collaborators

5 papers

math.CO2025

Combinatorial characterzations of -designs in the nonbinary Johnson scheme

Hiroshi Nozaki, Yuta Watanabe

We study -designs in the nonbinary Johnson scheme. This scheme generalizes both the Johnson and Hamming schemes and admits a bivariate -polynomial structure. Zhu (2021) provi…

math.CO2025

The non-existence of some Moore polygons and spectral Moore bounds

Sebastian M. Cioabă, Vishal Gupta, Hiroshi Nozaki +1

In this paper, we study the maximum order of a connected -regular graph whose second largest eigenvalue is at most . From Alon-Boppana and Serre, we know that $v(k…

math.CO2025

On the existence and non-existence of spherical -stiff configurations

Eiichi Bannai, Hirotake Kurihara, Hiroshi Nozaki

This paper investigates the existence of -stiff configurations in the unit sphere , which are spherical -designs that lie on parallel hyperplanes. We establ…

math.CO2025

Spherical designs for finite quaternionic unit groups and their applications to modular forms

Masatake Hirao, Hiroshi Nozaki, Koji Tasaka

For a finite subset of the -dimensional unit sphere, the harmonic strength of is the set of such that for all harmonic…

math.CO2025

Algebro-combinatorial generalizations of the Victoir method for constructing weighted designs

Hiroshi Nozaki, Masanori Sawa

A weighted -design in is a finite weighted set that exactly integrates all polynomials of degree at most with respect to a given probability measure. A fundam…