K. Nomura

activity

20052026

most citedTowards a classification of the tridiagonal pairs

10 citations · 74 across the 38 of their papers we have counts for

collaborators

38 papers

math.CO2026

Variations on a circular Hessenberg pair

Kazumasa Nomura, Paul Terwilliger

A square matrix is called Hessenberg whenever each entry below the subdiagonal is zero and each entry on the subdiagonal is nonzero. A Hessenberg pair is an ordered pair of diagona…

math.CO2026

Circular Hessenberg pairs and the tridiagonal relations

Kazumasa Nomura, Paul Terwilliger

A square matrix is said to be Hessenberg whenever each entry below the subdiagonal is zero, and each entry on the subdiagonal is nonzero. A Hessenberg matrix is called circular whe…

math.CO2025

Spin Leonard pairs and the zero diagonal space

Kazumasa Nomura, Paul Terwilliger

We consider a Leonard pair $A, A^{*}$ of linear maps on a vector space $V$ that has finite positive dimension. This Leonard pair $A, A^{*}$ is said to have spin whenever there exist inv…

math.RA2024

The nucleus of the Johnson graph $J (N, D)$

Kazumasa Nomura, Paul Terwilliger

In this paper, we describe the nucleus of the Johnson graph $Γ = J (N, D)$ with $N > 2 D$ . Let $X$ denote the vertex set of $Γ$ . Let $A \in Mat_{X} (C)$ denote the adjace…

math.CO2024

The Norton-balanced condition for $Q$ -polynomial distance-regular graphs

Kazumasa Nomura, Paul Terwilliger

Let $Γ$ denote a $Q$ -polynomial distance-regular graph, with vertex set $X$ and diameter $D \geq 3$ . The standard module $V$ has a basis ${x^∣ x \in X}$ , whe…

math.RA2024

Formal self-duality and numerical self-duality for symmetric association schemes

Kazumasa Nomura, Paul Terwilliger

Let $X = (X, {R_{i}}_{i = 0}^{d})$ denote a symmetric association scheme. Fix an ordering ${E_{i}}_{i = 0}^{d}$ of the primitive idempotents of $X$ , and let $P$ (resp.…

Variations on a circular Hessenberg pair

Circular Hessenberg pairs and the tridiagonal relations

Spin Leonard pairs and the zero diagonal space

The nucleus of the Johnson graph J(N,D)

The Norton-balanced condition for Q-polynomial distance-regular graphs

Formal self-duality and numerical self-duality for symmetric association schemes

The nucleus of the Johnson graph $J (N, D)$

The Norton-balanced condition for $Q$ -polynomial distance-regular graphs