Journal or Book Title
Electronic Journal of Linear Algebra
A simple digraph describes the off-diagonal zero-nonzero pattern of a family of (not necessarily symmetric) matrices. Minimum rank of a simple digraph is the minimum rank of this family of matrices; maximum nullity is defined analogously. The simple digraph zero forcing number is an upper bound for maximum nullity. Cut-vertex reduction formulas for minimum rank and zero forcing number for simple digraphs are established. The effect of deletion of a vertex on minimum rank or zero forcing number is analyzed, and simple digraphs having very low or very high zero forcing number are characterized.
Berliner, Adam; Catral, Minerva; Hogben, Leslie; Huynh, My; Lied, Kelsey; and Young, Michael, "Minimum rank, maximum nullity, and zero forcing number of simple digraphs" (2013). Mathematics Publications. 238.