8 citations · 22 across the 13 of their papers we have counts for
13 papers
An improved bound for strongly regular graphs with smallest eigenvalue
Jack Koolen, Chenhui Lv, Greg Markowsky +1
In 1979, Neumaier gave a bound on in terms of and , where is the smallest eigenvalue of a primitive strongly regular graph, unless the graph in question belongs to…
On directed strongly regular Cayley graphs over non-abelian groups with an abelian subgroup of index
Xueyi Huang, Lu Lu, Jongyook Park
In 1988, Duval introduced the concept of directed strongly regular graphs, which can be viewed as a directed graph version of strongly regular graphs. Such directed graphs have sim…
Improving the Delsarte bound
Gary R. W. Greaves, Jack H. Koolen, Jongyook Park
In this paper, we study the order of a maximal clique in an amply regular graph with a fixed smallest eigenvalue by considering a vertex that is adjacent to some (but not all) vert…
On the nonexistence of pseudo-generalized quadrangles
Ivan Guo, Jack H. Koolen, Greg Markowsky +1
In this paper we consider the question of when a strongly regular graph with parameters can exist. These parameters arise when the graph is derived f…
There does not exist a distance-regular graph with intersection array
Jack H. Koolen, Quaid Iqbal, Jongyook Park +1
In this paper we will show that there does not exist a distance-regular graph with intersection array . We first show that a local graph of doe…
Partially metric association schemes with a multiplicity three
Edwin R. van Dam, Jack H. Koolen, Jongyook Park
An association scheme is called partially metric if it has a connected relation whose distance-two relation is also a relation of the scheme. In this paper we determine the symmetr…