English

Nonnegativity of the second largest eigenvalue of $4 \times 4$ tridiagonal stochastic matrices

Probability 2026-05-11 v1

Abstract

The spectral study of nonnegative and more specifically stochastic matrices is an important topic in matrix theory. In this paper, we prove a conjecture, formulated by Ran and Teng, which states that the second largest eigenvalue of an irreducible 4×44\times4 tridiagonal stochastic matrix is nonnegative. We establish this conjecture and extend the result to arbitrary 4×44\times4 tridiagonal stochastic matrices, including both irreducible and reducible cases.

Keywords

Cite

@article{arxiv.2605.07591,
  title  = {Nonnegativity of the second largest eigenvalue of $4 \times 4$ tridiagonal stochastic matrices},
  author = {Brando Vagenende and Brecht Verbeken and Marie-Anne Guerry},
  journal= {arXiv preprint arXiv:2605.07591},
  year   = {2026}
}