Abstract

The question on affine Riesz basis of Walsh affine systems is considered. An affine Riesz basis is constructed, generated by a continuous periodic function that belongs to the space on the real line, which has a derivative almost everywhere; in connection with the construction of this example, we note that the functions of the classical Walsh system suffer a discontinuity and their derivatives almost vanish everywhere. A method of regularization (improvement of differential properties) of the generating function of Walsh affine system is proposed, and a criterion for an affine Riesz basis for a regularized generating function that can be represented as a sum of a series in the Rademacher system is obtained.

Highlights

  • Let {0,1}k k 0be the set of all finite multi-indices ( 0,( 0, l 1), denote by: Iraqi Journal of Science, 2021, Vol 62, No 12, pp: 4875-4884( 0, k 1, 0, l 1) W W 0 W k 1( 0, k 1), The first is the operator W k 1 and the last is W 0

  • Rademacher system was first introduced by the German mathematician Hans Rademacher in 1922

  • Sarsenbi, and Terekhin [12] studied an affine Bessel sequences in connection with the spectral theory and the multishift structure in Hilbert space

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Summary

Walsh generated by function f

Rademacher system was first introduced by the German mathematician Hans Rademacher in 1922. Rademacher system is an incomplete orthonormal system in L2[0,1]. Definition (1.2)[2]: Let r be the function defined on [0,1) by : 1, 0 t 1/ 2

Rademacher system
Riesz basis if there exists an orthonormal basis
Walsh system
Hence we find that g
It is clear that
Conclusions
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