# Mathematics

## The problem of Leont'ev on entire functions of completely regular growth

We consider an entire function of exponential type with all its zeros are simple and form a sequence with the index condensation zero. On the set of zeros a function of its derivative is growing quickly. Required to determine whether original function have complete regularity of growth. This problem, which arose in the theory of representation of analytic functions by exponential series was posed by A. F. Leontiev more than forty years ago and has not yet been solved.

## A U-set for system of character of the zero-dimensional group under convergent over cubes

In this work we consider system of characters of the compact zero-dimensional group G and study uniqueness sets forN-fold multiple series for system of character a zero-dimensional group under convergent over cubes (in other words, U-sets). We proof that every finite set is a U-set and show that countable set with only one limit point is a U-set.

## To a Solution of the Inhomogeneous Riemann–Hilbert Boundary Value Problem for Analytic Function in Multiconnected Circular Domain in a Special Case

The author offers a new approach to solution of the Riemann–Hilbert boundary value problem for analytic function in multiconnected circular domain. This approach is based on construction of solution of corresponding homogeneous problem, when analytic in domain function is being defined by known boundary values of its argument. The author considers a special case of a problem when the index of a problem is more than zero and on unit of less order of connectivity of domain. Resolvability of a problem depends on number of solutions of some system of the linear algebraic equations.

## Mathematical modelling of loss of stability of system of step and homogeneous cores at blow about the rigid barrier Tymoshenko's method

Mathematical modeling of longitudinal elastic central blow of system of step and homogeneous cores about a rigid barrier is carried out, at not holding communications by a solution of the wave equation by Dalamber's method. On the basis of the law of conservation of energy by Tymoshenko's method the size of critical compressing loading according to which, the size of critical pretonic speed leading to loss of stability of considered rod system further pays off.

## Oval lines of the hyperbolic plane of positive curvature

The classification of real nondegenerate second-order lines of the hyperbolic plane H^ of positive curvature is obtained. It is proved that the basic geometric covariants and the property of line to be convex (nonconvex) determine seven types of intrinsic oval lines and eight types of nonintrinsic oval line on H^. For every intrinsic oval lines the associate projective frame is constructed and the canonical equation is received.

## Lebesgue functions for Haar system on compact zero-dimensional group

In this article we discuss Lebesgue functions for Haar system on compact zero-dimensional group. We find cases when they are constant, also we find two-sided estimates for Lebesgue functions.

## Refined asymptotic formulas for eigenvalues and eigenfunctions of the Dirac system with nondifferentiable potential

This paper investigates the Dirac system with the continuous potential. Asymptotic formulas for the eigenvalues (including refined) and eigenfunctions are established. As an application we obtain a theorem P. Dzhakova and B. S. Mityagin on the Riesz bases with brackets.

## Almost contact metric structures defined by connection over distribution with admissible Finslerian metric

The notion of the intrinsic connection and the extended connection of an almost contact metric manifold D with admissible Finslerian metric is introduced and studied. Using this and the extended connection on D as on the total space of a vector bundle, an almost contact metric structure is defined and investigated.

## The theorem on existence and uniqueness of the solution of one boundary value problem in strip for degenerate elliptic equations of higher order

Theorem on the existence and uniqueness of the solution of the boundary value problem in the strip for one degenerate elliptic equations of higher order, which degenerate on one of boundary of the strip in the third-order equation by one variable, is proved.

## The correctness of the Dirichlet problem in the cylindric domain for equation Laplase

Thes paper shows is uniquely solvable solitions the Dirichlet problem in the cylindric domain for equation Laplase.