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Hakata Workshop;Summer Meeting 2019 の履歴(No.1)


Hakata Workshop; Summer Meeting 2019

~Discrete Mathematics and its Applications~

 

Our purpose of this meeting is giving an opportunity to make a speech and to communicate with researchers who study various fields not only Combinatorics.

Further information is available from the organizers below.

Organizers

Supported by

  • Graduate School of Mathematics, Kyushu University
  • JSPS KAKENHI(Grant-in-Aid for Scientific Research (C)) Grant Number 17K05346
  • JSPS KAKENHI(Grant-in-Aid for Scientific Research (C)) Grant Number 16K05263
  • JSPS KAKENHI(Grant-in-Aid for Scientific Research (C)) Grant Number 19K03425

Date

June 15, 2019

Location

Seminar Room P (4F) in Reference Eki Higashi Building. 1-16-14 Hakata-Eki-Higashi, Hakata-Ku, Fukuoka City, 812-0013 (see http://www.re-rental.com/ , Google maps )

Program

SpeakerTitle
15:07--15:10Opening (Tetsuji Taniguchi)
15:10-15:50Tetsuji Taniguchi (Hiroshima Institute of Technology)A generalization of Hoffman graph
16:00-16:40Yagita Tsuyoshi (Kyushu Institute of Technology) On $k$-path Vertex Cover problem and its maximization
16:50-17:30Aokage Kazuya (National Institute of Technology, Ariake College)Tensor products for the group related to the symmetric groups
17:30--17:35Closing

Abstract

Tetsuji Taniguchi

  • Title: A generalization of Hoffman graph
  • Abstract: ホフマングラフはWoo氏,Neumaier氏らによって,最小固有値が$-1-\sqrt {2}$以上 ($-2$未満)であるグラフの研究の中で導入された。 与えられた値$\lambda (\le-2)$に対し,(従来の)ホフマングラフ$\ge\lambda$の和で表せないグラフが存在する。そこで,我々はfat頂点に重みを,辺に符号``$\pm$"を与えることでホフマングラフの一般化を与えた。これにより,すべてのグラフ$\ge\lambda$が(新しい)ホフマングラフの和で表すことが出来るようになった。 本講演ではこのことについて幾つかの結果を交えて話したい。

Yagita Tsuyoshi

  • Title: On $k$-path Vertex Cover problem and its maximization
  • Abstract: Vertex Cover Problem (\texttt{VCP}) is one of the most popular graph optimization problems. Given a graph $G=(V,E)$ and integer $s$, \texttt{VCP} asks to find a vertex subset $S$ of size at most $s$ such that $G[V\setminus S]$ induces no edges. Recently, $k$-path Vertex Cover Problem (\texttt{$P_k$VCP}) was proposed and attracted much attention. \texttt{$P_k$VCP} aims to monitor all paths of $k$ vertices, thus is a natural generalization of the original vertex cover. In this talk, we talk about its maximization version and show the obtained results.

Aokage Kazuya

  • Title: Tensor products for the group related to the symmetric groups
  • Abstract: The covering groups of the finite group G is introduced by Schur who investigated the projective representations of G. We consider the tensor products of the covering groups for the symmetric group. In this case, the tensor products have (i) linear and linear, (ii) linear and spin, and (iii) spin and spin. When n is odd, Stembridge(1989) derived the results of (ii) and (iii) for the basic spin. In this talk, we present the results when n is even.