{"title":"Decomposing the Complement of the Union of Cubes and Boxes in Three Dimensions","authors":"","doi":"10.1007/s00454-024-00632-2","DOIUrl":null,"url":null,"abstract":"<h3>Abstract</h3> <p>Let <span> <span>\\(\\mathcal {C}\\)</span> </span> be a set of <em>n</em> axis-aligned cubes of arbitrary sizes in <span> <span>\\({\\mathbb R}^3\\)</span> </span> in general position. Let <span> <span>\\(\\mathcal {U}:=\\mathcal {U}(\\mathcal {C})\\)</span> </span> be their union, and let <span> <span>\\(\\kappa \\)</span> </span> be the number of vertices on <span> <span>\\(\\partial \\mathcal {U}\\)</span> </span>; <span> <span>\\(\\kappa \\)</span> </span> can vary between <em>O</em>(1) and <span> <span>\\(\\Theta (n^2)\\)</span> </span>. We present a partition of <span> <span>\\(\\mathop {\\textrm{cl}}({\\mathbb R}^3\\setminus \\mathcal {U})\\)</span> </span> into <span> <span>\\(O(\\kappa \\log ^4 n)\\)</span> </span> axis-aligned boxes with pairwise-disjoint interiors that can be computed in <span> <span>\\(O(n \\log ^2 n + \\kappa \\log ^6 n)\\)</span> </span> time if the faces of <span> <span>\\(\\partial \\mathcal {U}\\)</span> </span> are pre-computed. We also show that a partition of size <span> <span>\\(O(\\sigma \\log ^4 n + \\kappa \\log ^2 n)\\)</span> </span>, where <span> <span>\\(\\sigma \\)</span> </span> is the number of input cubes that appear on <span> <span>\\(\\partial \\mathcal {U}\\)</span> </span>, can be computed in <span> <span>\\(O(n \\log ^2 n + \\sigma \\log ^8 n + \\kappa \\log ^6 n)\\)</span> </span> time if the faces of <span> <span>\\(\\partial \\mathcal {U}\\)</span> </span> are pre-computed. The complexity and runtime bounds improve to <span> <span>\\(O(n\\log n)\\)</span> </span> if all cubes in <span> <span>\\(\\mathcal {C}\\)</span> </span> are congruent and the faces of <span> <span>\\(\\partial \\mathcal {U}\\)</span> </span> are pre-computed. Finally, we show that if <span> <span>\\(\\mathcal {C}\\)</span> </span> is a set of arbitrary axis-aligned boxes in <span> <span>\\({\\mathbb R}^3\\)</span> </span>, then a partition of <span> <span>\\(\\mathop {\\textrm{cl}}({\\mathbb R}^3\\setminus \\mathcal {U})\\)</span> </span> into <span> <span>\\(O(n^{3/2}+\\kappa )\\)</span> </span> boxes can be computed in time <span> <span>\\(O((n^{3/2}+\\kappa )\\log n)\\)</span> </span>, where <span> <span>\\(\\kappa \\)</span> </span> is, as above, the number of vertices in <span> <span>\\(\\mathcal {U}(\\mathcal {C})\\)</span> </span>, which now can vary between <em>O</em>(1) and <span> <span>\\(\\Theta (n^3)\\)</span> </span>.</p>","PeriodicalId":0,"journal":{"name":"","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"","FirstCategoryId":"100","ListUrlMain":"https://doi.org/10.1007/s00454-024-00632-2","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
Let \(\mathcal {C}\) be a set of n axis-aligned cubes of arbitrary sizes in \({\mathbb R}^3\) in general position. Let \(\mathcal {U}:=\mathcal {U}(\mathcal {C})\) be their union, and let \(\kappa \) be the number of vertices on \(\partial \mathcal {U}\); \(\kappa \) can vary between O(1) and \(\Theta (n^2)\). We present a partition of \(\mathop {\textrm{cl}}({\mathbb R}^3\setminus \mathcal {U})\) into \(O(\kappa \log ^4 n)\) axis-aligned boxes with pairwise-disjoint interiors that can be computed in \(O(n \log ^2 n + \kappa \log ^6 n)\) time if the faces of \(\partial \mathcal {U}\) are pre-computed. We also show that a partition of size \(O(\sigma \log ^4 n + \kappa \log ^2 n)\), where \(\sigma \) is the number of input cubes that appear on \(\partial \mathcal {U}\), can be computed in \(O(n \log ^2 n + \sigma \log ^8 n + \kappa \log ^6 n)\) time if the faces of \(\partial \mathcal {U}\) are pre-computed. The complexity and runtime bounds improve to \(O(n\log n)\) if all cubes in \(\mathcal {C}\) are congruent and the faces of \(\partial \mathcal {U}\) are pre-computed. Finally, we show that if \(\mathcal {C}\) is a set of arbitrary axis-aligned boxes in \({\mathbb R}^3\), then a partition of \(\mathop {\textrm{cl}}({\mathbb R}^3\setminus \mathcal {U})\) into \(O(n^{3/2}+\kappa )\) boxes can be computed in time \(O((n^{3/2}+\kappa )\log n)\), where \(\kappa \) is, as above, the number of vertices in \(\mathcal {U}(\mathcal {C})\), which now can vary between O(1) and \(\Theta (n^3)\).