Finite-infinite range inequalities in the complex plane

Let E⫅C be closed, ω be a suitable weight function on E, σ be a positive Borel measure on E. We discuss the conditions on ω and σ which ensure the existence of a fixed compact subset K of E with the following property. For any p, 0<P≤∞, there exist positive constants c1, c2 depending only on E, ω...

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Main Author: H. N. Mhaskar
Format: Article
Language:English
Published: Wiley 1991-01-01
Series:International Journal of Mathematics and Mathematical Sciences
Subjects:
Online Access:http://dx.doi.org/10.1155/S0161171291000868
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author H. N. Mhaskar
author_facet H. N. Mhaskar
author_sort H. N. Mhaskar
collection DOAJ
description Let E⫅C be closed, ω be a suitable weight function on E, σ be a positive Borel measure on E. We discuss the conditions on ω and σ which ensure the existence of a fixed compact subset K of E with the following property. For any p, 0<P≤∞, there exist positive constants c1, c2 depending only on E, ω, σ and p such that for every integer n≥1 and every polynomial P of degree at most n, ∫E\K|ωnP|pdσ≤c1exp(−c2n)∫K|ωnP|pdσ. In particular, we shall show that the support of a certain extremal measure is, in some sense, the smallest set K which works. The conditions on σ are formulated in terms of certain localized Christoffel functions related to σ.
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series International Journal of Mathematics and Mathematical Sciences
spelling doaj-art-3087ea6ac0d847e3b01c8760544c43192025-02-03T01:24:18ZengWileyInternational Journal of Mathematics and Mathematical Sciences0161-17121687-04251991-01-0114462563810.1155/S0161171291000868Finite-infinite range inequalities in the complex planeH. N. Mhaskar0Department of Mathematics, California State University, Los Angeles 90032, California, USALet E⫅C be closed, ω be a suitable weight function on E, σ be a positive Borel measure on E. We discuss the conditions on ω and σ which ensure the existence of a fixed compact subset K of E with the following property. For any p, 0<P≤∞, there exist positive constants c1, c2 depending only on E, ω, σ and p such that for every integer n≥1 and every polynomial P of degree at most n, ∫E\K|ωnP|pdσ≤c1exp(−c2n)∫K|ωnP|pdσ. In particular, we shall show that the support of a certain extremal measure is, in some sense, the smallest set K which works. The conditions on σ are formulated in terms of certain localized Christoffel functions related to σ.http://dx.doi.org/10.1155/S0161171291000868finite-infinite range inequalitiesorthogonal polynomials weighted polynomialsNikolskii inequalities.
spellingShingle H. N. Mhaskar
Finite-infinite range inequalities in the complex plane
International Journal of Mathematics and Mathematical Sciences
finite-infinite range inequalities
orthogonal polynomials
weighted polynomials
Nikolskii inequalities.
title Finite-infinite range inequalities in the complex plane
title_full Finite-infinite range inequalities in the complex plane
title_fullStr Finite-infinite range inequalities in the complex plane
title_full_unstemmed Finite-infinite range inequalities in the complex plane
title_short Finite-infinite range inequalities in the complex plane
title_sort finite infinite range inequalities in the complex plane
topic finite-infinite range inequalities
orthogonal polynomials
weighted polynomials
Nikolskii inequalities.
url http://dx.doi.org/10.1155/S0161171291000868
work_keys_str_mv AT hnmhaskar finiteinfiniterangeinequalitiesinthecomplexplane