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X-WR-CALNAME:Discrete Mathematics Group
X-ORIGINAL-URL:https://dimag.ibs.re.kr
X-WR-CALDESC:Events for Discrete Mathematics Group
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TZID:Asia/Seoul
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TZOFFSETFROM:+0900
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DTSTART:20250101T000000
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BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20260619T163000
DTEND;TZID=Asia/Seoul:20260619T173000
DTSTAMP:20260610T203503
CREATED:20260515T123736Z
LAST-MODIFIED:20260610T004840Z
UID:12649-1781886600-1781890200@dimag.ibs.re.kr
SUMMARY:Stefan Weltge\, The relaxation complexity of the standard simplex is logarithmic
DESCRIPTION:For a set $X$ of integer points\, the relaxation complexity $\operatorname{rc}(X)$ is the smallest number of facets of any polyhedron P whose integer points are precisely those of X. In this paper\, we focus on the case where X is the discrete standard simplex $\Delta_d = \{0\, e_1\, …\, e_d\}$. We show that $\operatorname{rc}(\Delta_d) = O(\log d)$ by an explicit\, elementary construction. This improves upon the previously best-known upper bound $\operatorname{rc}(\Delta_d) = O(d / \sqrt{\log d})$ due to Aprile\, Averkov\, Di Summa\, and Hojny (2022) and matches an asymptotic lower bound by Averkov and Schymura (2020). This is joint work with Simon Keil.
URL:https://dimag.ibs.re.kr/event/2026-06-19/
LOCATION:Room B332\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20260710T163000
DTEND;TZID=Asia/Seoul:20260710T173000
DTSTAMP:20260610T203503
CREATED:20260324T141000Z
LAST-MODIFIED:20260505T064804Z
UID:12471-1783701000-1783704600@dimag.ibs.re.kr
SUMMARY:Ting-Wei Chao\, The Oddtown Problem Modulo a Composite Number
DESCRIPTION:A family of sets in $[n]$ is called an $\ell$-Oddtown if the sizes of all sets are not divisible by $\ell$\, but the sizes of pairwise intersections are divisible by $\ell$. The problem was completely solved when $\ell$ is a prime via an elegant linear algebraic method\, showing that the family has size at most $n$. However\, not much was known for composite numbers. By splitting the family into families correspond to each prime factor of $\ell$\, one can show that the number is at most $\omega n$\, where $omega$ is the number of prime factors of $\ell$. We used both combinatorial and Fourier analytic arguments to prove that the number of sets in any $\ell$-Oddtown is at most $\omega n-(2\omega+\varepsilon)\log_2 n$ for most $n\,\ell$.
URL:https://dimag.ibs.re.kr/event/2026-07-10/
LOCATION:Room B332\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20260805T163000
DTEND;TZID=Asia/Seoul:20260805T173000
DTSTAMP:20260610T203503
CREATED:20260520T141609Z
LAST-MODIFIED:20260520T141609Z
UID:12683-1785947400-1785951000@dimag.ibs.re.kr
SUMMARY:Meike Hatzel\, TBA
DESCRIPTION:
URL:https://dimag.ibs.re.kr/event/2026-08-05/
LOCATION:Room B332\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20260818T163000
DTEND;TZID=Asia/Seoul:20260818T173000
DTSTAMP:20260610T203503
CREATED:20260326T020259Z
LAST-MODIFIED:20260326T020259Z
UID:12486-1787070600-1787074200@dimag.ibs.re.kr
SUMMARY:Jinyoung Park (박진영)\, TBA
DESCRIPTION:
URL:https://dimag.ibs.re.kr/event/2026-08-18/
LOCATION:Room B332\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
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