M. McGinnis

collaborators

2 papers

math.CO2017

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

Andries E. Brouwer, Sebastian M. Cioabă, Ferdinand Ihringer +1

We prove a conjecture by Van Dam and Sotirov on the smallest eigenvalue of (distance- $j$ ) Hamming graphs and a conjecture by Karloff on the smallest eigenvalue of (distance- $j$ ) Jo…

math.CO2017

Cospectral mates for the union of some classes in the Johnson association scheme

Sebastian M. Cioabă, Willem H. Haemers, Travis Johnston +1

Let $n \geq k \geq 2$ be two integers and $S$ a subset of ${0, 1, \dots, k - 1}$ . The graph $J_{S} (n, k)$ has as vertices the $k$ -subsets of the $n$ -set $[n] = {1, \dots, n}$ and two $k$ -s…