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X-WR-CALDESC:Events for Discrete Mathematics Group
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TZID:Asia/Seoul
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TZOFFSETFROM:+0900
TZOFFSETTO:+0900
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DTSTART:20210101T000000
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BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20220602T103000
DTEND;TZID=Asia/Seoul:20220602T113000
DTSTAMP:20260420T084720
CREATED:20220602T013000Z
LAST-MODIFIED:20240707T075917Z
UID:5595-1654165800-1654169400@dimag.ibs.re.kr
SUMMARY:Jeck Lim\, Sums of linear transformations
DESCRIPTION:We show that if $L_1$ and $L_2$ are linear transformations from $\mathbb{Z}^d$ to $\mathbb{Z}^d$ satisfying certain mild conditions\, then\, for any finite subset $A$ of $\mathbb{Z}^d$\, \[ |L_1 A+L_2 A|\geq (|\det(L_1)|^{1/d}+|\det(L_2)|^{1/d})^d |A|- o(|A|).\] This result corrects and confirms the two-summand case of a conjecture of Bukh and is best possible up to the lower-order term for many choices of $L_1$ and $L_2$. As an application\, we prove a lower bound for $|A  + \lambda \cdot A|$ when $A$ is a finite set of real numbers and $\lambda$ is an algebraic number.\nJoint work with David Conlon.
URL:https://dimag.ibs.re.kr/event/2022-06-02/
LOCATION:Zoom ID: 870 0312 9412 (ibsecopro) [CLOSED]
CATEGORIES:Virtual Discrete Math Colloquium
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BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20220602T161500
DTEND;TZID=Asia/Seoul:20220602T171500
DTSTAMP:20260420T084720
CREATED:20220602T071500Z
LAST-MODIFIED:20240705T172222Z
UID:5763-1654186500-1654190100@dimag.ibs.re.kr
SUMMARY:O-joung Kwon (권오정)\, Graph minor theory and beyond
DESCRIPTION:[Colloquium\, Department of Mathematical Sciences\, KAIST] \nOne of the important work in graph theory is the graph minor theory developed by Robertson and Seymour in 1980-2010. This provides a complete description of the class of graphs that do not contain a fixed graph H as a minor. Later on\, several generalizations of H-minor free graphs\, which are sparse\, have been defined and studied. Also\, similar topics on dense graph classes have been deeply studied. In this talk\, I will survey topics in graph minor theory\, and discuss related topics in structural graph theory.
URL:https://dimag.ibs.re.kr/event/2022-06-02-kwon/
LOCATION:Room 1501\, Bldg. E6-1\, KAIST
CATEGORIES:Colloquium
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