English

The smallest eigenvalues of Hamming graphs, Johnson graphs and other distance-regular graphs with classical parameters

Combinatorics 2018-04-23 v2 Discrete Mathematics

Abstract

We prove a conjecture by Van Dam and Sotirov on the smallest eigenvalue of (distance-jj) Hamming graphs and a conjecture by Karloff on the smallest eigenvalue of (distance-jj) Johnson graphs. More generally, we study the smallest eigenvalue and the second largest eigenvalue in absolute value of the graphs of the relations of classical PP- and QQ-polynomial association schemes.

Keywords

Cite

@article{arxiv.1709.09011,
  title  = {The smallest eigenvalues of Hamming graphs, Johnson graphs and other distance-regular graphs with classical parameters},
  author = {Andries E. Brouwer and Sebastian M. Cioabă and Ferdinand Ihringer and Matt McGinnis},
  journal= {arXiv preprint arXiv:1709.09011},
  year   = {2018}
}

Comments

30 pages, accepted by JCTB

R2 v1 2026-06-22T21:55:16.662Z