Computational Geometry-Theory and Applications最新文献

筛选
英文 中文
Bottleneck matching in the plane 飞机上的瓶颈匹配
IF 0.6 4区 计算机科学
Computational Geometry-Theory and Applications Pub Date : 2023-06-01 DOI: 10.1016/j.comgeo.2023.101986
Matthew J. Katz , Micha Sharir
{"title":"Bottleneck matching in the plane","authors":"Matthew J. Katz ,&nbsp;Micha Sharir","doi":"10.1016/j.comgeo.2023.101986","DOIUrl":"https://doi.org/10.1016/j.comgeo.2023.101986","url":null,"abstract":"<div><p><span>We present a randomized algorithm that with high probability finds a bottleneck matching in a set of </span><span><math><mi>n</mi><mo>=</mo><mn>2</mn><mi>ℓ</mi></math></span> points in the plane. The algorithm's running time is <span><math><mi>O</mi><mo>(</mo><msup><mrow><mi>n</mi></mrow><mrow><mi>ω</mi><mo>/</mo><mn>2</mn></mrow></msup><mi>log</mi><mo>⁡</mo><mi>n</mi><mo>)</mo></math></span>, where <span><math><mi>ω</mi><mo>&gt;</mo><mn>2</mn></math></span> is a constant such that any two <span><math><mi>n</mi><mo>×</mo><mi>n</mi></math></span> matrices can be multiplied in time <span><math><mi>O</mi><mo>(</mo><msup><mrow><mi>n</mi></mrow><mrow><mi>ω</mi></mrow></msup><mo>)</mo></math></span>. The state of the art in fast matrix multiplication allows us to set <span><math><mi>ω</mi><mo>=</mo><mn>2.3728596</mn></math></span>.</p></div>","PeriodicalId":51001,"journal":{"name":"Computational Geometry-Theory and Applications","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49795348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
On the geometric priority set cover problem 关于几何优先级集覆盖问题
IF 0.6 4区 计算机科学
Computational Geometry-Theory and Applications Pub Date : 2023-06-01 DOI: 10.1016/j.comgeo.2023.101984
Aritra Banik , Rajiv Raman , Saurabh Ray
{"title":"On the geometric priority set cover problem","authors":"Aritra Banik ,&nbsp;Rajiv Raman ,&nbsp;Saurabh Ray","doi":"10.1016/j.comgeo.2023.101984","DOIUrl":"https://doi.org/10.1016/j.comgeo.2023.101984","url":null,"abstract":"<div><p><span>We study the priority set cover problem for simple geometric set systems in the plane. For pseudo-halfspaces in the plane we obtain a PTAS via local search by showing that the corresponding set system admits a planar support. We show that the problem is APX-hard even for unit disks in the plane and argue that in this case the standard local search algorithm can output a solution that is arbitrarily bad compared to the optimal solution. We then present an LP-relative constant factor </span>approximation algorithm (which also works in the weighted setting) for unit disks via quasi-uniform sampling. As a consequence we obtain a constant factor approximation for the capacitated set cover problem with unit disks. For arbitrary size disks, we show that the problem is at least as hard as the vertex cover problem in general graphs even when the disks have nearly equal sizes. We also present a few simple results for unit squares and orthants in the plane.</p></div>","PeriodicalId":51001,"journal":{"name":"Computational Geometry-Theory and Applications","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49795351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Linear-time approximation scheme for k-means clustering of axis-parallel affine subspaces 轴平行仿射子空间k均值聚类的线性时间近似格式
IF 0.6 4区 计算机科学
Computational Geometry-Theory and Applications Pub Date : 2023-06-01 DOI: 10.1016/j.comgeo.2023.101981
Kyungjin Cho, Eunjin Oh
