English

The first eigenvector of a distance matrix is nearly constant

Functional Analysis 2022-12-07 v2 Combinatorics

Abstract

Let x1,,xnx_1, \dots, x_n be points in a metric space and define the distance matrix DRn×nD \in \mathbb{R}^{n \times n} by Dij=d(xi,xj){D}_{ij} = d(x_i, x_j). The Perron-Frobenius Theorem implies that there is an eigenvector vRnv \in \mathbb{R}^n_{} with non-negative entries associated to the largest eigenvalue. We prove that this eigenvector is nearly constant in the sense that the inner product with the constant vector 1Rn\mathbb{1} \in \mathbb{R}^n is large v,112v212 \left\langle v, \mathbb{1} \right\rangle \geq \frac{1}{\sqrt{2}} \cdot \| v\|_{\ell^2} \cdot \|\mathbb{1} \|_{\ell^2} and that each entry satisfies viv2/4nv_i \geq \|v\|_{\ell^2}/\sqrt{4n}. Both inequalities are sharp.

Keywords

Cite

@article{arxiv.2205.15920,
  title  = {The first eigenvector of a distance matrix is nearly constant},
  author = {Stefan Steinerberger},
  journal= {arXiv preprint arXiv:2205.15920},
  year   = {2022}
}
R2 v1 2026-06-24T11:34:46.620Z