BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Discrete Mathematics Group - ECPv6.15.20//NONSGML v1.0//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
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:20190101T000000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20200804T163000
DTEND;TZID=Asia/Seoul:20200804T173000
DTSTAMP:20260424T063547
CREATED:20200708T124259Z
LAST-MODIFIED:20240705T200010Z
UID:2626-1596558600-1596562200@dimag.ibs.re.kr
SUMMARY:June Huh (허준이)\, Kazhdan-Lusztig polynomials of graphs and matroids
DESCRIPTION:I will introduce Kazhdan-Lusztig polynomials of matroids and survey combinatorial and geometric theories built around them. The focus will be on the conjecture of Gedeon\, Proudfoot\, and Young that all zeros of the Kazhdan-Lusztig polynomial of a matroid lie on the negative real axis.
URL:https://dimag.ibs.re.kr/event/2020-08-04/
LOCATION:Room B232\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20200805T163000
DTEND;TZID=Asia/Seoul:20200805T173000
DTSTAMP:20260424T063547
CREATED:20200629T004613Z
LAST-MODIFIED:20240705T200032Z
UID:2570-1596645000-1596648600@dimag.ibs.re.kr
SUMMARY:Robert Ganian\, Solving Integer Linear Programs by Exploiting Variable-Constraint Interactions
DESCRIPTION:Integer Linear Programming (ILP) is among the most successful and general paradigms for solving computationally intractable optimization problems in computer science. ILP is NP-complete\, and until recently we have lacked a systematic study of the complexity of ILP through the lens of variable-constraint interactions. This changed drastically in recent years thanks to a series of results that together lay out a detailed complexity landscape for the problem centered around the structure of graphical representations of instances. The aim of this talk is to summarize these recent developments and put them into context. Special attention will be paid to the structural parameter treedepth\, and at the end of the talk we will also consider how treedepth can be used to design algorithms for problems beyond ILP.
URL:https://dimag.ibs.re.kr/event/2020-08-05/
LOCATION:Zoom ID: 869 4632 6610 (ibsdimag)
CATEGORIES:Virtual Discrete Math Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;VALUE=DATE:20200810
DTEND;VALUE=DATE:20200814
DTSTAMP:20260424T063547
CREATED:20200221T012853Z
LAST-MODIFIED:20240705T201209Z
UID:2145-1597017600-1597363199@dimag.ibs.re.kr
SUMMARY:Nonlinear Algebra in Daejeon (Postponed)
DESCRIPTION:Program\n\nSummer School @ KAIST (August 4-7\, 2020)\nDiscussion Weekend (August 8-9\, 2020)\nWorkshop @ IBS Science Culture Center (August 10-13\, 2020)\n\nWebsite: https://dimag.ibs.re.kr/home/nonlinear/ \nOrganizing Committee\n\nInsong Choe (Konkuk U.)\nKangjin Han (DGIST)\nDavid Hyeon (SNU)\nSijong Kwak (KAIST)\nYongnam Lee (KAIST)\nAnton Leykin (Georgia Tech)\nSang-il Oum (IBS & KAIST)\nFrank Sottile (TAMU)
URL:https://dimag.ibs.re.kr/event/nonlinear-algebra-in-daejeon/
LOCATION:IBS Science Culture Center
CATEGORIES:Workshops and Conferences
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20200811T163000
DTEND;TZID=Asia/Seoul:20200811T173000
DTSTAMP:20260424T063547
CREATED:20200725T052636Z
LAST-MODIFIED:20240707T082925Z
UID:2708-1597163400-1597167000@dimag.ibs.re.kr
SUMMARY:Yunbum Kook (국윤범)\, Vertex Sparsification for Edge Connectivity
DESCRIPTION:Graph compression or sparsification is a basic information-theoretic and computational question. A major open problem in this research area is whether $(1+\epsilon)$-approximate cut-preserving vertex sparsifiers with size close to the number of terminals exist. As a step towards this goal\, we initiate the study of a thresholded version of the problem: for a given parameter $c$\, find a smaller graph\, which we call connectivity-$c$ mimicking network\, which preserves connectivity among $k$ terminals exactly up to the value of $c$. We show that contraction-based connectivity-$c$ mimicking networks with $O(kc^4)$ edges exist by (1) introducing an extension of well-linkedness to a thresholded $c$-connectivity setting and (2) leveraging a kernelization result\, based on gammoid and the representative sets lemma\, to identify `essential edges’ in minimum edge cuts between a partition of terminals. We also develop an algorithm based on expander decomposition\, which can find a contraction-based $c$-mimicking network of the optimal size in $m(c\log n)^{O(c)}$. \nThese results lead to the first data structures for answering fully dynamic offline $c$-edge-connectivity queries for $c \ge 4$ in polylogarithmic time per query\, as well as more efficient algorithms for survivable network design on bounded treewidth graphs. \nThis is a joint work with Parinya Chalermsook\, Syamantak Das\, Bundit Laekhanukit\, Yang P. Liu\, Richard Peng\, Mark Sellke\, and Daniel Vaz.
