On the properties for families of function classes over harmonic intervals and their embedding relation with Besov spaces


Yessenbayeva G.A. Serikova L.A.
2025E.A. Buketov Karaganda University Publish house

Bulletin of the Karaganda University. Mathematics Series
2025#118Issue 2260 - 268 pp.

The article is dedicated to the issues of studying the approximation of functions by trigonometric polynomials with a spectrum from special sets. In this paper, these special sets are harmonic intervals. To study the approximation of functions over harmonic intervals, families of function classes have been created, designed as a subsidiary tool. These families of function classes are characterized through the best approximations of functions by trigonometric polynomials over such sets and are used in the research. For these families of function classes, their properties and the connection with classical Besov spaces are shown. The results of the study are presented in the form of theorems and lemmas. In carrying out the research presented in the article, the main apparatus for proving theorems are the fundamentals of approximation theory, the method of real interpolation of spaces, and the fundamentals of the theory of embedding classes of functions and functional spaces. The article is destined for mathematicians and can be used by researchers and specialists whose interests lie in the indicated areas of mathematics.

Besov spaces , best approximation of a function by trigonometric polynomials with a spectrum from harmonic intervals , embedding theorems , family of classes of functions , harmonic interval , spectrum

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Department of Algebra, Mathematical Logic and Geometry Named After Professor Mustafin T.G., Karaganda Bukenov University, 28 Universitetskaya street, Karaganda, 100028, Kazakhstan
Educational Program “6B05401-Mathematics”, Faculty of Mathematics and Information Technology, Karaganda Bukenov University, 28 Universitetskaya street, Karaganda, 100028, Kazakhstan

Department of Algebra
Educational Program “6B05401-Mathematics”

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