The use of the isometry of function spaces with different numbers of variables in the theory of approximation of functions

  • D.M. Bushev Lesya Ukrainka Volyn National University, 13 Voli avenue, 43025, Lutsk, Ukraine
  • F.G. Abdullayev Mersin University, Çiftlikköy, Mersin Ünv., 33110 Yenişehir, Mersin, Turkey
  • I.V. Kal'chuk Lesya Ukrainka Volyn National University, 13 Voli avenue, 43025, Lutsk, Ukraine
  • M. Imashkyzy Kyrgyz-Turkish Manas University, 56 Mira avenue, 720044, Bishkek, Kyrgyzstan
Keywords: delta-like kernel, isometry, space of convolutions, approximative characteristic
Published online: 2021-12-30

Abstract


In the work, we found integral representations for function spaces that are isometric to spaces of entire functions of exponential type, which are necessary for giving examples of equality of approximation characteristics in function spaces isometric to spaces of non-periodic functions. Sufficient conditions are obtained for the nonnegativity of the delta-like kernels used to construct isometric function spaces with various numbers of variables.

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How to Cite
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Bushev D., Abdullayev F., Kal’chukI., Imashkyzy M. The Use of the Isometry of Function Spaces With Different Numbers of Variables in the Theory of Approximation of Functions. Carpathian Math. Publ. 2021, 13 (3), 805-817.