2 papers
math.CO2026
On perfect matchings, edge-colourings and eigenvalues of cubic graphs
Willem H. Haemers
We discuss the question whether the existence of perfect matchings in a cubic graph can be seen from the spectrum of its adjacency matrix. For regular graphs in general and for thr…
math.CO2025
Thin divisible designs graphs: an interplay between fixed-point free involutions of -graphs and symmetric weighing matrices
Sergey Goryainov, Willem H. Haemers, Elena V. Konstantinova +1
In this paper, we illustrate important aspects of the interplay between weighing matrices, -graphs with fixed-point free involutions, and signed graphs with an orthogonal…