10 citations · 23 across the 7 of their papers we have counts for
4 papers · 2 filters
Factorizations of EP operators
Dimosthenis Drivaliaris, Sotirios Karanasios, Dimitrios Pappas
In this paper we characterize EP operators through the existence of different types of factorizations. Our results extend to EP operators existing characterizations for EP matrices…
Hilbert space structure and positive operators
D. Drivaliaris, N. Yannakakis
Let X be a real Banach space. We prove that the existence of an injective, positive, symmetric and not strictly singular operator from X into its dual implies that either X admits…
Generalizations of the Lax-Milgram theorem
D. Drivaliaris, N. Yannakakis
We prove a linear and a nonlinear generalization of the Lax-Milgram theorem. In particular we give sufficient conditions for a real-valued function defined on the product of a refl…
Subspaces with a common complement in a Banach space
D. Drivaliaris, N. Yannakakis
We study the problem of the existence of a common algebraic complement for a pair of closed subspaces of a Banach space. We prove the following two characterizations: (1) The pairs…