96 citations · 283 across the 48 of their papers we have counts for
6 papers · 2 filters
On the Cheeger constant for distance-regular graphs
Jack Koolen, Greg Markowsky, Zhi Qiao
The Cheeger constant of a graph is the smallest possible ratio between the size of a subgraph and the size of its boundary. It is well known that this constant must be at least $\f…
Another construction of edge-regular graphs with regular cliques
Gary R. W. Greaves, J. H. Koolen
We exhibit a new construction of edge-regular graphs with regular cliques that are not strongly regular. The infinite family of graphs resulting from this construction includes an…
Addressing Johnson graphs, complete multipartite graphs, odd cycles and other graphs
Noga Alon, Sebastian M. Cioabă, Brandon D. Gilbert +2
Graham and Pollak showed that the vertices of any graph can be addressed with -tuples of three symbols, such that the distance between any two vertices may be easily determi…
A spectral characterization of the s-clique extension of the square grid graphs
Sakander Hayat, Jack H. Koolen, Muhammad Riaz
In this paper we show that for integers , , any co-edge-regular graph which is cospectral with the -clique extension of the -grid is the -clique ex…
A spectral version of the Moore problem for bipartite regular graphs
Sebastian M. Cioabă, Jack H. Koolen, Hiroshi Nozaki
Let be the maximum order of a connected bipartite -regular graph whose second largest eigenvalue is at most . In this paper, we obtain a general upper bound for $b(k…
The polytopal structure of the tight-span of a totally split-decomposable metric
K. T. Huber, J. Koolen, V. Moulton
The tight-span of a finite metric space is a polytopal complex that has appeared in several areas of mathematics. In this paper we determine the polytopal structure of the tight-sp…