{"title":"Linear-time approximation scheme for k-means clustering of axis-parallel affine subspaces","authors":"Kyungjin Cho,&nbsp;Eunjin Oh","doi":"10.1016/j.comgeo.2023.101981","DOIUrl":"https://doi.org/10.1016/j.comgeo.2023.101981","url":null,"abstract":"<div><p>In this paper, we present a linear-time approximation scheme for <em>k</em>-means clustering of <em>incomplete</em> data points in <em>d</em>-dimensional Euclidean space. An <em>incomplete</em> data point with <span><math><mi>Δ</mi><mo>&gt;</mo><mn>0</mn></math></span><span><span> unspecified entries is represented as an axis-parallel affine subspace of dimension Δ. The distance between two incomplete data points is defined as the </span>Euclidean distance between two closest points in the axis-parallel affine subspaces corresponding to the data points. We present an algorithm for </span><em>k</em>-means clustering of <em>n</em> axis-parallel affine subspaces of dimension Δ that yields an <span><math><mo>(</mo><mn>1</mn><mo>+</mo><mi>ϵ</mi><mo>)</mo></math></span>-approximate solution in <span><math><mi>O</mi><mo>(</mo><mi>n</mi><mi>d</mi><mo>)</mo></math></span> time. The constants hidden behind <span><math><mi>O</mi><mo>(</mo><mo>⋅</mo><mo>)</mo></math></span> depend only on <span><math><mi>Δ</mi><mo>,</mo><mi>ϵ</mi></math></span> and <em>k</em>. This improves the <span><math><mi>O</mi><mo>(</mo><msup><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msup><mi>d</mi><mo>)</mo></math></span>-time algorithm by Eiben et al. (2021) <span>[7]</span> by a factor of <em>n</em>.</p></div>","PeriodicalId":51001,"journal":{"name":"Computational Geometry-Theory and Applications","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49837673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Colouring bottomless rectangles and arborescences 为无底矩形和树景着色
IF 0.6 4区 计算机科学
Computational Geometry-Theory and Applications Pub Date : 2023-06-01 DOI: 10.1016/j.comgeo.2023.102020
Jean Cardinal , Kolja Knauer , Piotr Micek , Dömötör Pálvölgyi , Torsten Ueckerdt , Narmada Varadarajan
{"title":"Colouring bottomless rectangles and arborescences","authors":"Jean Cardinal ,&nbsp;Kolja Knauer ,&nbsp;Piotr Micek ,&nbsp;Dömötör Pálvölgyi ,&nbsp;Torsten Ueckerdt ,&nbsp;Narmada Varadarajan","doi":"10.1016/j.comgeo.2023.102020","DOIUrl":"https://doi.org/10.1016/j.comgeo.2023.102020","url":null,"abstract":"<div><p>We study problems related to colouring families of bottomless rectangles in the plane, in an attempt to improve the <em>polychromatic k-colouring number</em> <span><math><msubsup><mrow><mi>m</mi></mrow><mrow><mi>k</mi></mrow><mrow><mo>⁎</mo></mrow></msubsup></math></span>. This number is the smallest <em>m</em> such that any collection of bottomless rectangles can be <em>k</em>-coloured so that any <em>m</em>-fold covered point is covered by all <em>k</em> colours. We show that for many families of bottomless rectangles, such as unit-width bottomless rectangles, or bottomless rectangles whose left corners lie on a line, <span><math><msubsup><mrow><mi>m</mi></mrow><mrow><mi>k</mi></mrow><mrow><mo>⁎</mo></mrow></msubsup></math></span> is linear in <em>k</em>. We present the lower bound <span><math><msubsup><mrow><mi>m</mi></mrow><mrow><mi>k</mi></mrow><mrow><mo>⁎</mo></mrow></msubsup><mo>≥</mo><mn>2</mn><mi>k</mi><mo>−</mo><mn>1</mn></math></span> for general families.