ELA, Volume 7, pp. 53-58, July 2000, abstract.
A class of inverse M-matrices
Reinhard Nabben
Nonnegative matrices whose inverses are M-matrices are
called inverse M-matrices. It is still an open problem to
characterize all inverse M-matrices.
In this note a new class of inverse M-matrices is established.
This class of nonsymmetric matrices generalizes the class of
strictly ultrametric matrices.