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PRODID:-//Discrete Mathematics Group - ECPv6.15.20//NONSGML v1.0//EN
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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
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:20170101T000000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20190103T160000
DTEND;TZID=Asia/Seoul:20190103T170000
DTSTAMP:20260419T201218
CREATED:20181224T085518Z
LAST-MODIFIED:20240707T090650Z
UID:305-1546531200-1546534800@dimag.ibs.re.kr
SUMMARY:Joonkyung Lee (이준경)\, Sidorenko’s conjecture for blow-ups
DESCRIPTION:A celebrated conjecture of Sidorenko and Erdős–Simonovits states that\, for all bipartite graphs H\, quasirandom graphs contain asymptotically the minimum number of copies of H taken over all graphs with the same order and edge density. This conjecture has attracted considerable interest over the last decade and is now known to hold for a broad range of bipartite graphs\, with the overall trend saying that a graph satisfies the conjecture if it can be built from simple building blocks such as trees in a certain recursive fashion. \nOur contribution here\, which goes beyond this paradigm\, is to show that the conjecture holds for any bipartite graph H with bipartition A∪B where the number of vertices in B of degree k satisfies a certain divisibility condition for each k. As a corollary\, we have that for every bipartite graph H with bipartition A∪B\, there is a positive integer p such that the blow-up HAp formed by taking p vertex-disjoint copies of H and gluing all copies of A along corresponding vertices satisfies the conjecture. Joint work with David Conlon.
URL:https://dimag.ibs.re.kr/event/2019-01-03/
LOCATION:Room B232\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20181213T170000
DTEND;TZID=Asia/Seoul:20181213T180000
DTSTAMP:20260419T201218
CREATED:20181120T125609Z
LAST-MODIFIED:20240707T090704Z
UID:250-1544720400-1544724000@dimag.ibs.re.kr
SUMMARY:Hong Liu\, Polynomial Schur’s Theorem
DESCRIPTION:I will discuss the Ramsey problem for {x\,y\,z:x+y=p(z)} for polynomials p over ℤ. This is joint work with Peter Pach and Csaba Sandor.
URL:https://dimag.ibs.re.kr/event/2018-12-13/
LOCATION:Room B109\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20181210T170000
DTEND;TZID=Asia/Seoul:20181210T180000
DTSTAMP:20260419T201218
CREATED:20181031T151146Z
LAST-MODIFIED:20240707T090718Z
UID:180-1544461200-1544464800@dimag.ibs.re.kr
SUMMARY:Tony Huynh\, A tight Erdős-Pósa function for planar minors
DESCRIPTION:Let H be a planar graph. By a classical result of Robertson and Seymour\, there is a function f(k) such that for all k and all graphs G\, either G contains k vertex-disjoint subgraphs each containing H as a minor\, or there is a subset X of at most f(k) vertices such that G−X has no H-minor. We prove that this remains true with f(k)=ck log k for some constant c depending on H. This bound is best possible\, up to the value of c\, and improves upon a recent bound of Chekuri and Chuzhoy. The proof is constructive and yields the first polynomial-time O(log 𝖮𝖯𝖳)-approximation algorithm for packing subgraphs containing an H-minor. \nThis is joint work with Wouter Cames van Batenburg\, Gwenaël Joret\, and Jean-Florent Raymond.
URL:https://dimag.ibs.re.kr/event/2018-12-10/
LOCATION:Room B109\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
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