{ "id": "2004.10682", "version": "v1", "published": "2020-04-22T16:35:23.000Z", "updated": "2020-04-22T16:35:23.000Z", "title": "Sobolev functions without compactly supported approximations", "authors": [ "Giona Veronelli" ], "comment": "10 pages. Comments are welcome", "categories": [ "math.AP", "math.DG", "math.FA" ], "abstract": "A basilar property and a useful tool in the theory of Sobolev spaces is the density of smooth compactly supported functions in the space $W^{k,p}(\\R^n)$ (i.e. the functions with weak derivatives of orders $0$ to $k$ in $L^p$). On Riemannian manifolds, it is well known that the same property remains valid under suitable geometric assumptions. However, on a complete non-compact manifold it can fail to be true in general, as we prove in this paper.", "revisions": [ { "version": "v1", "updated": "2020-04-22T16:35:23.000Z" } ], "analyses": { "subjects": [ "46E35", "53C20" ], "keywords": [ "compactly supported approximations", "sobolev functions", "property remains valid", "complete non-compact manifold", "smooth compactly supported functions" ], "note": { "typesetting": "TeX", "pages": 10, "language": "en", "license": "arXiv", "status": "editable" } } }