{ "id": "1709.06802", "version": "v1", "published": "2017-09-20T10:37:02.000Z", "updated": "2017-09-20T10:37:02.000Z", "title": "Accessible Parts of Boundary for Simply Connected Domains", "authors": [ "Pekka Koskela", "Debanjan Nandi", "Artur Nicolau" ], "comment": "11 pages", "categories": [ "math.CA", "math.CV" ], "abstract": "For a bounded simply connected domain $\\Omega\\subset\\mathbb{R}^2$, any point $z\\in\\Omega$ and any $0<\\alpha<1$, we give a lower bound for the $\\alpha$-dimensional Hausdorff content of the set of points in the boundary of $\\Omega$ which can be joined to $z$ by a John curve with John constant depending only on $\\alpha$, in terms of the distance of $z$ to $\\partial\\Omega$. In fact this set in the boundary contains the intersection $\\partial\\Omega_z\\cap\\partial\\Omega$ of the boundary of a John sub-domain $\\Omega_z$ of $\\Omega$, centered at $z$, with the boundary of $\\Omega$. This may be understood as a quantitative version of a result of Makarov. This estimate is then applied to obtain the pointwise version of a weighted Hardy inequality.", "revisions": [ { "version": "v1", "updated": "2017-09-20T10:37:02.000Z" } ], "analyses": { "subjects": [ "30C35", "26D15" ], "keywords": [ "simply connected domain", "accessible parts", "dimensional hausdorff content", "john constant", "weighted hardy inequality" ], "note": { "typesetting": "TeX", "pages": 11, "language": "en", "license": "arXiv", "status": "editable" } } }