Bounds for the inverses of $PM$- and $PH$-matrices

The paper presents new bounds for the inverses of the so-called $PM$- and $PH$-matrices. Also bounds for the spectral radii of the inverses to $PM$- and $PH$-matrices are obtained, and the monotonicity of these bounds with respect to the underlying partition of the index set is established. Finally, the so-called quasi-$PM$- and quasi-$PH$-matrices are introduced, and bounds for the inverses of such matrices are suggested. Bibl. – 10 titles.