On the convergence of Padé approximations for generalized Nevanlinna functions

M Derevyagin, V Derkach - Transactions of the Moscow Mathematical …, 2007 - ams.org
We study a stepwise algorithm for solving the indefinite truncated moment problem and
obtain the factorization of the matrix describing the solution of this problem into elementary …

Non-self-adjoint Jacobi matrices with a rank-one imaginary part

Y Arlinskiĭ, E Tsekanovskiĭ - Journal of Functional Analysis, 2006 - Elsevier
We develop direct and inverse spectral analysis for finite and semi-infinite non-self-adjoint
Jacobi matrices with a rank-one imaginary part. It is shown that given a set of n not …

Darboux transformations of Jacobi matrices and Padé approximation

M Derevyagin, V Derkach - Linear algebra and its applications, 2011 - Elsevier
Let J be a monic Jacobi matrix associated with the Cauchy transform F of a probability
measure. We construct a pair of the lower and upper triangular block matrices L and U such …

On a class of generalized Stieltjes continued fractions

V Derkach, I Kovalyov - Methods of Functional Analysis and …, 2015 - mfat.imath.kiev.ua
With each sequence of real numbers ${\mathbf s}=\{s_j\} _ {j= 0}^\infty $ two kinds of
continued fractions are associated,-the so-called $ P-$ fraction and a generalized Stieltjes …

The Schur algorithm for an indefinite Stieltjes moment problem

V Derkach, I Kovalyov - Mathematische Nachrichten, 2017 - Wiley Online Library
The nondegenerate truncated indefinite Stieltjes moment problem in the class of
generalized Stieltjes functions is considered. To describe the set of solutions of this problem …

Weyl functions of bounded quasi-selfadjoint operators and block operator Jacobi matrices

Y Arlinskiῐ, L Klotz - Acta Scientiarum Mathematicarum, 2010 - Springer
A bounded operator T in a separable Hilbert space ℌ is called quasi-selfadjoint if ker
(TT*)≠{0} and ℜ-quasi-selfadjoint if ℜ⊇ ran (TT*), where ℜ is a subspace of ℌ. An ℜ-quasi …

Darboux transformation of generalized Jacobi matrices

I Kovalyov - Methods of Functional Analysis and Topology, 2014 - mfat.imath.kiev.ua
Let $\mathfrak {J} $ be a monic generalized Jacobi matrix, ie a three-diagonal block matrix of
special form, introduced by M.~ Derevyagin and V.~ Derkach in 2004. We find conditions for …

[HTML][HTML] On Szegő's theorem for a nonclassical case

M Derevyagin, B Simanek - Journal of Functional Analysis, 2017 - Elsevier
In this paper we prove Szegő's Theorem for the case when a finite number of Verblunsky
coefficients lie outside the closed unit disk. Although a form of this result was already proved …

Borg-type theorems for generalized Jacobi matrices and trace formulas

MS Derevyagin - Methods of Functional Analysis and Topology, 2006 - mfat.imath.kiev.ua
The paper deals with two types of inverse spectral problems for the class of generalized
Jacobi matrices introduced in [9]. Following the scheme proposed in [5], we deduce analogs …

[HTML][HTML] On the relation between Darboux transformations and polynomial mappings

M Derevyagin - Journal of approximation theory, 2013 - Elsevier
Let dμ be a probability measure on [0,+∞) such that its moments are finite. Then the Cauchy–
Stieltjes transform S of dμ is a Stieltjes function, which admits an expansion into a Stieltjes …