KPPY 91

Tatsuro Ito, Kim Kijeong, Elena Konstantinova, Ilkyoo Choi

KPPY 91

Jan 11, 2019. 11:00am-5:30pm at Hotel Nongshim, Pusan.

Schedule
11:00am - 11:50 Tatsuro Ito
Anhui University China
After the monumental paper of Terwilliger:

12pm - 1:25 Lunch
1:30 - 2:20 Kim Kijeong
Pusan national university
TBA
2:30 - 3:20 Elena Konstantinova
Sobolev Institute of Mathematics, Russia
Algebraic approach to hamiltonicity of Cayley graphs
3:30 - 4:20 Ilkyoo Choi
Hankuk university of foreign studies
Factor theory of graphs and largest regular subgraphs
4:30 - 5:20 TBA
TBA

Abstracts



Tatsuro Ito
After the monumental paper of Terwilliger:

I will discuss what has been done and left to be done after the monumental paper of Terwilliger: The Subconstituent Algebra of an Association scheme I, II, III.
Kim Kijeong
TBA
TBA
Elena Konstantinova
Algebraic approach to hamiltonicity of Cayley graphs
In this talk we discuss hamiltonian problem on Cayley graphs. In particular, we present an approach for constructing hamiltonian cycles in Cayley graphs over the symmetric group. This aproach is based on cyclic coverings of graphs and algebraic operations with them. This is joint work with Alexey Medvedev, Universite de Namur, Belgium.
Ilkyoo Choi
Factor theory of graphs and largest regular subgraphs
For a graph GG, let f2(G)f_2(G) denote the largest number of vertices in a 22-regular subgraph of GG. We determine the minimum of f2(G)f_2(G) over 33-regular nn-vertex simple graphs GG. To do this, we prove that every 33-regular multigraph with exactly cc cut-edges has a 22-regular subgraph that omits at most max{0,(c1)/2}\max\{0,\lfloor (c-1)/2\rfloor\} vertices. More generally, every nn-vertex multigraph with maximum degree 33 and mm edges has a 22-regular subgraph that omits at most max{0,(3n2m+c1)/2}\max\{0,\lfloor (3n-2m+c-1)/2\rfloor\} vertices. These bounds are sharp; we describe the extremal multigraphs. This is joint work with R. Kim, A. Kostochka, B. Park, and D. B. West.
TBA