1 citations · 1 across the 4 of their papers we have counts for
7 papers
Sesqui-regular graphs with smallest eigenvalue at least
Qianqian Yang, Brhane Gebremichel, Masood Ur Rehman +2
Koolen et al. showed that if a graph with smallest eigenvalue at least has large minimal valency, then it is -integrable. In this paper, we will focus on the sesqui-regular…
Some Remarks on Systems of Equiangular Lines
Mengyue Cao, Jack H. Koolen, Jae Young Yang
In this note, we study the maximum number of a system of equiangular lines in with cosine , where is not an odd positive integer. This note i…
Sesqui-regular graphs with fixed smallest eigenvalue
Jack H. Koolen, Brhane Gebremichel, Jae Young Yang +1
Let be an integer. For strongly regular graphs with parameters and smallest eigenvalue , Neumaier gave two bounds on by using algebraic property of s…
On the order of regular graphs with fixed second largest eigenvalue
Jae Young Yang, Jack H. Koolen
Let be the maximum number of vertices of a connected -regular graph with second largest eigenvalue at most . The Alon-Boppana Theorem implies that is fini…
On graphs with smallest eigenvalue at least -3 and their lattices
Jack H. Koolen, Jae Young Yang, Qianqian Yang
In this paper, we show that a connected graph with smallest eigenvalue at least -3 and large enough minimal degree is 2-integrable. This result generalizes a 1977 result of Hoffman…
A generalization of a theorem of Hoffman
Jack H. Koolen, Qianqian Yang, Jae Young Yang
In 1977, Hoffman gave a characterization of graphs with smallest eigenvalue at least . In this paper we generalize this result to graphs with smaller smallest eigenvalue. For t…