Semi-Fredholm Operators and Sequence Conditions.
Some stronger and equivalent metrics are defined on , the set of all bounded normal operators on a Hilbert space and then some topological properties of are investigated.
In this note, we investigate non-locally-convex topological vector spaces for which the closed graph theorem holds. In doing so, we introduce new classes of topological vector spaces. Our study includes a direct extension of Pták duality to the non-locally-convex situation.
The paper defines and studies the Drazin inverse for a closed linear operator in a Banach space in the case that belongs to a spectral set of the spectrum of . Results are applied to extend a result of Krein on a nonhomogeneous second order differential equation in a Banach space.
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 of subspaces of a Banach space with a common complement coincide with those pairs which are isomorphic to a pair of graphs of bounded linear operators between two other Banach spaces. (2) The pairs of subspaces of a Banach space X with a common complement coincide with those pairs for which there exists an involution...