21 citations · 30 across the 10 of their papers we have counts for
8 papers · 1 filter
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…
Recent progress on graphs with fixed smallest eigenvalue
Jack H. Koolen, Meng-Yue Cao, Qianqian Yang
We give a survey on graphs with fixed smallest eigenvalue, especially on graphs with large minimal valency and also on graphs with good structures. Our survey mainly consists of th…
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 integrability of strongly regular graphs
Jack H. Koolen, Masood Ur Rehman, Qianqian Yang
Koolen et al. showed that if a connected graph with smallest eigenvalue at least has large minimal valency, then it is -integrable. In this paper, we will prove that a lowe…
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…
The integrally representable trees of norm 3
Jack H. Koolen, Masood Ur Rehman, Qianqian Yang
In this paper, we determine the integrally representable trees of norm 3.
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…
An application of Hoffman graphs for spectral characterizations of graphs
Qianqian Yang, Aida Abiad, Jack H. Koolen
In this paper, we present the first application of Hoffman graphs for spectral characterizations of graphs. In particular, we show that the -clique extension of the $(t+1)\times…