{ "id": "1812.00817", "version": "v1", "published": "2018-11-30T17:38:29.000Z", "updated": "2018-11-30T17:38:29.000Z", "title": "Extension criterions for homogeneous Sobolev space of functions of one variable", "authors": [ "Pavel Shvartsman" ], "comment": "53 pages. arXiv admin note: substantial text overlap with arXiv:1808.01467, arXiv:1710.07826", "categories": [ "math.FA" ], "abstract": "For each $p>1$ and each positive integer $m$ we give intrinsic characterizations of the restriction of the homogeneous Sobolev space $L^m_p(R)$ to an arbitrary closed subset $E$ of the real line. We show that the classical one dimensional Whitney's extension operator is \"universal\" for the scale of $L^m_p(R)$ spaces in the following sense: for every $p\\in(1,\\infty]$ it provides almost optimal $L^m_p$-extensions of functions defined on $E$. The operator norm of this extension operator is bounded by a constant depending only on $m$. This enables us to prove several constructive $L^m_p$-extension criterions expressed in terms of $m^{th}$ order divided differences of functions.", "revisions": [ { "version": "v1", "updated": "2018-11-30T17:38:29.000Z" } ], "analyses": { "subjects": [ "46E35" ], "keywords": [ "homogeneous sobolev space", "extension criterions", "dimensional whitneys extension operator", "intrinsic characterizations", "order divided differences" ], "note": { "typesetting": "TeX", "pages": 53, "language": "en", "license": "arXiv", "status": "editable" } } }