Open Access

A Cohen-Type Inequality for Jacobi-Sobolev Expansions

Journal of Inequalities and Applications20082007:093815

DOI: 10.1155/2007/93815

Received: 21 August 2007

Accepted: 11 December 2007

Published: 6 February 2008


Let be the Jacobi measure supported on the interval [-1, 1]. Let us introduce the Sobolev-type inner product , where . In this paper we prove a Cohen-type inequality for the Fourier expansion in terms of the orthonormal polynomials associated with the above Sobolev inner product. We follow Dreseler and Soardi (1982) and Markett (1983) papers, where such inequalities were proved for classical orthogonal expansions.


Authors’ Affiliations

Faculty of Mathematics and Sciences, University of Prishtina


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© Bujar Xh. Fejzullahu 2007

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