In this paper we give some necessary and sufficient conditions for which each Banach lattice  is    space and we study some properties of b-weakly compact operators from a Banach lattice  into a Banach space . We show that every weakly compact operator from a Banach lattice  into a Banach space  is b-weakly compact and give a counterexample which shows that the inverse is not true but we prove ...

Motivated by an Arens regularity problem, we introduce the concepts of matrix Banach space and matrix Banach algebra. The notion of matrix normed space in the sense of Ruan is a special case of our matrix normed system. A matrix Banach algebra is a matrix Banach space with a completely contractive multiplication. We study the structure of matrix Banach spaces and matrix Banach algebras. Then we...

We work in the set theory without the axiom of choice: ZF. Though the Hahn-Banach theorem cannot be proved in ZF, we prove that every Gâteauxdifferentiable uniformly convex Banach space E satisfies the following continuous Hahn-Banach property: if p is a continuous sublinear functional on E, if F is a subspace of E, and if f : F → R is a linear functional such that f ≤ p|F , then there exists a...

We show that for every separable Banach space X, either SPw(X) (the set of all spreading models of X generated by weakly-null sequences in X, modulo equivalence) is countable, or SPw(X) contains an antichain of the size of the continuum. This answers a question of S. J. Dilworth, E. Odell and B. Sari.

In this paper, some fixed point principle is applied to prove the existence of solutions for delay second order differential inclusions with three-point boundary conditions in the context of a separable Banach space. A topological property of the solutions set is also established.

We provide a new proof of James’ sup theorem for (non necessarily separable) Banach spaces. One of the ingredients is the following generalization of a theorem of Hagler and Johnson ([5]) : “If a normed space E does not contain any asymptotically isometric copy of l(N), then every bounded sequence of E′ has a normalized block sequence pointwise converging to 0”.

Total subspaces in dual Banach spaces which are not norming over any infinite dimensional subspace Abstract. The main result: the dual of separable Banach space X contains a total subspace which is not norming over any infinite dimensional subspace of X if and only if X has a nonquasireflexive quotient space with the strictly singular quotient mapping. Let X be a Banach space and X * be its dua...

We construct a complete metric space M of cardinality continuum such that every non-singleton closed separable subset fails to be Lipschitz retract M. This provides analogue the various classical and recent examples Banach spaces failing have linearly complemented subspaces prescribed smaller density character.

The class of strictly singular operators originating from the dual of a separable Banach space is written as an increasing union of ω1 subclasses which are defined using the Schreier sets. A question of J. Diestel, of whether a similar result can be stated for strictly cosingular operators, is studied.

In this article, we study a class of impulsive stochastic neutral partial functional differential equations in a real separable Hilbert space. By using Banach fixed point theorem, we give sufficient conditions for the existence and uniqueness of a mild solution. Also the exponential p-stability of a mild solution and its sample paths are obtained.