URL:https://dimag.ibs.re.kr/event/2020-08-11/
LOCATION:Room B232\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20200818T163000
DTEND;TZID=Asia/Seoul:20200818T173000
DTSTAMP:20260424T063547
CREATED:20200804T124550Z
LAST-MODIFIED:20240707T082915Z
UID:2750-1597768200-1597771800@dimag.ibs.re.kr
SUMMARY:Tuan Tran\, Anti-concentration phenomena
DESCRIPTION:Let $X$ be a real random variable; a typical anti-concentration inequality asserts that (under certain assumptions) if an interval $I$ has small length\, then $\mathbb{P}(X\in I)$ is small\, regardless the location of $I$. Inequalities of this type have found powerful applications in many branches of mathematics. In this talk we will discuss several recent applications of anti-concentration inequalities in extremal combinatorics\, as well as random matrix theory. The talk is partially based on joint work with Matthew Kwan and Benny Sudakov.
URL:https://dimag.ibs.re.kr/event/2020-08-18/
LOCATION:Room B232\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20200819T163000
DTEND;TZID=Asia/Seoul:20200819T173000
DTSTAMP:20260424T063547
CREATED:20200629T004729Z
LAST-MODIFIED:20240705T200030Z
UID:2573-1597854600-1597858200@dimag.ibs.re.kr
SUMMARY:Gwenaël Joret\, Packing and covering balls in graphs excluding a minor
DESCRIPTION:In 2007\, Chepoi\, Estellon\, and Vaxès conjectured that there exists a universal constant $c>0$ such that the following holds for every positive integers $r$ and $k$\, and every planar graph $G$: Either $G$ contains $k$ vertex-disjoint balls of radius $r$\, or there is a subset of vertices of size at most $c k$ meeting all balls of radius $r$ in $G$. The key aspect of this conjecture is that the constant $c$ does not depend on the radius $r$ of the balls. If we were to allow this dependency\, then the statement is known to hold\, and in fact it is true in the more general setting of graph classes with bounded expansion (as proved by Dvořák). \nIn this talk I will present a proof of this conjecture. The result we prove is a bit more general: (1) The conjecture holds for every proper minor-closed class of graphs (with the constant $c$ depending on the class)\, and (2) we can even focus on any set of balls in the graph we like\, there is nothing special about taking all balls of a given radius. In other words\, we show that for every proper minor-closed class $C$ of graphs\, there exists a constant $c>0$ such that for every graph $G$ in $C$\, every set $S$ of balls in $G$\, and every positive integer $k$\, either there are $k$ vertex-disjoint balls in $S$\, or there is a subset of vertices of $G$ of size at most $c k$ meeting all balls in $S$. \nJoint work with Nicolas Bousquet\, Wouter Cames van Batenburg\, Louis\nEsperet\, William Lochet\, Carole Muller\, and François Pirot.
