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A simple theorem is proved which states a sufficient condition for the sum ot two closed subspaces of a Banach space to be closed. This leads to several analogues of Sarason’s theorem which states that $H^{\infty} + C$ is a closed subalgebra of $L^{\infty}$ . In these analogues, the unit circle is replaces by other groups, and the unit disc is replaced by polydiscs or by balls in spaces of several complex variables. Sums of closed ideals in Banach algebras are also studied.

Stable Convex Sets and Extremal Operators.

A. Clausing, S. Papadopoulous (1977)

Mathematische Annalen

Starrheitssätze für Produkte normierter Vektorräume endlicher Dimension und für Produkte hyperbolischer komplexer Räume.

Konrad Peters (1974)

Mathematische Annalen

Strongly summable sequences defined over real $n$ -normed spaces.

Dutta, Hemen, Reddy, B.Surender, Cheng, Sui Sun (2010)

Applied Mathematics E-Notes [electronic only]

Subseries in Banach spaces

Benoy Kumar Lahiri, Pratulananda Das (2002)

Mathematica Slovaca

Subspaces with a common complement in a Banach space

Dimosthenis Drivaliaris, Nikos Yannakakis (2007)

Studia Mathematica

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...

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Semi-Fredholm Maps of FK Spaces.

Séries de variables aléatoires vectorielles indépendantes et propriétés géométriques des espaces de Banach

Sets with the Radon-Nikodým property in conjugate Banach space

Smoothability versus dentability

Sobre L-órdenes entre t-normas estrictas.

Solution and stability of a mixed type cubic and quartic functional equation in quasi-Banach spaces.

Solutions of $∥ f (ξ + η) ∥ = ∥ f (ξ) + f (η) ∥$ .

Some equivalent geometrical results with Ekeland's variational principle.

Some more Banach spaces which contain l¹

Some Normed Barrelled Spaces which are not Baire.

Some remarks on the triangle inequality for norms.

Spaces of type $H^{\infty} + C$

Stable Convex Sets and Extremal Operators.

Starrheitssätze für Produkte normierter Vektorräume endlicher Dimension und für Produkte hyperbolischer komplexer Räume.

Strongly summable sequences defined over real $n$ -normed spaces.

Subseries in Banach spaces

Subspaces with a common complement in a Banach space

Sufficient condition for Pareto optimization in Banach spaces

Suites concordantes d'espaces normés et leurs applications I

Sums of independent Banach space valued random variables

Currently displaying 1 – 20 of 29