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PRODID:-//Discrete Mathematics Group - ECPv6.16.2//NONSGML v1.0//EN
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METHOD:PUBLISH
X-ORIGINAL-URL:https://dimag.ibs.re.kr
X-WR-CALDESC:Events for Discrete Mathematics Group
REFRESH-INTERVAL;VALUE=DURATION:PT1H
X-Robots-Tag:noindex
X-PUBLISHED-TTL:PT1H
BEGIN:VTIMEZONE
TZID:Asia/Seoul
BEGIN:STANDARD
TZOFFSETFROM:+0900
TZOFFSETTO:+0900
TZNAME:KST
DTSTART:20250101T000000
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BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20260609T163000
DTEND;TZID=Asia/Seoul:20260609T173000
DTSTAMP:20260516T043205
CREATED:20260122T084352Z
LAST-MODIFIED:20260122T084352Z
UID:12117-1781022600-1781026200@dimag.ibs.re.kr
SUMMARY:Martin Milanič\, TBA
DESCRIPTION:
URL:https://dimag.ibs.re.kr/event/2026-06-09/
LOCATION:Room B332\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20260616T163000
DTEND;TZID=Asia/Seoul:20260616T173000
DTSTAMP:20260516T043205
CREATED:20260420T212857Z
LAST-MODIFIED:20260420T212857Z
UID:12560-1781627400-1781631000@dimag.ibs.re.kr
SUMMARY:J. Pascal Gollin\, TBA
DESCRIPTION:
URL:https://dimag.ibs.re.kr/event/2026-06-16/
LOCATION:Room B332\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20260619T163000
DTEND;TZID=Asia/Seoul:20260619T173000
DTSTAMP:20260516T043205
CREATED:20260515T123736Z
LAST-MODIFIED:20260515T123736Z
UID:12649-1781886600-1781890200@dimag.ibs.re.kr
SUMMARY:Stefan Weltge\, Multiplicative assignment with upgrades
DESCRIPTION:We study a problem related to submodular function optimization and the exact matching problem for which we show a rather peculiar status: its natural LP-relaxation can have fractional optimal vertices\, but there is always also an optimal integral vertex\, which we can also compute in polynomial time. More specifically\, we consider the multiplicative assignment problem with upgrades in which we are given a set of customers and suppliers and we seek to assign each customer to a different supplier. Each customer has a demand and each supplier has a regular and an upgraded cost for each unit demand provided to the respective assigned client. Our goal is to upgrade at most k suppliers and to compute an assignment in order to minimize the total resulting cost. This can be cast as the problem to compute an optimal matching in a bipartite graph with the additional constraint that we must select k edges from a certain group of edges\, similar to selecting k red edges in the exact matching problem. Also\, selecting the suppliers to be upgraded corresponds to maximizing a submodular set function under a cardinality constraint. Our result yields an efficient LP-based algorithm to solve our problem optimally. In addition\, we provide also a purely strongly polynomial-time algorithm for it. As an application\, we obtain exact algorithms for the upgrading variant of the problem to schedule jobs on identical or uniformly related machines in order to minimize their sum of completion times\, i.e.\, where we may upgrade up to k jobs to reduce their respective processing times. \nThis is joint work with Alexander Armbruster\, Lars Rohwedder\, Andreas Wiese\, and Ruilong Zhang.
URL:https://dimag.ibs.re.kr/event/2026-06-19/
LOCATION:Room B332\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;VALUE=DATE:20260628
DTEND;VALUE=DATE:20260712
DTSTAMP:20260516T043205
CREATED:20260415T104127Z
LAST-MODIFIED:20260415T104444Z
UID:12537-1782604800-1783814399@dimag.ibs.re.kr
SUMMARY:2026 Workshop on Topological Combinatorics
DESCRIPTION:The 2026 Workshop on Topological Combinatorics will be held from June 28 to July 11\, 2026 at Gwangju Institute of Science and Technology (GIST)\, located in Gwangju in the southwest of Republic of Korea.  \nThe workshop aims to bring together researchers interested in applications of topology to combinatorics and related areas. This will be the fifth workshop in a series initiated by Ron Aharoni (August 2018 in Shantou\, July 2019 in Prague\, July 2020 on Zoom\, and June 2024 in Paris). \nThe first week (June 28 – July 04) will be reserved for presentations\, while the following days (July 05 – July 11) will be for discussion and collaborations.  \nThe campus offers a variety of amenities\, including a guesthouse that can accommodate approximately 20 guests. \nIn addition\, various lodging options are available within a 15–20 minute walking distance. \nWe are planning to provide accommodation for all invited participants\, and we are also considering offering partial travel support for those with limited funding. \n\nWebsite: https://sites.google.com/view/2026topocomb
URL:https://dimag.ibs.re.kr/event/2026-06-28/
LOCATION:GIST
CATEGORIES:Workshops and Conferences
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20260710T163000
DTEND;TZID=Asia/Seoul:20260710T173000
DTSTAMP:20260516T043205
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;VALUE=DATE:20260727
DTEND;VALUE=DATE:20260801
DTSTAMP:20260516T043205
CREATED:20260415T104353Z
LAST-MODIFIED:20260415T104353Z
UID:12545-1785110400-1785542399@dimag.ibs.re.kr
SUMMARY:2026 Korean Student Combinatorics Workshop
DESCRIPTION:Website: https://kscw.combinatorics.kr/
URL:https://dimag.ibs.re.kr/event/2026-07-27/
LOCATION:Gongju Hanok Village\, Gongju
CATEGORIES:Workshops and Conferences
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20260818T163000
DTEND;TZID=Asia/Seoul:20260818T173000
DTSTAMP:20260516T043205
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
END:VEVENT
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