Posts Tagged ‘MitsuguHirasaka’

2014 KAIST CMC Discrete Math Workshop

Sunday, November 23rd, 2014
December 10–12, 2014
자연과학동(E6-1), KAIST

Preregistration in deadline: Dec. 5 (Friday)

Program (Dec.10 Wed-Room 1409)
  • 1:30-2:00 Registration
  • 2:00-2:30 Young Soo Kwon (권영수), Yeungnam University: A variation of list coloring and its properties
  • 2:40-3:10 Mitsugu Hirasaka, Pusan National University: Small topics on association schemes
  • 3:10-3:40 Coffee Break
  • 3:40-4:10 Younjin Kim (김연진),  KAIST: On Extremal Combinatorial Problems of Noga Alon
  • 4:20-4:50 Jang Soo Kim (김장수),  Sungkyunkwan University: A new q-Selberg integral, Schur functions, and Young books
  • 5:00-6:00 Discussion
  • 6:00- Dinner
Program (Dec.11 Thurs-Room 1501 & 3435)
Program (Dec.12 Fri-Room 1501)

Mitsugu Hirasaka, Zeta functions of adjacecny algebras

Friday, March 15th, 2013
Zeta functions of adjacecny algebras
Mitsugu Hirasaka
Department of Mathematics,Pusan National University
2013/03/29 Fri 4PM-5PM
For a module L the formal Dirichlet series ζL(s) = ∑n ≥ 1ann-s is defined whenever the number an of submodules of L with index n is finite for each positive integer n. For a ring R and a finite association scheme (X,S) we denote the adjacency algebra of (X,S) over R by RS. In this talk we aim to compute ζZS(s) where ZS is regarded as a ZS-module under the assumption that |X| is prime or |S|=2.

Mitsugu Hirasaka, Finding n such that every transitive permutation group of degree n is multiplicity-free

Friday, April 10th, 2009
Finding n such that every transitive permutation group of degree n is multiplicity-free
Mitsugu Hirasaka
Department of Mathematics, Pusan National University, Pusan, Korea
2009/5/1 Friday 4PM-5PM
This is a joint work with Cai-Heng Li. Let \mathcal{MF} denote the set of positive integers n such that each transitive action of degree n is multiplicity-free, and \mathcal{PQ} denote the set of n\in \mathbb{N} such that n=pq for some primes p, q with p<q[/latex] and [latex](p,q-1)=1[/latex] where (m,l) is the greatest common divisor of m and n. Our main result shows that [latex]\mathcal{PQ}\backslash \mathcal{MF}[/latex] is the union of <center>[latex]\{pq\in \mathcal{PQ}\mid (p,q-2)=p, q\mbox{ is a Fermat prime}\} and
\{pq\in \mathcal{PQ}\mid q=2p-1\}
where its proof owes much to classification of finite simple groups.