A Cohen-Type Inequality for Jacobi-Sobolev Expansions
© Bujar Xh. Fejzullahu 2007
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.
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