Improved Approximation for Broadcasting in k-cycle Graphs

Broadcasting is an information dissemination primitive where a message originates at a node (called the originator) and is passed to all other nodes in the network. Broadcasting research is motivated by efficient network design and determining the broadcast times of standard network topologies. Verifying the broadcast time of a node $v$ in an arbitrary network $G$ is known to be NP-hard. Additionally, recent findings show that the broadcast time problem is also NP-complete in general cactus graphs and some highly restricted subfamilies of cactus graphs. These graph families are structurally similar to $k$-cycle graphs, in which the broadcast time problem is also believed to be NP-complete. In this paper, we present a simple $(1.5-\epsilon)$-approximation algorithm for determining the broadcast time of networks modeled using $k$-cycle graphs, where $\epsilon > 0$ depends on the structure of the graph.