</p><p>We also investigate <em>semi-online</em> colouring algorithms, which need not colour each vertex immediately, but must maintain a proper colouring. We prove that for many sweeping orders, for any positive integers <span><math><mi>m</mi><mo>,</mo><mi>k</mi></math></span>, there is no semi-online algorithm that can <em>k</em>-colour bottomless rectangles presented in that order, so that any <em>m</em>-fold covered point is covered by at least two colours. This holds even for translates of quadrants, and is a corollary of a stronger result for arborescence colourings: Any semi-online colouring algorithm that colours an arborescence presented in post-order may produce arbitrarily long monochromatic paths.</p></div>","PeriodicalId":51001,"journal":{"name":"Computational Geometry-Theory and Applications","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49791319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 4
Partial matchings induced by morphisms between persistence modules 持久模间态射引起的部分匹配
IF 0.6 4区 计算机科学
Computational Geometry-Theory and Applications Pub Date : 2023-06-01 DOI: 10.1016/j.comgeo.2023.101985
R. Gonzalez-Diaz, M. Soriano-Trigueros, A. Torras-Casas
{"title":"Partial matchings induced by morphisms between persistence modules","authors":"R. Gonzalez-Diaz,&nbsp;M. Soriano-Trigueros,&nbsp;A. Torras-Casas","doi":"10.1016/j.comgeo.2023.101985","DOIUrl":"https://doi.org/10.1016/j.comgeo.2023.101985","url":null,"abstract":"<div><p>We study how to obtain partial matchings using the block function <span><math><msub><mrow><mi>M</mi></mrow><mrow><mi>f</mi></mrow></msub></math></span>, induced by a morphism <em>f</em> between persistence modules. <span><math><msub><mrow><mi>M</mi></mrow><mrow><mi>f</mi></mrow></msub></math></span> is defined algebraically and is linear with respect to direct sums of morphisms. We study some interesting properties of <span><math><msub><mrow><mi>M</mi></mrow><mrow><mi>f</mi></mrow></msub></math></span>, and provide a way of obtaining <span><math><msub><mrow><mi>M</mi></mrow><mrow><mi>f</mi></mrow></msub></math></span> using matrix operations.</p></div>","PeriodicalId":51001,"journal":{"name":"Computational Geometry-Theory and Applications","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49795349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Shortcut hulls: Vertex-restricted outer simplifications of polygons 快捷外壳线:多边形的受顶点限制的外部简化
IF 0.6 4区 计算机科学
Computational Geometry-Theory and Applications Pub Date : 2023-06-01 DOI: 10.1016/j.comgeo.2023.101983
Annika Bonerath , Jan-Henrik Haunert , Joseph S.B. Mitchell , Benjamin Niedermann
{"title":"Shortcut hulls: Vertex-restricted outer simplifications of polygons","authors":"Annika Bonerath ,&nbsp;Jan-Henrik Haunert ,&nbsp;Joseph S.B. Mitchell ,&nbsp;Benjamin Niedermann","doi":"10.1016/j.comgeo.2023.101983","DOIUrl":"https://doi.org/10.1016/j.comgeo.2023.101983","url":null,"abstract":"<div><p>Let <em>P</em> be a polygon and <span><math><mi>C</mi></math></span> a set of shortcuts, where each shortcut is a directed straight-line segment connecting two vertices of <em>P</em>. A shortcut hull of <em>P</em> is another polygon that encloses <em>P</em> and whose oriented boundary is composed of elements from <span><math><mi>C</mi></math></span>. We require <em>P</em><span> and the output shortcut hull to be weakly simple polygons<span>, which we define as a generalization of simple polygons. Shortcut hulls find their application in cartography, where a common task is to compute simplified representations of area features. We aim at a shortcut hull that has a small area and a small perimeter. Our optimization objective is to minimize a convex combination of these two criteria. If no holes in the shortcut hull are allowed, the problem admits a straight-forward solution via computation of shortest paths. For the more challenging case in which the shortcut hull may contain holes, we present a polynomial-time algorithm that is based on computing a constrained, weighted triangulation of the input polygon's exterior. We use this problem as a starting point for investigating further variants, e.g., restricting the number of edges or bends. We demonstrate that shortcut hulls can be used for the schematization of polygons.