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 C"nxC"4 of two cycles C"n(n>=4) and C"4 is equal to 4, i.e., b(C"nxC"4)=4 for any n>=4.