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Hakata Workshop 2014 の履歴(No.10)


Hakata Workshop 2014

~ 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

  • Yoshihiro Mizoguchi (Kyushu University),
  • Hayato Waki (Kyushu University),
  • Takafumi Shibuta (Kyushu University),
  • Tetsuji Taniguchi (Matsue College of Technology),
  • Osamu Shimabukuro (Nagasaki University)
  • Makoto Tagami ( Kyushu Institute of Technology),
  • Hirotake Kurihara (Kitakyushu National College of Technology)
  • Shuya Chiba (Kumamoto University)

Supported by

Date

Saturday, February 8, 2014

Location

Program

SpeakerTitle
9:15--9:20Opening (Tetsuji Taniguchi)
9:20--10:00Shoichi Tsuchiya (Tokyo University of Science)On Halin graphs and generalized Halin graphs
10:10--10:50Shuya Chiba (Kumamoto University)On the number of components of -factors in claw-free graphs
11:00--11:40Masashi Shinohara (Shiga University)On complementary Ramsey numbers
13:10--15:20Poster Session (Software in Mathematics Demonstration Track)
15:40--16:20Michio Seto (Shimane University)Graph homomorphisms and de Branges-Rovnyak theory
16:20--17:00TBATBA
17:10--17:50Shun'ichi Yokoyama (Kyushu University)Computing resultant matrix of general multivariate polynomials and its determinant using Magma
17:50--18:00Closing (Yoshihiro Mizoguchi)

List of Poster session speakers

Software in Mathematics Demonstration Track

  1. TBA

Abstract

Shoichi Tsuchiya

  • Title: On Halin graphs and generalized Halin graphs
  • Abstract: A Halin graph, defined by Halin, is a plane graph such that is a spanning tree of with no vertices of degree where and is a cycle whose vertex set is the set of leaves of . On the other hand, generalized Halin graph is a graph such that is a spanning tree of with no vertices of degree where and is a cycle whose vertex set is the set of leaves of . Note that some generalized Halin graphs may not be plane graphs, (for example, Petersen graph is a generalized Halin graph which is not planar). In this talk, we introduce some known results on Halin graphs and generalized Halin graphs. After that, we investigate difference between Halin graphs and generalized Halin graphs.

Shuya Chiba

  • Title: On the number of components of -factors in claw-free graphs
  • Abstract: We consider only finite graphs without loops. A graph is said to be claw-free if has no induced subgraph isomorphic to (here denotes the complete bipartite graph with partite sets of cardinalities and , respectively). A -factor of a graph is a spanning subgraph of in which every component is a cycle. It is a well-known conjecture that every -connected claw-free graph is Hamiltonian due to Matthews and Sumner [Hamiltonian results in -free graphs, J. Graph Theory 8 (1984) 139--146]. Since a Hamilton cycle is a -factor with one component, there are many results on the upper bounds of the number of components in -factors of claw-free graphs. In this talk, we will present some recent results on the relationship between the number of components of a -factor and the minimum degree of a graph.

Masashi Shinohara

  • Title: On complementary Ramsey numbers
  • Abstract: In this talk, we propose a new generalization of Ramsey numbers which seems to be untreated in the literature.Instead of requiring the existence of a monochromatic clique, we consider the existence of a clique which avoids one of the colors in an edge coloring.These numbers are called complementary Ramsey numbers, and we derive their basic properties.We also establish their connections to graph factorizations. This is a joint work with Akihiro Munemasa.

Michio Seto

  • Title: Graph homomorphisms and de Branges-Rovnyak theory
  • Abstract: In 1960's, de Branges and Rovnyak developed a theory dealing with Hilbert space embedding . In this talk, comparing with theory of univalent functions, a de Branges-Rovnyak framework for study of graph homomorphisms will be suggested. This is joint work with S. Suda and T. Taniguchi.

Shun'ichi Yokoyama

  • Title: Computing resultant matrix of general multivariate polynomials and its determinant using Magma
  • Abstract: We produce an efficient program package to compute the resultant matrix and its determinant for a given pair of multivariate polynomials on Magma. This package works much more faster than the Magma's built-in function "Resultant" for multivariate polynomials. We also explain some applications of this package, and especially, try some benchmark problem for computing general formula of the discriminant. This work is in cooperation with Kinji Kimura (Kyoto University).