</span></span></p></div>","PeriodicalId":51001,"journal":{"name":"Computational Geometry-Theory and Applications","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49795346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Rectangle stabbing and orthogonal range reporting lower bounds in moderate dimensions 矩形插入和正交范围报告中等尺寸的下限
IF 0.6 4区 计算机科学
Computational Geometry-Theory and Applications Pub Date : 2023-04-01 DOI: 10.1016/j.comgeo.2022.101959
Peyman Afshani, Rasmus Killmann
{"title":"Rectangle stabbing and orthogonal range reporting lower bounds in moderate dimensions","authors":"Peyman Afshani,&nbsp;Rasmus Killmann","doi":"10.1016/j.comgeo.2022.101959","DOIUrl":"https://doi.org/10.1016/j.comgeo.2022.101959","url":null,"abstract":"<div><p>We study the orthogonal range reporting and rectangle stabbing problems in moderate dimensions, i.e., when the dimension is <span><math><mi>c</mi><mi>log</mi><mo>⁡</mo><mo>(</mo><mi>n</mi><mo>)</mo></math></span> for some constant <em>c</em>. In orthogonal range reporting, the input is a set of <em>n</em> points in <em>d</em> dimensions, and the goal is to store these <em>n</em><span> points in a data structure such that given a query rectangle, we can report all the input points contained in the rectangle. The rectangle stabbing problem is the “dual” problem where the input is a set of rectangles, and the query is a point.</span></p><p>Our main result is the following: assume using <span><math><mi>S</mi><mo>(</mo><mi>n</mi><mo>)</mo></math></span> space, we can solve either problem in <span><math><mi>d</mi><mo>=</mo><mi>c</mi><mi>log</mi><mo>⁡</mo><mi>n</mi></math></span> dimensions, <span><math><mi>c</mi><mo>≥</mo><mn>4</mn></math></span>, using <span><math><mi>Q</mi><mo>(</mo><mi>n</mi><mo>)</mo><mo>+</mo><mi>O</mi><mo>(</mo><mi>t</mi><mo>)</mo></math></span><span> time in the pointer machine model of computation where </span><em>t</em> is the output size. Then, we show that if the query time is small, that is, <span><math><mi>Q</mi><mo>(</mo><mi>n</mi><mo>)</mo><mo>=</mo><msup><mrow><mi>n</mi></mrow><mrow><mn>1</mn><mo>−</mo><mi>γ</mi></mrow></msup></math></span>, for <span><math><mi>γ</mi><mo>≥</mo><mfrac><mrow><mn>2</mn></mrow><mrow><mn>2</mn><mo>+</mo><mi>log</mi><mo>⁡</mo><mi>c</mi></mrow></mfrac></math></span>, then the space must be <span><math><mi>Ω</mi><mrow><mo>(</mo><msup><mrow><mi>n</mi></mrow><mrow><mn>1</mn><mo>−</mo><mi>γ</mi></mrow></msup><msup><mrow><mi>n</mi></mrow><mrow><msqrt><mrow><mi>c</mi><mi>γ</mi></mrow></msqrt><mo>/</mo><mi>e</mi><mo>−</mo><mi>o</mi><mo>(</mo><msqrt><mrow><mi>c</mi><mi>γ</mi></mrow></msqrt><mo>)</mo></mrow></msup><mo>)</mo></mrow></math></span><span>. Interestingly, we obtain this lower bound using a non-constructive method, and we show the existence of some codes that generalize a specific aspect of error correction codes. Our result overcomes the shortcomings of the previous lower bounds in the pointer machine model for non-constant dimension </span><span>[3]</span>, <span>[4]</span>, <span>[5]</span>, <span>[13]</span>, as the previous results could not be extended for <span><math><mi>d</mi><mo>=</mo><mi>Ω</mi><mo>(</mo><msqrt><mrow><mi>log</mi><mo>⁡</mo><mi>n</mi></mrow></msqrt><mo>)</mo></math></span>.