URL:https://dimag.ibs.re.kr/event/2020-08-19/
LOCATION:Zoom ID: 869 4632 6610 (ibsdimag)
CATEGORIES:Virtual Discrete Math Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;VALUE=DATE:20200824
DTEND;VALUE=DATE:20200825
DTSTAMP:20260424T063547
CREATED:20200804T150044Z
LAST-MODIFIED:20240705T195125Z
UID:2758-1598227200-1598313599@dimag.ibs.re.kr
SUMMARY:2020 Combinatorics Workshop
DESCRIPTION:Combinatorics Workshop (조합론 학술대회) is the biggest annual conference in combinatorics in Korea. It was firstly held in 2004 by the Yonsei University BK21 Research Group. It has been advised by the committee of discrete mathematics of the Korean Mathematical Society since 2013. The aim of this workshop is to bring active researchers with different backgrounds to discuss recent and prospective advances in combinatorics and related areas. \nOriginally\, we planned an offline workshop. However\, COVID 19 is more spreading and many participants are worried about attending an offline conference. So the schedule and venue are changed as an online workshop with Zoom. I hope that all participants generously understand this sudden change. \nInvited Speakers\n\nSejeong Bang (방세정)\, Yeungnam University\nRingi Kim (김린기)\, KAIST\nSangwook Kim (김상욱)\, Chonnam National University\nJinyoung Park (박진영)\, Institute for Advanced Study\nJongyook Park (박종육)\, Kyungpook N. University\n\nContributed speakers\n\nByung-Hak Hwang (황병학)\, Seoul National University\nJaeseong Oh (오재성)\, Seoul National University\nJun Seok Oh (오준석)\, Incheon National University\nTuan Tran\, Institute for Basic Science (IBS)\n\nMore information is available on the website https://cw2020.combinatorics.kr.
URL:https://dimag.ibs.re.kr/event/2020-combinatorics-workshop/
LOCATION:Zoom ID: 869 4632 6610 (ibsdimag)
CATEGORIES:Workshops and Conferences
END:VEVENT
BEGIN:VEVENT
DTSTART;VALUE=DATE:20200824
DTEND;VALUE=DATE:20200829
DTSTAMP:20260424T063547
CREATED:20191122T084127Z
LAST-MODIFIED:20240705T203020Z
UID:1878-1598227200-1598659199@dimag.ibs.re.kr
SUMMARY:2020 IBS Workshop on Extremal and Probabilistic Combinatorics (postponed)
DESCRIPTION:Date\nAugust 24\, 2020 – August 28\, 2020 \nArrival: August 23 Sunday. Departure: August 29\, Saturday \nVenue\nInstitute for Basic Science\,  55 Expo-ro\, Yuseong-gu\, Daejeon\, South Korea \nInvited Speakers\n\nJulia Böttcher\, London School of Economics\nBoris Bukh\, Carnegie Mellon University\nAmin Coja-Oghlan\, Goethe University\nDavid Conlon\, Caltech\nPenny Haxell\, University of Waterloo\nHao Huang\, Emory University\nJeff Kahn\, Rutgers University\nAlexandr V. Kostochka\, University of Illinois at Urbana-Champaign\nMichael Krivelevich\, Tel-Aviv University\nMichał Karoński\, Adam Mickiewicz University in Poznań\nAnita Liebenau\, UNSW Sydney\nHong Liu\, University of Warwick\nTomasz Łuczak\, Adam Mickiewicz University in Poznań\nRichard Montgomery\, University of Birmingham\nTobias Müller\, Groningen University\nPéter Pál Pach\, Budapest University of Technology and Economics\nMathias Schacht\, University of Hamburg\nAsaf Shapira\, Tel-Aviv University\nJoel Spencer\, New York University\nVan Vu\, Yale University\nYufei Zhao\, MIT\nThis list is incomplete. It is subject to change.\n\nAccommodation\nLotte City Hotel and Hotel ICC are within 700m. Invited speakers will be provided an accommodation at the near-by hotels. \nOrganizers\n\nMihyun Kang\, Graz University of Technology\, Austria.\nJaehoon Kim\, KAIST\, Korea.\nSang-il Oum\, IBS Discrete Mathematics Group\, Korea and KAIST\, Korea.
