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 The competition index of a nearly reducible Boolean matrix Bull. Korean Math. Soc. 2013 Vol. 50, No. 6, 2001-2011 https://doi.org/10.4134/BKMS.2013.50.6.2001Published online November 1, 2013 Han Hyuk Cho and Hwa Kyung Kim Seoul National University, Sangmyung University Abstract : Cho and Kim \cite{chokim} have introduced the concept of the competition index of a digraph. Similarly, the competition index of an $n \times n$ Boolean matrix $A$ is the smallest positive integer $q$ such that $A^{q+i}(A^T)^{q+i}$ $= A^{q+r+i}(A^T)^{q+r+i}$ for some positive integer $r$ and every nonnegative integer $i$, where $A^T$ denotes the transpose of $A$. In this paper, we study the upper bound of the competition index of a Boolean matrix. Using the concept of Boolean rank, we determine the upper bound of the competition index of a nearly reducible Boolean matrix. Keywords : competition graph, $m$-step competition graph, competition index, competition period, scrambling index MSC numbers : 05C20, 05C50 Downloads: Full-text PDF