On products of EP matrices

The star partial order and the eigenprojection at 0 on EP matrices

“…Hartwig, Katz and Koliha studied when the product of two EP matrices is EP [16,20]. What can we say about the relationship between the product of two EP matrices and the partial star order?…”

On EP elements, normal elements and partial isometries in rings with involution

“…Introduction. EP matrices and normal matrices, as well as EP linear operators and normal linear operators on Banach or Hilbert spaces have been investigated by many authors (see, for example, [1,2,3,4,5,7,8,9,10,11,13,15,17,18,20]). D. Mosić et al in [21,24] use the setting of rings with involution to investigate EP elements and normal elements, giving new characterizations to them and providing simpler and more transparent proofs to already existing ones.…”

New results for EP matrices in indefinite inner product spaces

“…Obviously, this is equivalent to (AJBJ) † = (BJ) † (AJ) † . Now, by Corollary 2 in [6], we get that AJBJ is an EP matrix, which is by Lemma 2.1 equivalent to A • B being a J-EP matrix.…”