96 citations · 292 across the 62 of their papers we have counts for
6 papers · 1 filter
Fat Hoffman graphs with smallest eigenvalue at least
Akihiro Munemasa, Yoshio Sano, Tetsuji Taniguchi
In this paper, we show that all fat Hoffman graphs with smallest eigenvalue at least -1-τ, where τis the golden ratio, can be described by a finite set of fat (-1-τ)-irreducible Ho…
Upper bounds on cyclotomic numbers
Koichi Betsumiya, Mitsugu Hirasaka, Takao Komatsu +1
In this article, we give upper bounds for cyclotomic numbers of order e over a finite field with q elements, where e is a divisor of q-1. In particular, we show that under certain…
On fat Hoffman graphs with smallest eigenvalue at least -3
Hye Jin Jang, Jack Koolen, Akihiro Munemasa +1
We investigate fat Hoffman graphs with smallest eigenvalue at least -3, using their special graphs. We show that the special graph S(H) of an indecomposable fat Hoffman graph H is…
Nomura algebras of nonsymmetric Hadamard models
Takuya Ikuta, Akihiro Munemasa
We show that the Nomura algebra of the nonsymmetric Hadamard model coincides with the Bose-Mesner algebra of the directed Hadamard graph.
A complete classification of doubly even self-dual codes of length 40
Koichi Betsumiya, Masaaki Harada, Akihiro Munemasa
A complete classification of binary doubly even self-dual codes of length 40 is given. As a consequence, a classification of binary extremal self-dual codes of length 38 is also gi…
A note on super Catalan numbers
Evangelos Georgiadis, Akihiro Munemasa, Hajime Tanaka
We show that the super Catalan numbers are special values of the Krawtchouk polynomials by deriving an expression for the super Catalan numbers in terms of a signed set.