Abstract:It is known that the existence of the group inverse # of a ring element is equivalent to the invertibility of 2 − + 1 − − , independently of the choice of the von Neumann inverse − of . In this paper, we relate the Drazin index of to the Drazin index of 2 − + 1 − − . We give an alternative characterization when considering matrices over an algebraically closed field. We close with some questions and remarks.
MSC:15A09, 16A14, 16A30