Ukrainian Mathematical Journal

, Volume 54, Issue 12, pp 1943–1957 | Cite as

On the Best Polynomial Approximations of 2π-Periodic Functions and Exact Values of n-Widths of Functional Classes in the Space L2

  • S. B. Vakarchuk


To solve extremal problems of approximation theory in the space L2, we use τ-moduli introduced by Ivanov. We determine the exact values of constants in Jackson-type inequalities and the exact values of n-widths of functional classes determined by these moduli.


Functional Classis Approximation Theory Extremal Problem Polynomial Approximation 
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Copyright information

© Plenum Publishing Corporation 2002

Authors and Affiliations

  • S. B. Vakarchuk
    • 1
  1. 1.Ukrainian Academy of Customs ServiceDnepropetrovsk

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