Articlesticles

Modern Functional Analysis in Theory of Sequence Spaces and Matrix Transformations

Many concepts and theories in functional analysis have turned out to be powerful and widely used tools in operator theory, in particular in the theory of matrix transformations between sequences spaces in summability.

Eberhard Malkowsky

Strongly Singular Calderon-Zygmund Operators and their Commutators

In this paper, the authors obtain two kinds of endpoint estimates for strongly singular Calder´on-Zygmund operators. Moreover, the pointwise estimate for the sharp maximal function of commutators generated by strongly singular Calder´on- Zygmund operators and BMO functions is also established.

Yan Lin and Shanzhen Lu

Matrix Transformations between Sets of the form Wx and Operator Generators of Analytic Semigroups

In this paper we establish a relation between the notion of operators of analytic semigroups and matrix transformations from a set of sequences into w1.

Bruno De Malafosse
Eberhard Malkowsky 

Best Simultaneous Approximation in Metric Spaces

For a Banach space X and an increasing subadditive continuous function ' on [0,1) with '(0) = 0, let us denote by L '(I,X), the space of all X-valued '- integrable functions f : I ! X on a certain positive complete -finite measure space (I, P , μ, ) with R I ' kf(t)k dμ(t) < 1 and l '(X) =  (xk) : 1P k=1 ' kxkk < 1, xk 2 X  .

Sharifa Al-Sharif

Algebraic Models in Applied Research

Mathematical models can be used in several sciences as a tool to organize the research in such a way that the results could be transferred into other sciences. Here we go on with a method how to organise some results, which do not seem to have any relation with mathematics in a strictly algebraic way.

Thomas Vougiouklis
Penelope Kambaki

The Set of Values of Functional in the Classes of Functions having Integral Representation

This paper presents a certain method to determine the set of values of the functional J ( f ) ( ) ( ) ( ) 0 a z f k z n k k Σ= = defined on the family of analytic functions in the unit disc possessing an integral representation with kernel q(z,t) in the interval [α ,β ].

Hassan Baddour