Seminar
The 3rd Combinatorics Seminar, 2012

Hold Date 
20120922 12:55～20120922 17:30 


Place 
ACROS Fukuoka Seminar Room 1 


Object person 



Speaker 
Yoshihiro Mizoguchi (Kyushu University), Chihiro Suetake (Oita University), Koji Momihara (Kumamoto University), Toshiyuki Kikuta (Osaka Institute Of Technology), Masashi Shinohara (Suzuka National College of Technology) 

Program(13:00～17:25)
Yoshihiro Mizoguchi (Kyushu University)
Title：Graph partitioning and eigen polynomials of Laplacian matrices of Roachtype graphs
Chihiro Suetake (Oita University)
Title：Class regular symmetric transversal designs with semiregular automorphism groups
Koji Momihara (Kumamoto University)
Title： Inequivalent skew Hadamard difference sets and their applications
Toshiyuki Kikuta (Osaka Institute Of Technology)
Title：On a generalization of Ramanujan type congruences to the case of several variables
Masashi Shinohara (Suzuka National College of Technology)
Title：On a deformation of twodistance sets and its minimal dimension
Abstract：
(For a simple graph G of order n (except for a complete graph and a null graph), there exists a unique twodistance set with dimension less than n  1 which is corresponding to G . Let Emb(G) be a such twodistance set and m(G) be the minimal dimension. Then we have m(G) + m(G) ≥ n + 1 where G is the complement graph of G . Complete bipartite K(i, j) and complete mulitipartite graph K(i,i,i,...,i)are important examples which satisfy the equality of the above inequality. In this tale, we give a geometrical construction of Emb(G) where G = K(i_{1}, i_{2},…, i_{k}) . We also give a necessary and sufficient condition for Emb(G) is on a sphere.)