Revisitation of Generalized and Hypergeneralized Projectors
Oskar Maria Baksalary · 2008
The notions of generalized and hypergeneralized projectors, introduced by Groβ and Trenkler [Generalized and hypergeneralized projectors, Linear Algebra Appl. 264 (1997) 463–474], attracted recently considerable attention. The list of publications devoted to them comprises now over ten positions, and the present paper briefly discusses some of the results available in the literature. Furthermore, several new characteristics of generalized and hypergeneralized projectors are established with the use of Corollary 6 in Hartwig and Spindelböck [Matrices for which A* and A † commute. Linear Multilinear Algebra 14 (1984) 241–256].