Further characterizations and representations of the Minkowski inverse in Minkowski space

This paper serves to identify some new characterizations and representations of the Minkowski inverse in Minkowski space. First of all, a few representations of $\{1,3^{\mathfrak{m}}\}$-, $\{1,2,3^{\mathfrak{m}}\}$-, $\{1,4^{\mathfrak{m}}\}$- and $\{1,2,4^{\mathfrak{m}}\}$-inverses are given in order to represent the Minkowski inverse. Second, some famous characterizations of the Moore-Penrose inverse are extended to that of the Minkowski inverse. Third, using the Hartwig-Spindelböck decomposition, we present a representation of the Minkowski inverse. And, based on this result, an interesting characterization of the Minkowski inverse is showed by a rank equation. Finally, we obtain several new representations of the Minkowski inverse in a more general form, by which the Minkowski inverse of a class of block matrices is given.