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PRODID:-//Discrete Mathematics Group - ECPv6.16.2//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
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BEGIN:VTIMEZONE
TZID:Asia/Seoul
BEGIN:STANDARD
TZOFFSETFROM:+0900
TZOFFSETTO:+0900
TZNAME:KST
DTSTART:20210101T000000
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BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20221004T163000
DTEND;TZID=Asia/Seoul:20221004T173000
DTSTAMP:20260525T100204
CREATED:20220825T224353Z
LAST-MODIFIED:20240707T074613Z
UID:6077-1664901000-1664904600@dimag.ibs.re.kr
SUMMARY:Zixiang Xu (徐子翔)\, On the degenerate Turán problems
DESCRIPTION:For a graph $F$\, the Turán number is the maximum number of edges in an $n$-vertex simple graph not containing $F$. The celebrated Erdős-Stone-Simonovits Theorem gives that \[ \text{ex}(n\,F)=\bigg(1-\frac{1}{\chi(F)-1}+o(1)\bigg)\binom{n}{2}\,\] where $\chi(F)$ is the chromatic number of $H$. This theorem asymptotically solves the problem when $\chi(F)\geqslant 3$. In case of bipartite graphs $F$\, not even the order of magnitude is known in general. In this talk\, I will introduce some recent progress on Turán numbers of bipartite graphs and related generalizations and discuss several methods developed in recent years. Finally\, I will introduce some interesting open problems on this topic.
URL:https://dimag.ibs.re.kr/event/2022-10-04/
LOCATION:Room B332\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
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BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20221011T163000
DTEND;TZID=Asia/Seoul:20221011T173000
DTSTAMP:20260525T100204
CREATED:20220824T132239Z
LAST-MODIFIED:20240707T074556Z
UID:6067-1665505800-1665509400@dimag.ibs.re.kr
SUMMARY:Nika Salia\, Exact results for generalized extremal problems forbidding an even cycle
DESCRIPTION:We determine the maximum number of copies of $K_{s\,s}$ in a $C_{2s+2}$-free $n$-vertex graph for all integers $s \ge 2$ and sufficiently large $n$. Moreover\, for $s\in\{2\,3\}$ and any integer $n$ we obtain the maximum number of cycles of length $2s$ in an $n$-vertex $C_{2s+2}$-free bipartite graph. \nThis is joint work with Ervin Győri (Renyi Institute)\, Zhen He (Tsinghua University)\, Zequn Lv (Tsinghua University)\, Casey Tompkins (Renyi Institute)\, Kitti Varga (Technical University of Budapest BME)\, and Xiutao Zhu (Nanjing University).
URL:https://dimag.ibs.re.kr/event/2022-10-11/
LOCATION:Room B332\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20221018T163000
DTEND;TZID=Asia/Seoul:20221018T173000
DTSTAMP:20260525T100204
CREATED:20220824T133830Z
LAST-MODIFIED:20240705T171142Z
UID:6071-1666110600-1666114200@dimag.ibs.re.kr
SUMMARY:Florent Koechlin\, Uniform random expressions lack expressivity
DESCRIPTION:In computer science\, random expressions are commonly used to analyze algorithms\, either to study their average complexity\, or to generate benchmarks to test them experimentally. In general\, these approaches only consider the expressions as purely syntactic trees\, and completely ignore their semantics — i.e. the mathematical object represented by the expression. \nHowever\, two different expressions can be equivalent (for example “0*(x+y)” and “0” represent the same expression\, the null expression). Can these redundancies question the relevance of the analyses and tests that do not take into account the semantics of the expressions? \nI will present how the uniform distribution over syntactic expression becomes completely degenerate when we start taking into account their semantics\, in a very simple but common case where there is an absorbing element. If time permits it\, I will briefly explain why the BST distribution offers more hope. \nThis is a joint work with Cyril Nicaud and Pablo Rotondo.
URL:https://dimag.ibs.re.kr/event/2022-10-18/
LOCATION:Room B332\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
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