Domination in 4-regular Kn\"odel graphs

Abstract

A subset $D$ of vertices of a graph $G$ is a dominating set if for each $u\in V(G)\setminus D$, $u$ is adjacent to some vertex $v\in D$. The domination number, $\gamma(G)$ of $G$, is the minimum cardinality of a dominating set of $G$. For an even integer $n\ge2$ and $1\le\Delta\le\lfloor\log_2n\rfloor$, a Kn\"odel graph $W_{\Delta,n}$ is a $Delta$-regular bipartite graph of even order $n$, with vertices$(i,j)$, for $i=1,2$ and $0\le j\le n/2-1$, where for every $j$, $0\le j\le n/2-1$, there is an edge between $(1,j)$ and $(2,j+2^k-1 \text{(mod(n/2)})$, for $k=0,1,\cdots,\Delta-1$. In this paper, we determine the domination number in $4$-regular Kn\"odel graphs $W_{4,n}$.