# Computer Sciences

## Optimal Eulerian modification of digraphs by addition of arcs

Тhe following problem is solved: given a directed graph, it is necessary to add to it a minimal number of arcs to obtain an Eulerian directed graph.

## Numerical Modelling and the Analysis of Impact of Distortions on OFDM/QAM-signal

In this work mathematical models of communication channels with various interferences, their influence on constellation diagrams’

points in systems with OFDM/QAM signals are considered, recommendations about channel monitoring are made.

## Numerical Modelling and the Analysis of Impact of Distortions on OFDM/QAM-signal

In this work mathematical models of communication channels with various interferences, their influence on constellation diagrams’

points in systems with OFDM/QAM signals are considered, recommendations about channel monitoring are made.

## Heuristic algorithm for the cardinality constrained portfolio optimization problem

In the paper we consider the cardinality constrained portfolio optimization problem. Constraint on the number of assets in portfolio leads to the mixed integer optimization problem. Effective frontier is constructed using the metaheuristic approach by genetic algorithm.

## Differential evolution algorithm for solving the portfolio optimization problem

In the paper we develop metaheuristic method based on differential evolution for finding efficient frontier in solving the portfolio optimisation problem for investor with non concave utility function which reflects asymmetric investor attitude to losses and gains.

## A Method of Routing Control in Queueing Networks with Changing Topology

Closed exponential queueing networks with changing topology are considered. A method of routing control in given type queueing networks is proposed.

## Simultaneous Approximation of Polynomial Functions and Its Derivatives by Feedforward Artificial Neural Networks with One Hidden Layer N. S.

In this paper we propose the algorithm for finding weights of feedforward artificial neural networks with one hidden layer to approximate polynomial functions and its derivatives with a given error. We use the rational sigmoidal function as a transfer function.

## Discrete Dynamical Systems Defined Geometrical Images of Automata

The object of study is the dynamic system defined by geometrical images of automata. The phase space of the system is determined by orthogonal and affine transformations of geometric images. Compositions of dynamical systems of a given type and their characteristics are studied.

## On Diagnostic Experiments for Fuzzy Automata

The concept of a generalized diagnostic experiment for fuzzy automata is introduced. A method constructing diagnostic experiments for fuzzy automata is proposed. The method is based on diagnostic tree structure. It is establish that the problem of diagnostic experiment synthesis is a multi-criteria optimization problem.

## Automata on algebraic structures

A survey of results obtained in investigations of automata determined over finite algebraic structures. The objects of research are automata over some finite ring, automata determined in terms of ideals, automata over varieties, and families of hash-functions determined by automata without output function. Computational security, complexity of simulation and homomorphisms of investigated automata are characterized.