The Nikolskĭi-Besov spaces B pq ( R ) ≡ B pq, 1 ≤ p, q ≤ ∞, α > 0, recently were described using the Caputo’s fractional derivative. Using the concept of weak fractional derivative, in this paper we reduces the characterization of B pq to the case B pq, where γ is any positive number strictly less than α.
