A Note on Broom Number and Maximum Edge-Cut of Graphs

Zhen-Mu Hong1, Xinmin Hou2, Jiaao Li3, Yang Yang2
1School of Finance, Anhui University of Finance and Economics, Bengbu 233030, China.
2School of Mathematical Sciences, University of Science and Technology of China, Hefei 230026, China.
3Department of Mathematics, West Virginia University, Morgantown, WV 26506, U.S.A.

Abstract

A model for cleaning a graph with brushes was first introduced by Messinger, Nowakowski, and Pralat in 2008. Later, they focused on the problem of determining the maximum number of brushes needed to clean a graph. This maximum number of brushes needed to clean a graph in the model is called the broom number of the graph. In this paper, we show that the broom number of a graph is equal to the size of a maximum edge-cut of the graph, and prove the \(\mathcal{NP}\)-completeness of the problem of determining the broom number of a graph. As an application, we determine the broom number exactly for the Cartesian product of two graphs.