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PRODID:-//Discrete Mathematics Group - ECPv6.2.8.2//NONSGML v1.0//EN
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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
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TZOFFSETFROM:+0900
TZOFFSETTO:+0900
TZNAME:KST
DTSTART:20230101T000000
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BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20231212T163000
DTEND;TZID=Asia/Seoul:20231212T173000
DTSTAMP:20231210T165715
CREATED:20231019T075456Z
LAST-MODIFIED:20231103T230010Z
UID:7777-1702398600-1702402200@dimag.ibs.re.kr
SUMMARY:Ting-Wei Chao (趙庭偉)\, Tight Bound on Joints Problem and Partial Shadow Problem
DESCRIPTION:Given a set of lines in $\mathbb R^d$\, a joint is a point contained in d linearly independent lines. Guth and Katz showed that N lines can determine at most $O(N^{3/2})$ joints in $\mathbb R^3$ via the polynomial method. \nYu and I proved a tight bound on this problem\, which also solves a conjecture proposed by Bollobás and Eccles on the partial shadow problem. It is surprising to us that the only known proof of this purely extremal graph theoretic problem uses incidence geometry and the polynomial method.
URL:https://dimag.ibs.re.kr/event/2023-12-12/
LOCATION:Room B332\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20231219T163000
DTEND;TZID=Asia/Seoul:20231219T173000
DTSTAMP:20231210T165715
CREATED:20231015T221647Z
LAST-MODIFIED:20231207T062522Z
UID:7757-1703003400-1703007000@dimag.ibs.re.kr
SUMMARY:Shengtong Zhang (张盛桐)\, Triangle Ramsey numbers of complete graphs
DESCRIPTION:A graph is $H$-Ramsey if every two-coloring of its edges contains a monochromatic copy of $H$. Define the $F$-Ramsey number of $H$\, denoted by $r_F(H)$\, to be the minimum number of copies of $F$ in a graph which is $H$-Ramsey. This generalizes the Ramsey number and size Ramsey number of a graph. Addressing a question of Spiro\, we prove that \[r_{K_3}(K_t)=\binom{r(K_t)}3\] for all sufficiently large $t$. Our proof involves a combination of results on the chromatic number of triangle-sparse graphs.
URL:https://dimag.ibs.re.kr/event/2023-12-19/
LOCATION:Room B332\, IBS (기초과학연구원)
CATEGORIES:Discrete Math Seminar
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