Regular nonnegative matrices
Robert J. Plemmons · Proceedings of the American Mathematical Society · 1973
Regular elements in the semigroup ${\mathcal {N}_n}$ of all $n \times n$ nonnegative matrices are characterized. The regular $\mathcal {D}$-classes in ${\mathcal {N}_n}$ are investigated and an alternate proof is given for a theorem of Flor characterizing the maximal subgroups.