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The 3rd Combinatorics Seminar, 2012

Hold Date
2012-09-22 12:55〜2012-09-22 17:30
ACROS Fukuoka Seminar Room 1
Object person
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)


Yoshihiro Mizoguchi (Kyushu University)
Title:Graph partitioning and eigen polynomials of Laplacian matrices of Roach-type 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 two-distance sets and its minimal dimension
(For a simple graph G of order n (except for a complete graph and a null graph), there exists a unique two-distance set with dimension less than n - 1 which is corresponding to G . Let Emb(G) be a such two-distance 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(i1, i2,…, ik) . We also give a necessary and sufficient condition for Emb(G) is on a sphere.)