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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:20261006T163000
DTEND;TZID=Asia/Seoul:20261006T173000
DTSTAMP:20260821T005558Z
CREATED:20260821T005539Z
LAST-MODIFIED:20260821T005558Z
UID:13133-1791304200-1791307800@dimag.ibs.re.kr
SUMMARY:Daniel McGinnis\, Multi-generic initial ideals\, regularity\, and the optimal colorful fractional Helly theorem for $d$-Leray complexes
DESCRIPTION:A celebrated result of Bayer and Stillman from 1987 states that for a homogeneous ideal $I$ of a polynomial ring $S$\, the regularities of $S/I$ and $S/\textrm{GIN}(I)$ are the same under the reverse lexicographic monomial ordering\, where $\textrm{GIN}(I)$ is the generic initial ideal. If $R$ is a polynomial ring whose variables are subdivided into disjoint blocks of variables $X_1\,\dots\,X_c$\, there is a natural multi-grading on $R$\, and one can analogously define a multi-graded version of the generic initial ideal for any multi-homogeneous ideal $I$ of $R$. However\, the full strength of the Bayer-Stillman Theorem fails in the multi-graded setting; there are multi-homogeneous ideals $I$ such that the regularities are not preserved after passing to the multi-graded generic initial ideal no matter the choice of monomial ordering. \nWe prove lower bounds on the regularity of $R/I$ in terms of almost regular sequences of the multi-graded generic initial ideal of $I$ restricted to each block of variables. Again\, we use the reverse lexicographic monomial ordering\, but interestingly\, the lower bound result requires a particular choice of ordering on the variables. \nAs an application\, we prove the optimal fractional Helly theorem for $d$-Leray simplicial complexes\, a problem stemming from the work of Kim in 2017.
URL:https://dimag.ibs.re.kr/event/2026-10-06/
LOCATION:Room B332\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
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DTSTART;TZID=Asia/Seoul:20261013T163000
DTEND;TZID=Asia/Seoul:20261013T173000
DTSTAMP:20260819T090026Z
CREATED:20260811T214705Z
LAST-MODIFIED:20260819T090026Z
UID:13078-1791909000-1791912600@dimag.ibs.re.kr
SUMMARY:Julien Codsi\, Recent progress in the tree-⍺ world
DESCRIPTION:Treewidth is a graph parameter commonly used to quantify how “close” a graph is to a tree. Although it is a cornerstone of structural graph theory and algorithm design\, it is nearly useless for algorithmic purposes in many dense graph classes. In this talk\, we discuss the tree-independence number\, a more versatile graph parameter that replaces the standard width measure with the stability number. We will present recent results aimed at characterizing the graph classes in which this parameter enables sub-exponential time algorithms for problems that are\, in general\, NP-hard.
URL:https://dimag.ibs.re.kr/event/2026-10-13/
LOCATION:Room B332\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
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BEGIN:VEVENT
DTSTART;VALUE=DATE:20261020
DTEND;VALUE=DATE:20261023
DTSTAMP:20260702T064849Z
CREATED:20260611T134208Z
LAST-MODIFIED:20260702T064849Z
UID:12748-1792454400-1792713599@dimag.ibs.re.kr
SUMMARY:2026 Combinatorics Workshop (2026 조합론 학술대회)
DESCRIPTION:Combinatorics Workshop (조합론 학술대회) is an annual conference for researchers in combinatorics and related areas in Korea. It was started in 2004 by the Yonsei University BK21 Research Group. Since 2013\, this workshop has been advised by the committee of discrete mathematics of the Korean Mathematical Society. \nWebsite: https://cw2026.combinatorics.kr/en/ \nVenue\nKonjiam Resort\, EW Village\, B2\, Meeting Room OPUS2 \n(278\, Docheogwit-Ro\, Docheok-Myeon\, Gwangju-Si\, Gyeonggi-Do\, Korea) \n\nTravel Instructions\n\nDates\nOctober 20 to 22\, 2026 \nPlenary Speaker\nAlexander V. Kostochka (UIUC) \nInvited Speakers\n\nCheolwon Heo (SUNY Korea)\nTony Huynh (IBS DIMAG)\nDabeen Lee (Seoul National University)\nJongbaek Song (Pusan National University)\n\nContributed Talks\nEach contributed talk will be about 20 minutes\, including questions. Please note that we may stop accepting contributed talk applications before the deadline if all available slots are filled. \nIf you are interested in giving a contributed talk at the workshop\, please submit an abstract by August 31\, 2026. \nTo apply for a contributed talk\, go to Call for Abstracts on Indico and click “Submit new abstract.” You may need to create an IBS Indico account. \nRegistration\nRegistration link \nThe registration deadline is August 31\, 2026. \nOrganizing Committee\n\nIlkyoo Choi (최일규)\, Hankuk University of Foreign Studies\, IBS Discrete Mathematics Group\, KIAS\nSang-il Oum (엄상일)\, IBS Discrete Mathematics Group\nBoram Park (박보람)\, Seoul National University\n\nAdvisory Committee\nCommittee of Discrete Mathematics\, The Korean Mathematical Society (Chair: Sang-il Oum) \nSponsors\n\nIBS Discrete Mathematics Group\nKorean Mathematical Society\nSeoul National University\nHankuk University of Foreign Studies
URL:https://dimag.ibs.re.kr/event/2026-combinatorics-workshop/
LOCATION:Konjiam Resort\, EW Village\, B2\, Meeting Room OPUS2
CATEGORIES:Workshops and Conferences
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