Let Ω,Ω’ ⊂ ℝⁿ be domains and let f: Ω → Ω’ be a homeomorphism. We show that if the composition operator maps the Sobolev-Lorentz space to for some q ≠ n then f must be a locally bilipschitz mapping.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-sm221-3-1, author = {Stanislav Hencl and Lud\v ek Kleprl\'\i k and Jan Mal\'y}, title = {Composition operator and Sobolev-Lorentz spaces $WL^{n,q}$ }, journal = {Studia Mathematica}, volume = {223}, year = {2014}, pages = {197-208}, zbl = {1293.30050}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm221-3-1} }
Stanislav Hencl; Luděk Kleprlík; Jan Malý. Composition operator and Sobolev-Lorentz spaces $WL^{n,q}$ . Studia Mathematica, Tome 223 (2014) pp. 197-208. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm221-3-1/