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  • Research Article
  • Open Access

A Cohen-Type Inequality for Jacobi-Sobolev Expansions

Journal of Inequalities and Applications20082007:093815

  • Received: 21 August 2007
  • Accepted: 11 December 2007
  • Published:


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.


  • Fourier Expansion
  • Orthogonal Expansion
  • Orthonormal Polynomial
  • Jacobi Measure


Authors’ Affiliations

Faculty of Mathematics and Sciences, University of Prishtina, Mother Teresa 5, Prishtina, Kosovo, 10000, Serbia


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© Bujar Xh. Fejzullahu 2007

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