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Cyclotomic eigenvalue question for Distance-regular graph

I have read this paper. So, I am just thinking about if the following guess is true: GUESS: Any Distance-regular graph (DRG) has cyclotomic character value property (which means the eigenvalues of a ...
user1992's user avatar
  • 109
1 vote
0 answers
188 views

Vandermonde shift

I'm looking for any known results on a shift operator commutated by a Vandermonde matrix. That is, let $$T=\begin{bmatrix}0 & 1 & 0 & 0 & \cdots \\ 0 & 0 & 1 & 0 & \...
Linas's user avatar
  • 384
9 votes
1 answer
380 views

Is an integral sum of periodic vectors always a sum of integral periodic vectors?

Update: I have found reference to this problem. It is known as "the Rédei-de Bruijn-Schönberg theorem", which is proved in the following papers: N. G. de Bruijn: On the factorization of cyclic ...
WhatsUp's user avatar
  • 3,432
10 votes
1 answer
466 views

Is there a pattern for the irreducible factors and degrees of a characteristic polynomial?

Let $Log(n) = \sum_{i=1}^r \alpha_i \cdot e_i$, where $n = \prod_{i=1}^r p_i^{\alpha_i}$ and $p_i$ is the $i$-th prime, $\alpha_i \ge 0$, $e_i$ is the $i$-th standard basis vector. For example $6 = 2\...
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2 votes
0 answers
218 views

Cyclotomic ring of integers proof via matrix theory

Not sure of a better title (and I'm open to suggestions). But when following Laffey's notes on Integer Matrices, found here (and in particular, starting on page 13), I came across an alternative proof ...
HumbabaOReilly's user avatar