Bondage number of the discrete torus Cn×C4

The bondage number b(G) of a graph G is the cardinality of a smallest set of edges whose removal from G results in a graph with a domination number greater than the domination number of G. In this paper, we show that the bondage number of the Cartesian product Cn×C4 of two cycles Cn(n⩾4) and C4 is equal to 4, i.e., b(Cn×C4)=4 for any n⩾4.