URL:https://dimag.ibs.re.kr/event/2020-ibs-workshop/
LOCATION:Room B234\, IBS (기초과학연구원)
CATEGORIES:Workshops and Conferences
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20200825T163000
DTEND;TZID=Asia/Seoul:20200825T173000
DTSTAMP:20260424T063547
CREATED:20200816T234618Z
LAST-MODIFIED:20240707T082841Z
UID:2794-1598373000-1598376600@dimag.ibs.re.kr
SUMMARY:Ben Lund\, Point-plane incidence bounds
DESCRIPTION:In the early 1980s\, Beck proved that\, if P is a set of n points in the real plane\, and no more than g points of P lie on any single line\, then there are $\Omega(n(n-g))$ lines that each contain at least 2 points of P. In 2016\, I found a generalization of this theorem\, giving a similar lower bound on the number of planes spanned by a set of points in real space. I will discuss this result\, along with a number of applications and related open problems.
URL:https://dimag.ibs.re.kr/event/2020-08-25/
LOCATION:Room B232\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20200826T103000
DTEND;TZID=Asia/Seoul:20200826T113000
DTSTAMP:20260424T063547
CREATED:20200629T004929Z
LAST-MODIFIED:20240705T200027Z
UID:2576-1598437800-1598441400@dimag.ibs.re.kr
SUMMARY:Nick Brettell\, On the graph width parameter mim-width
DESCRIPTION:Maximum induced matching width\, also known as mim-width\, is a width parameter for graphs introduced by Vatshelle in 2012.  This parameter can be defined over branch decompositions of a graph G\, where the width of a vertex partition (X\,Y) in G is the size of a maximum induced matching in the bipartite graph induced by edges of G with one endpoint in X and one endpoint in Y.  In this talk\, I will present a quick overview of mim-width and some key results that highlight why this parameter is of interest from both a theoretical and algorithmic point of view.  I will discuss some recent work regarding the boundedness or unboundedness of mim-width for hereditary classes defined by forbidding one or two induced subgraphs\, and for generalisations of convex graphs.  I will also touch on some interesting applications of this work\, in particular for colouring and list-colouring.  This is joint work with Jake Horsfield\, Andrea Munaro\, Giacomo Paesani\, and Daniel Paulusma.
URL:https://dimag.ibs.re.kr/event/2020-08-26/
LOCATION:Zoom ID: 869 4632 6610 (ibsdimag)
CATEGORIES:Virtual Discrete Math Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20200831T150000
DTEND;TZID=Asia/Seoul:20200831T160000
DTSTAMP:20260424T063547
CREATED:20200825T130214Z
LAST-MODIFIED:20240707T082829Z
UID:2848-1598886000-1598889600@dimag.ibs.re.kr
SUMMARY:Junguk Lee (이정욱)\, A quick introduction to stability and NIP: Part I. Basic first order logic
DESCRIPTION:I give a quick survey on stability and NIP(Non-Independent Property). We first review basic facts on the first order logic and give some historical remarks on classification theory in model theory. We review basic properties of stability and NIP. Finally\, we aim to give several characterizations of stability and NIP of a given formula in terms of counting types and definability types.
URL:https://dimag.ibs.re.kr/event/2020-08-31/
LOCATION:Room B232\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20200831T161500
DTEND;TZID=Asia/Seoul:20200831T171500
DTSTAMP:20260424T063547
CREATED:20200825T130503Z
LAST-MODIFIED:20240707T082818Z
UID:2851-1598890500-1598894100@dimag.ibs.re.kr
SUMMARY:Junguk Lee (이정욱)\, A quick introduction to stability and NIP: Part II. Stability
DESCRIPTION:I give a quick survey on stability and NIP(Non-Independent Property). We first review basic facts on the first order logic and give some historical remarks on classification theory in model theory. We review basic properties of stability and NIP. Finally\, we aim to give several characterizations of stability and NIP of a given formula in terms of counting types and definability types.
URL:https://dimag.ibs.re.kr/event/2020-08-31-part2/
LOCATION:Room B232\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
END:VCALENDAR