Brhane Gebremichel

collaborators

3 papers

math.CO2021

There does not exist a strongly regular graph with parameters $(1911, 270, 105, 27)$

Jack H. Koolen, Brhane Gebremichel

In this paper we show that there does not exist a strongly regular graph with parameters $(1911, 270, 105, 27)$ .

math.CO2021

Sesqui-regular graphs with smallest eigenvalue at least $- 3$

Qianqian Yang, Brhane Gebremichel, Masood Ur Rehman +2

Koolen et al. showed that if a graph with smallest eigenvalue at least $- 3$ has large minimal valency, then it is $2$ -integrable. In this paper, we will focus on the sesqui-regular…

math.CO2021

Two characterizations of the grid graphs

Brhane Gebremichel, Meng-Yue Cao, Jack H. Koolen

In this paper we give two characterizations of the $p \times q$ -grid graphs as co-edge-regular graphs with four distinct eigenvalues.

There does not exist a strongly regular graph with parameters (1911,270,105,27)

Sesqui-regular graphs with smallest eigenvalue at least −3

Two characterizations of the grid graphs

There does not exist a strongly regular graph with parameters $(1911, 270, 105, 27)$

Sesqui-regular graphs with smallest eigenvalue at least $- 3$