On factorization and partial indices of unitary matrix-functions of one class.
On the solution of Nevanlinna Pick problem with selfadjoint extensions of symmetric linear relations in Hilbert space.
On two-sided interpolation for upper triangular matrices.
One-dimensional graph perturbations of selfadjoint relations.
Reconstruction of algebraic sets from dynamic moments
We discuss an exact reconstruction algorithm for time expanding semi-algebraic sets given by a single polynomial inequality. The theoretical motivation comes from the classical -problem of moments, while some possible applications to 2D fluid moving boundaries are sketched. The proofs rely on an adapted co-area theorem and a Hankel form minimization.
Sous-normalité jointe non bornée et applications
T. Trent gave a new characterization of subnormality for an operator on a Hilbert space. T. Bînzar and D. Păunescu generalized this condition to commuting triples of operators. Here, we give an n-variable unbounded version of the above results. Theorems of this kind have also been obtained by Z. J. Jabłoński and J. Stochel.
Spectral versus classical Nevanlinna-Pick interpolation in dimension two.
Stieltjes moment problem in general Gelfand-Shilov spaces
The Stieltjes moment problem is studied in the framework of general Gelfand-Shilov spaces, subspaces of the space of rapidly decreasing smooth complex functions, which are defined by imposing suitable bounds on their elements in terms of a given sequence M. Necessary and sufficient conditions on M are stated for the problem to have a solution, sometimes coming with linear continuous right inverses of the moment map, sending a function to the sequence of its moments. On the way, some results on the...
Sufficient conditions for boundedness of convolution operators in rearrangement-invariant spaces.
Sulla interpolazione di operatori compatti
The truncated matrix trigonometric moment problem with an open gap
This paper is a continuation of our previous investigations on the truncated matrix trigonometric moment problem in Ukrainian Math. J., 2011, 63, no. 6, 786-797, and Ukrainian Math. J., 2013, 64, no. 8, 1199- 1214. In this paper we shall study the truncated matrix trigonometric moment problem with an additional constraint posed on the matrix measure MT(δ), δ ∈ B(T), generated by the seeked function M(x): MT(∆) = 0, where ∆ is a given open subset of T (called a gap). We present necessary and sufficient...
The 'Window Problem' for Series of Complex Exponentials.
Two sandwich theorems for linear operators and the moment problem.
Uniqueness condition for the Pick problem.
Unitary extensions of isometries, generalized interpolation and band extensions
The aim of this paper is to give a very brief account of some applications of the method of unitary extensions of isometries to interpolation and extension problems.