103 citations · 173 across the 15 of their papers we have counts for
15 papers
Unitary boundary pairs for isometric operators in Pontryagin spaces and generalized coresolvents
D. Baidiuk, V. Derkach, S. Hassi
An isometric operator V in a Pontryagin space H is called standard, if its domain and the range are nondegenerate subspaces in H. A description of coresolvents for standard isometr…
Full indefinite Stieltjes moment problem and Padé approximants
V. Derkach, I. Kovalyov
Full indefinite Stieltjes moment problem is studied via the step-by-step Schur algorithm. Naturally associated with indefinite Stieltjes moment problem are generalized Stieltjes co…
Generalized boundary triples, Weyl functions and inverse problems
Vladimir Derkach, Seppo Hassi, Mark Malamud
With a closed symmetric operator in a Hilbert space a triple of a Hilbert space and two abstract trace operators $Γ_…
Schur algorithm for Stieltjes indefinite moment problem
Vladimir Derkach, Ivan Kovalyov
Nondegenerate truncated indefinite Stieltjes moment problem in the class of generalized Stieltjes functions is considered. To describe the set of solutions of th…
Invariance theorems for Nevanlinna families
Vladimir Derkach, Seppo Hassi, Mark Malamud
A complex function is called a Herglotz-Nevanlinna function if it is holomorphic in the upper half-plane and maps into itself. By a maximum p…
Weyl function of a Hermitian operator and its connection with characteristic function
Vladimir Derkach, Mark Malamud
Let be a densely defined symmetric operator with equal deficiency indices in a Hilbert space. We introduce the notion of a Weyl function of corresponding to an ordin…