side is a finite measure. We discuss global gradient estimates of a solution for such measure data problems in bounded nonsmooth domains. We provide proper solutions and conditions which guarantee the regularity results. If time permits, we will consider parabolic problems with measure data.

2024-08-08 / 16:00 ~ 17:00

편미분방정식 통합연구실 세미나 - 편미분방정식:

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We consider Calogero—Moser derivative NLS (CM-DNLS) equation which can be seen as a continuum version of completely integrable Calogero—Moser many-body systems in classical mechanics. Soliton resolution refers to the phenomenon where solutions asymptotically decompose into a sum of solitons and a dispersive radiation term as time progresses. Our work proves soliton resolution for both finite-time blow-up and global solutions without radial symmetry or size constraints. Although the equation exhibits integrability, our proof does not depend on this property, potentially providing insights applicable to other non-integrable models. This research is based on the joint work with Soonsik Kwon (KAIST).

2024-08-08 / 15:00 ~ 16:00

편미분방정식 통합연구실 세미나 - 편미분방정식:

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We consider the global dynamics of finite energy solutions to energy-critical equivariant harmonic map heat flow (HMHF). It is known that any finite energy equivariant solutions to (HMHF) decompose into finitely many harmonic maps (bubbles) separated by scales and a body map, as approaching to the maximal time of existence. Our main result for (HMHF) gives a complete classification of their dynamics for equivariance indices D≥3; (i) they exist globally in time, (ii) the number of bubbles and signs are determined by the energy class of the initial data, and (iii) the scales of bubbles are asymptotically given by a universal sequence of rates up to scaling symmetry. In parallel, we also obtain a complete classification of $\dot{H}^1$-bounded radial solutions to energy-critical heat equations in dimensions N≥7, building upon soliton resolution for such solutions. This is a joint work with Frank Merle (IHES and CY Cergy-Paris University).

2024-08-08 / 16:00 ~ 17:30

학과 세미나/콜로퀴엄 - 기타: Introduction to Milnor K-theory 6: proof of Suslin reciprocity and reinterpretation of Gauss quadratic reciprocity

by 사킵 무쉬타크 샤(Indian Statistical Institute - Bangalore)

Mr. Saqib Mushtaq Shah, a KAIX visiting graduate student from ISI Bangalore who will stay at KAIST for 8 weeks, is going to give a series of weekly talks on the Milnor K-theory from the beginning. It is part of his KAIX summer internship works.

2024-08-14 / 16:30 ~ 17:30

학과 세미나/콜로퀴엄 - 정수론:

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As part of the Langlands conjecture, it is predicted that every $\ell$-adic Galois representation attached to an algebraic cuspidal automorphic representation of $\mathrm{GL}_n$ over a number field is irreducible. In this talk, we will prove that a type $A_1$ Galois representation attached to a regular algebraic (polarized) cuspidal automorphic representation of $\mathrm{GL}_n$ over a totally real field $K$ is irreducible for all $\ell$, subject to some mild conditions. We will also prove that the attached Galois representation is residually irreducible for almost all $\ell$. Moreover, if $K=\mathbb Q$, we will prove that the attached Galois representation can be constructed from two-dimensional modular Galois representations up to twist. This is a joint work with Professor Chun-Yin Hui.

2024-08-13 / 16:30 ~ 17:30

IBS-KAIST 세미나 - 이산수학: Formalizing matroid theory in a proof assistant

by Peter Nelson(University of Waterloo)

For the past few years, I’ve been working on formalizing proofs in matroid theory using the Lean proof assistant. This has led me to many interesting and unexpected places. I’ll talk about what formalization looks like in practice from the perspective of a combinatorialist.

2024-08-14 / 14:00 ~ 16:00

학과 세미나/콜로퀴엄 - 위상수학 세미나:

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Let S be a simply-connected rational homology complex projective plane with quotient singularities. The algebraic Montgomery-Yang problem conjectures that the number of singular points of S is at most three. In this talk, we leverage results from the study of smooth 4-manifolds, such as the Donaldson diagonalization theorem, to establish additional conditions for S. As a result, we eliminate the possibility of a rational homology complex projective plane of specific types with four singularities. We also identify infinite families of singularities that satisfy properties in algebraic geometry, including the orbifold BMY inequality, but are obstructed from being a rational homology complex projective plane due to smooth conditions. Additionally, we discuss experimental results related to this problem. This is joint work with Jongil Park and Kyungbae Park.

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