a Department of Pure Mathematics, University of Waterloo, Waterloo Ontario,, N2L 3G1, Canada
Abstract:
We investigate the structure of the multiplicative semigroup generated by the set of matrices that are unitarily equivalent to a given singular matrix A. In particular, we give necessary and sufficient conditions, in terms of the singular values of A, for such a semigroup to consist of all matrices of rank not exceeding the rank of A.