Separation of Boundary Singularities for Holomorphic Generators

We prove a theorem on separation of boundary null points for generators of continuous semigroups of holomorphic self-mappings of the unit disk in the complex plane. Our construction demonstrates the existence and importance of a particular role of the binary operation $\circ$ given by $1 / f \circ g = 1/f + 1/g$ on generators

Autoresonance in a Dissipative System

We study the autoresonant solution of Duffing's equation in the presence of dissipation. This solution is proved to be an attracting set. We evaluate the maximal amplitude of the autoresonant solution and the time of transition from autoresonant growth of the amplitude to the mode of fast oscillations. Analytical results are illustrated by numerical simulations.Comment: 22 pages, 3 figure

Boundary Value Problems with Non-Local Conditions

We describe a new algebra of boundary value problems which contains Lopatinskii elliptic as well as Toeplitz type conditions. These latter are necessary, if an analogue of the Atiyah-Bott obstruction does not vanish. Every elliptic operator is proved to admit up to a stabilisation elliptic conditions of such a kind. Corresponding boundary value problems are then Fredholm in adequate scales of spaces. The crucial novelty consists of the new type of weighted Sobolev spaces which fit well to the nature of pseudodifferential operators

An Explicit Carleman Formula for the Dolbeault Cohomology

Изучаются формулы, которые восстанавливают класс когомологий Дольбо в областях из Cn по их значениям на открытой части границы. Они называются формулами Карлемана по имени математика, который нашел их первым в простейшем случае для проблемы аналитического продолжения. Для функций многих комплексных переменных наш подход дает простейшую формулу для аналитического продолжения с части границы. Проблема продолжения для когомологий Дольбо неожиданно устойчива в положительных классах, если начальные данные даются на вогнутой части границы. В этом случае дается точная формула продолжения.We study formulas which recover a Dolbeault cohomology class in a domain of Cn through its values on an open part of the boundary. These are called Carleman formulas after the mathematician who first used such a formula for a simple problem of analytic continuation. For functions of several complex variables our approach gives the simplest formula of analytic continuation from a part of the boundary. The extension problem for the Dolbeault cohomology proves surprisingly to be stable at positive steps if the data are given on a concave piece of the boundary. In this case we construct an explicit extension formula