Zobrazeno 1 - 10
of 27
pro vyhledávání: '"Sergey M. Zagorodnyuk"'
Autor:
Sergey M. Zagorodnyuk
Publikováno v:
Surveys in Mathematics and its Applications, Vol 18 (2023), Pp 73-82 (2023)
In this paper we consider the following moment problem: find a positive Borel measure μ on ℂ subject to conditions ∫ zn dμ = sn, n∈ℤ+, where sn are prescribed complex numbers (moments). This moment problem may be viewed (informally) as an e
Externí odkaz:
https://doaj.org/article/438aec7b91e241849dae7555dbc34647
Autor:
Sergey M. Zagorodnyuk
Publikováno v:
Symmetry, Integrability and Geometry: Methods and Applications, Vol 7, p 016 (2011)
In this paper we obtain necessary and sufficient conditions for a linear bounded operator in a Hilbert space H to have a three-diagonal complex symmetric matrix with non-zero elements on the first sub-diagonal in an orthonormal basis in H. It is show
Externí odkaz:
https://doaj.org/article/5b824b9e2481438ca120e528f16c23c3
Autor:
Sergey M. Zagorodnyuk
Publikováno v:
Advances in Operator Theory. 7
We study the operator $\mathcal{A}$ of multiplication by an independent variable in a matrix Sobolev space $W^2(M)$. In the cases of finite measures on $[a,b]$ with $(2\times 2)$ and $(3\times 3)$ real continuous matrix weights of full rank it is sho
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::5b268d08a1ff8e536c5936f4ad461919
https://doi.org/10.1007/s43036-022-00221-1
https://doi.org/10.1007/s43036-022-00221-1
Autor:
Sergey M. Zagorodnyuk
For every system $\{ p_n(z) \}_{n=0}^\infty$ of OPRL or OPUC, we construct Sobolev orthogonal polynomials $y_n(z)$, with explicit integral representations involving $p_n$. Two concrete families of Sobolev orthogonal polynomials (depending on an arbit
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::8adfc772805e73412ef20e55fd59b06f
http://arxiv.org/abs/2006.11554
http://arxiv.org/abs/2006.11554
Autor:
Sergey M. Zagorodnyuk
Publikováno v:
Volume: 3, Issue: 2 75-84
Constructive Mathematical Analysis
Constructive Mathematical Analysis
In this paper we study the following family of hypergeometric polynomials: $y_n(x) = \frac{ (-1)^\rho }{ n! } x^n {}_2 F_0(-n,\rho;-;-\frac{1}{x})$, depending on a parameter $\rho\in\mathbb{N}$. Differential equations of orders $\rho+1$ and $2$ for t
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::287593fe9461db99a0f1b4485ecb1975
http://arxiv.org/abs/2002.06428
http://arxiv.org/abs/2002.06428
Autor:
Sergey M. Zagorodnyuk
Publikováno v:
Journal of Difference Equations and Applications. 24:1664-1684
In this paper we study various difference equations related to Jacobi-type pencils. By a Jacobi-type pencil one means the following pencil: $J_5 - \lambda J_3$, where $J_3$ is a Jacobi matrix and $J_5$ is a semi-infinite real symmetric five-diagonal
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::6d2a73c47e33f959477ee05a7603fc8f
https://doi.org/10.1080/10236198.2018.1515929
https://doi.org/10.1080/10236198.2018.1515929
Autor:
Sergey M. Zagorodnyuk
Publikováno v:
Ukrainian Mathematical Journal. 68:1353-1365
We study a generalization of a class of orthonormal polynomials on the real axis. These polynomials satisfy the relation $$ \left({J}_5-\uplambda {J}_3\right)\overrightarrow{p}\left(\uplambda \right)=0, $$ where J 3 is a Jacobi matrix, J 5 is a semii
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::7bb65799c96d76a7bba34aaa19cc08d0
https://doi.org/10.1007/s11253-017-1300-3
https://doi.org/10.1007/s11253-017-1300-3
Autor:
Sergey M. Zagorodnyuk
Publikováno v:
Journal of Approximation Theory. 250:105337
In this paper we propose a way to construct classical type Sobolev orthogonal polynomials. We consider two families of hypergeometric polynomials: ${}_2 F_2(-n,1;q,r;x)$ and ${}_3 F_2(-n,n-1+a+b,1;a,c;x)$ ($a,b,c,q,r>0$, $n=0,1,...$), which generaliz
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::bb64bf12ee2c50e71d40fdc1ee6a57e7
https://doi.org/10.1016/j.jat.2019.105337
https://doi.org/10.1016/j.jat.2019.105337
Autor:
Sergey M. Zagorodnyuk
Publikováno v:
Concrete Operators, Vol 6, Iss 1, Pp 1-19 (2019)
We study the truncated multidimensional moment problem with a general type of truncations. The operator approach to the moment problem is presented. A way to construct atomic solutions of the moment problem is indicated.
24 pages
24 pages
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::963e855db6bc482392460db3dc528680
http://arxiv.org/abs/1802.06122
http://arxiv.org/abs/1802.06122
Autor:
Sergey M. Zagorodnyuk
Publikováno v:
Sarajevo Journal of Mathematics. 11:65-72
In this paper, we shall characterize the components of the polar decomposition for an arbitrary $J$-unitary operator in a Hilbert space. This characterization has a quite different structure as that for complex symmetric and complex skew-symmetric op
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::47f476f0dc8582516dbe40242a6d21ad
https://doi.org/10.5644/sjm.11.1.05
https://doi.org/10.5644/sjm.11.1.05