Let 1 ≤ p < ∞, k ≥ 1, and let Ω ⊂ ℝⁿ be an arbitrary open set. We prove a converse of the Calderón-Zygmund theorem that a function possesses an derivative of order k at almost every point x ∈ Ω and obtain a characterization of the space . Our method is based on distributional arguments and a pointwise inequality due to Bojarski and Hajłasz.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-cm119-1-11, author = {David Swanson}, title = {A characterization of Sobolev spaces via local derivatives}, journal = {Colloquium Mathematicae}, volume = {120}, year = {2010}, pages = {157-167}, zbl = {1206.46036}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm119-1-11} }
David Swanson. A characterization of Sobolev spaces via local derivatives. Colloquium Mathematicae, Tome 120 (2010) pp. 157-167. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm119-1-11/