Digraphs and inclusion intervals of Brualdi-type for singular values (Q1862822)

The authors study some properties of \(n\)-by-\(n\) complex matrices \(A\) and their associated digraph \(D(A)\). A matrix \(A\) has property \(B\) if and only if all singular values are contained in some union. A digraph \(D\) is a forcible \(B\)-digraph if each matrix realization of \(D\) has property \(B\). The authors give a sufficient condition for a matrix to have property \(B\), and they characterize the forcible \(B\)-digraphs.