Translated from the Russian.

Includes bibliographies.

Harmonic analysis on adic Lie groups;Toeplitz operators and division by an inner function in some spaces of analytic functions;Logarithmic subharmonicity of a form of an analytic expanding matrix-valued function;Meromorphic solutions of equations of Briot-Bouquet type;The generalized Robin problem and a variational method for solving it;Some properties of interpolation processes in spaces of continuous functions;On multipliers of double Fourier series;On the conjugation operator in spaces of H�older type;Some optimization problems connected with the construction of stable dynamical systems by Lyapunov's second method;On solitons with Hopf index;Complete integrability of some classical Hamiltonian systems;A conjecture about entropy;Approximation by polynomials of solutions of a class of Hammerstein integral equations