Equitable 2-partitions of Johnson graphs with the second eigenvalue
Combinatorics
2020-03-25 v1
Abstract
We study equitable 2-partitions of the Johnson graphs J(n,w) with a quotient matrix containing the eigenvalue lambda_2(w,n) = (w-2)(n-w-2)-2 in its spectrum. For any w>=4 and n>=2w, we find all admissible quotient matrices of such partitions, and characterize all these partitions for w>=4, n>2w, and for w>=7, n = 2w, up to equivalence.
Cite
@article{arxiv.2003.10956,
title = {Equitable 2-partitions of Johnson graphs with the second eigenvalue},
author = {Konstantin Vorob'ev},
journal= {arXiv preprint arXiv:2003.10956},
year = {2020}
}
Comments
16 pages