In mathematics, the Besov space (named after Oleg Vladimirovich Besov) is a complete quasinormed space which is a Banach space when 1 ≤ p, q ≤ ∞. These spaces, as well as the similarly defined Triebel–Lizorkin spaces, serve to generalize more elementary function spaces such as Sobolev spaces and are effective at measuring regularity properties of functions.

Definition

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Several equivalent definitions exist. One of them is given below.

Let

 

and define the modulus of continuity by

 

Let n be a non-negative integer and define: s = n + α with 0 < α ≤ 1. The Besov space   contains all functions f such that

 

Norm

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The Besov space   is equipped with the norm

 

The Besov spaces   coincide with the more classical Sobolev spaces  .

If   and   is not an integer, then  , where   denotes the Sobolev–Slobodeckij space.

References

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  • Triebel, Hans (1992). Theory of Function Spaces II. doi:10.1007/978-3-0346-0419-2. ISBN 978-3-0346-0418-5.
  • Besov, O. V. (1959). "On some families of functional spaces. Imbedding and extension theorems". Dokl. Akad. Nauk SSSR (in Russian). 126: 1163–1165. MR 0107165.
  • DeVore, R. and Lorentz, G. "Constructive Approximation", 1993.
  • DeVore, R., Kyriazis, G. and Wang, P. "Multiscale characterizations of Besov spaces on bounded domains", Journal of Approximation Theory 93, 273-292 (1998).
  • Leoni, Giovanni (2017). A First Course in Sobolev Spaces: Second Edition. Graduate Studies in Mathematics. 181. American Mathematical Society. pp. 734. ISBN 978-1-4704-2921-8