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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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DTSTART:20200101T000000
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BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20210113T100000
DTEND;TZID=Asia/Seoul:20210113T110000
DTSTAMP:20260422T214905
CREATED:20201126T045239Z
LAST-MODIFIED:20240705T192124Z
UID:3318-1610532000-1610535600@dimag.ibs.re.kr
SUMMARY:Rose McCarty\, Vertex-minors and flooding immersions
DESCRIPTION:An immersion of a graph H into a graph G sends edges of H into edge-disjoint trails of G. We say the immersion is flooding if every edge of G is in one of the trails. Flooding immersions are interesting for Eulerian group-labelled graphs; in this context they behave quite differently from regular immersions. Moreover\, understanding such flooding immersions is a vital step towards understanding the structure of graphs with a forbidden vertex-minor. \nI will focus on explaining the connection to vertex-minors\, and on recent progress in this direction from ongoing joint work with Jim Geelen and Paul Wollan.
URL:https://dimag.ibs.re.kr/event/2021-01-13/
LOCATION:Zoom ID: 869 4632 6610 (ibsdimag)
CATEGORIES:Virtual Discrete Math Colloquium
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BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20210120T163000
DTEND;TZID=Asia/Seoul:20210120T173000
DTSTAMP:20260422T214905
CREATED:20201211T084524Z
LAST-MODIFIED:20240707T081951Z
UID:3358-1611160200-1611163800@dimag.ibs.re.kr
SUMMARY:Yusuke Kobayashi (小林 佑輔)\, An FPT Algorithm for Minimum Additive Spanner Problem
DESCRIPTION:For a positive integer t and a graph G\, an additive t-spanner of G is a spanning subgraph in which the distance between every pair of vertices is at most the original distance plus t. Minimum Additive t-Spanner Problem is to find an additive t-spanner with the minimum number of edges in a given graph\, which is known to be NP-hard. Since we need to care about global properties of graphs when we deal with additive t-spanners\, Minimum Additive t-Spanner Problem is hard to handle\, and hence only few results are known for it. In this talk\, we study Minimum Additive t-Spanner Problem from the viewpoint of parameterized complexity. We formulate a parameterized version of the problem in which the number of removed edges is regarded as a parameter\, and give a fixed-parameter algorithm for it. We also extend our result to (α\,β)-spanners.
URL:https://dimag.ibs.re.kr/event/2021-01-20/
LOCATION:Zoom ID: 869 4632 6610 (ibsdimag)
CATEGORIES:Virtual Discrete Math Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20210127T100000
DTEND;TZID=Asia/Seoul:20210127T110000
DTSTAMP:20260422T214905
CREATED:20210114T124234Z
LAST-MODIFIED:20240705T191135Z
UID:3500-1611741600-1611745200@dimag.ibs.re.kr
SUMMARY:Dong Yeap Kang (강동엽)\, A proof of the Erdős-Faber-Lovász conjecture
DESCRIPTION:A hypergraph is linear if every pair of two distinct edges shares at most one vertex. A longstanding conjecture by Erdős\, Faber\, and Lovász in 1972\, states that the chromatic index of any linear hypergraph on $n$ vertices is at most $n$. \nIn this talk\, I will present the ideas to prove the conjecture for all large $n$. This is joint work with Tom Kelly\, Daniela Kühn\, Abhishek Methuku\, and Deryk Osthus.
URL:https://dimag.ibs.re.kr/event/2021-01-27/
LOCATION:Zoom ID: 869 4632 6610 (ibsdimag)
CATEGORIES:Virtual Discrete Math Colloquium
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