{ "id": "1809.09742", "version": "v1", "published": "2018-09-25T22:09:38.000Z", "updated": "2018-09-25T22:09:38.000Z", "title": "A Jarník-type theorem for a problem of approximation by cubic polynomials", "authors": [ "Alessandro Pezzoni" ], "categories": [ "math.NT" ], "abstract": "For a given decreasing positive real function $\\psi$, let $\\mathcal{A}_n(\\psi)$ be the set of real numbers for which there are infinitely many integer polynomials $P$ of degree up to $n$ such that $\\left\\lvert P(x) \\right\\rvert \\leq \\psi(\\operatorname{H}(P))$. A theorem by Bernik states that $\\mathcal{A}_n(\\psi)$ has Hausdorff dimension $\\frac{n+1}{w+1}$ in the special case $\\psi(r) = r^{-w}$, while a theorem by Beresnevich, Dickinson and Velani implies that the Hausdorff measure $\\operatorname{\\mathcal{H}}^g(\\mathcal{A}_n(\\psi))=\\infty$ when a certain series diverges. In this paper we prove the convergence counterpart of this result when $P$ has bounded discriminant, which leads to a complete solution when $n = 3$ and $\\psi(r) = r^{-w}$.", "revisions": [ { "version": "v1", "updated": "2018-09-25T22:09:38.000Z" } ], "analyses": { "subjects": [ "11J83" ], "keywords": [ "cubic polynomials", "jarník-type theorem", "approximation", "complete solution", "decreasing positive real function" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }