Institute of Mathematics for Industry

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The 3rd Combinatorics Seminar, 2012


Hold Date 2012-09-22 12:55~2012-09-22 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 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
Abstract:
(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.)


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