96 citations · 283 across the 48 of their papers we have counts for
4 papers · 2 filters
Max-cut and extendability of matchings in distance-regular graphs
Sebastian M. Cioabă, Jack H. Koolen, Weiqiang Li
Let be a distance-regular graph of order and size . In this paper, we show that the max-cut in is at most , where is the odd girth of . This result…
Graphs with three eigenvalues and second largest eigenvalue at most 1
Xi-Ming Cheng, Gary R. W. Greaves, Jack H. Koolen
We classify the connected graphs with precisely three distinct eigenvalues and second largest eigenvalue at most 1.
2-walk-regular dihedrants from group-divisible designs
Zhi Qiao, Shao Fei Du, Jack H. Koolen
In this note, we construct bipartite 2-walk-regular graphs with exactly 6 distinct eigenvalues as incidence graphs of group-divisible designs with the dual property. For many of th…
Maximizing the order of a regular graph of given valency and second eigenvalue
Sebastian M. Cioabă, Jack H. Koolen, Hiroshi Nozaki +1
From Alon and Boppana, and Serre, we know that for any given integer and real number , there are finitely many -regular graphs whose second largest eige…