{"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":50574,"journal":{"name":"Discrete & Computational Geometry","volume":"175 1","pages":""},"PeriodicalIF":0.6000,"publicationDate":"2024-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Discrete & Computational Geometry","FirstCategoryId":"100","ListUrlMain":"https://doi.org/10.1007/s00454-024-00632-2","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"COMPUTER SCIENCE, THEORY & METHODS","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 \(\Theta (n^3)\).
期刊介绍:
Discrete & Computational Geometry (DCG) is an international journal of mathematics and computer science, covering a broad range of topics in which geometry plays a fundamental role. It publishes papers on such topics as configurations and arrangements, spatial subdivision, packing, covering, and tiling, geometric complexity, polytopes, point location, geometric probability, geometric range searching, combinatorial and computational topology, probabilistic techniques in computational geometry, geometric graphs, geometry of numbers, and motion planning.