On a theorem of Nehari and quasidiscs.
We characterize the existence of the solutions of the truncated moments problem in several real variables on unbounded supports by the existence of the maximum of certain concave Lagrangian functions. A natural regularity assumption on the support is required.
Let f be a quadratic map (more generally, , d > 1) of the complex plane. We give sufficient conditions for f to have no measurable invariant linefields on its Julia set. We also prove that if the series converges absolutely, then its sum is non-zero. In the proof we use analytic tools, such as integral and transfer (Ruelle-type) operators and approximation theorems.
In this paper we obtain various approximation theorems by means of k-positive linear operators defined on the space of all analytic functions on a bounded domain of the complex plane.
Consider the space 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 the characterization of bounded linear transformations in terms of matrix and characterization of linear functional has been obtained.
Let denote the class of functions univalent and holomorphic in the unit disc . In the paper we obtain an estimate of the functional in the class for arbitrarily fixed and . 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.
Let denote the class of functions univalent and holomorphic in the unit disc . In the paper we obtain a sharp estimate of the functional in the class for an arbitrary .