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On an entire function represented by multiple Dirichlet series

Lakshika Chutani (2021)

Mathematica Bohemica

Consider the space L of entire functions represented by multiple Dirichlet series that becomes a non uniformly convex Banach space which is also proved to be dense, countable and separable. Continuing further, for the given space L the characterization of bounded linear transformations in terms of matrix and characterization of linear functional has been obtained.

On an estimate of a functional in the class of holomorphic univalent functions

Zbigniew Jerzy Jakubowski, Krystyna Zyskowska (1993)

Mathematica Bohemica

Let S denote the class of functions f ( x ) = z + a 2 z 2 + a 3 z 3 + ... univalent and holomorphic in the unit disc Δ = { z : z < 1 } . In the paper we obtain an estimate of the functional a 3 - c a 2 2 + c a 2 n in the class S for arbitrarily fixed x 𝐑 and n = 1 , 2 , 3 , ... . Hence, for some special values of the parameters, we obtain estimates of several interesting functionals and numerous applications. A few open problems of a similar type are also formulated.

On an extremal problem

Krystyna Zyskowska (1995)

Mathematica Bohemica

Let S denote the class of functions f ( z ) = z + a 2 z 2 + a 3 z 3 + ... univalent and holomorphic in the unit disc 𝛥 = { z | z | < 1 } . In the paper we obtain a sharp estimate of the functional | a 3 - α a 2 2 | + α | a 2 | 2 in the class S for an arbitrary α .

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