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  • Cory Palmer, A survey of Turán-type subgraph counting problems

    Room B232 IBS (기초과학연구원)

    Let $F$ and $H$ be graphs. The subgraph counting function $\operatorname{ex}(n,H,F)$ is defined as the maximum possible number of subgraphs $H$ in an $n$-vertex $F$-free graph. This function is a direct generalization of the Turán function as $\operatorname{ex}(n,F)=\operatorname{ex}(n,K_2,F)$. The systematic study of $\operatorname{ex}(n,H,F)$ was initiated by Alon and Shikhelman in 2016 who generalized several classical …

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  • Casey Tompkins, Extremal problems for Berge hypergraphs

    Room B232 IBS (기초과학연구원)

    Given a graph $G$, there are several natural hypergraph families one can define. Among the least restrictive is the family $BG$ of so-called Berge copies of the graph $G$. In this talk, we discuss Turán problems for families $BG$ in $r$-uniform hypergraphs for various graphs $G$. In particular, we are interested in general results in …

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  • Alexandr V. Kostochka, Reconstructing graphs from smaller subgraphs

    Room B232 IBS (기초과학연구원)

    A graph or graph property is $\ell$-reconstructible if it is determined by the multiset of all subgraphs obtained by deleting $\ell$ vertices. Apart from the famous Graph Reconstruction Conjecture, Kelly conjectured in 1957 that for each $\ell\in\mathbb N$, there is an integer $n=n(\ell)$ such that every graph with at least $n$ vertices is $\ell$-reconstructible. We show that for …

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  • Zi-Xia Song (宋梓霞), Ramsey numbers of cycles under Gallai colorings

    Room B232 IBS (기초과학연구원)

    For a graph $H$ and an integer $k\ge1$, the $k$-color Ramsey number $R_k(H)$ is the least integer $N$ such that every $k$-coloring of the edges of the complete graph $K_N$ contains a monochromatic copy of $H$. Let $C_m$ denote the cycle on $m\ge4 $ vertices. For odd cycles, Bondy and Erd\H{o}s in 1973 conjectured that …

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  • Joonkyung Lee (이준경), On some properties of graph norms

    Room B232 IBS (기초과학연구원)

    For a graph $H$, its homomorphism density in graphs naturally extends to the space of two-variable symmetric functions $W$ in $L^p$, $p\geq e(H)$, denoted by $t_H(W)$. One may then define corresponding functionals $\|W\|_{H}:=|t_H(W)|^{1/e(H)}$ and $\|W\|_{r(H)}:=t_H(|W|)^{1/e(H)}$ and say that $H$ is (semi-)norming if $\|.\|_{H}$ is a (semi-)norm and that $H$ is weakly norming if $\|.\|_{r(H)}$ is …

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  • Extremal and Structural Graph Theory (2019 KMS Annual Meeting)

    Room 426, Hong-Mun Hall, Hongik University, Seoul

    Focus Session @ 2019 KMS Annual MeetingA focus session "Extremal and Structural Graph Theory" at the 2019 KMS Annual Meeting is organized by Sang-il Oum. URL: http://www.kms.or.kr/meetings/fall2019/SpeakersIlkyoo Choi (최일규), Hankuk University of Foreign StudiesKevin Hendrey, IBS Discrete Mathematics GroupPascal Gollin, IBS Discrete Mathematics GroupJaehoon Kim (김재훈), KAISTRingi Kim (김린기), KAISTSeog-Jin Kim (김석진), Konkuk UniversityO-joung Kwon (권오정), Incheon …

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  • Pascal Gollin, A Cantor-Bernstein-type theorem for spanning trees in infinite graphs

    Room B232 IBS (기초과학연구원)

    Given a cardinal $\lambda$, a $\lambda$-packing of a graph $G$ is a family of $\lambda$ many edge-disjoint spanning trees of $G$, and a $\lambda$-covering of $G$ is a family of spanning trees covering $E(G)$.We show that if a graph admits a $\lambda$-packing and a $\lambda$-covering  then the graph also admits a decomposition into $\lambda$ many spanning …

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  • The 2nd East Asia Workshop on Extremal and Structural Graph Theory

    UTOP UBLESS Hotel, Jeju, Korea (유탑유블레스호텔제주)

    The 2nd East Asia Workshop on Extremal and Structural Graph Theory is a workshop to bring active researchers in the field of extremal and structural graph theory, especially in the East Asia such as China, Japan, and Korea.DateOct 31, 2019 (Arrival Day) - Nov 4, 2019 (Departure Day)Venue and Date1st floor  Diamond HallUTOP UBLESS Hotel, …

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  • Sun Kim (김선), Two identities in Ramanujan’s Lost Notebook with Bessel function series

    Room 1401, Bldg. E6-1, KAIST

    On page 335 in his lost notebook, Ramanujan recorded without proofs two identities involving finite trigonometric sums and doubly infinite series of Bessel functions. We proved each of these identities under three different interpretations for the double series, and showed that they are intimately connected with the classical circle and divisor problems in number theory. …

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