</p><p>The only known lower bounds for rectangle stabbing, when the dimension is non-constant, are based on conditional lower bounds upon the best-known results on CNF-SAT <span>[21]</span>. Therefore, our lower bound is the first non-trivial unconditional lower bound for orthogonal range reporting and rectangle stabbing with non-constant dimension.</p></div>","PeriodicalId":51001,"journal":{"name":"Computational Geometry-Theory and Applications","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49851373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Unfoldings and nets of regular polytopes 正则多面体的展开与网
IF 0.6 4区 计算机科学
Computational Geometry-Theory and Applications Pub Date : 2023-04-01 DOI: 10.1016/j.comgeo.2022.101977
Satyan L. Devadoss , Matthew Harvey
{"title":"Unfoldings and nets of regular polytopes","authors":"Satyan L. Devadoss ,&nbsp;Matthew Harvey","doi":"10.1016/j.comgeo.2022.101977","DOIUrl":"https://doi.org/10.1016/j.comgeo.2022.101977","url":null,"abstract":"<div><p><span>Over a decade ago, it was shown that every edge unfolding of the Platonic solids<span> was without self-overlap, yielding a valid net. We consider this property for their higher-dimensional analogs, the regular polytopes. Three classes of regular polytopes exist for all dimensions (</span></span><em>n</em>-simplex, <em>n</em>-cube, <em>n</em>-orthoplex) and three additional regular polytopes appear only in four-dimensions (24-cell, 120-cell, 600-cell). It was recently proven that all unfoldings of the <em>n</em>-cube yield nets. We extend this to the <em>n</em><span><span>-simplex and the 4-orthoplex using the geometry of simplicial chains. Finally, we demonstrate failure of this property for any orthoplex of higher dimension, as well as for the 600-cell, providing </span>counterexamples. We conjecture failure for the two remaining open cases, the 24-cell and the 120-cell.</span></p></div>","PeriodicalId":51001,"journal":{"name":"Computational Geometry-Theory and Applications","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49810277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Untangling circular drawings: Algorithms and complexity 解开圆形图形的角度:算法和复杂性
IF 0.6 4区 计算机科学
Computational Geometry-Theory and Applications Pub Date : 2023-04-01 DOI: 10.1016/j.comgeo.2022.101975
Sujoy Bhore , Guangping Li , Martin Nöllenburg , Ignaz Rutter , Hsiang-Yun Wu
{"title":"Untangling circular drawings: Algorithms and complexity","authors":"Sujoy Bhore ,&nbsp;Guangping Li ,&nbsp;Martin Nöllenburg ,&nbsp;Ignaz Rutter ,&nbsp;Hsiang-Yun Wu","doi":"10.1016/j.comgeo.2022.101975","DOIUrl":"https://doi.org/10.1016/j.comgeo.2022.101975","url":null,"abstract":"<div><p>We consider the problem of untangling a given (non-planar) straight-line circular drawing <span><math><msub><mrow><mi>δ</mi></mrow><mrow><mi>G</mi></mrow></msub></math></span> of an outerplanar graph <span><math><mi>G</mi><mo>=</mo><mo>(</mo><mi>V</mi><mo>,</mo><mi>E</mi><mo>)</mo></math></span> into a planar straight-line circular drawing of <em>G</em> by shifting a minimum number of vertices to a new position on the circle. For an outerplanar graph <em>G</em>, it is obvious that such a crossing-free circular drawing always exists and we define the <em>circular shifting number</em> <span><math><msup><mrow><mi>shift</mi></mrow><mrow><mo>∘</mo></mrow></msup><mo>(</mo><msub><mrow><mi>δ</mi></mrow><mrow><mi>G</mi></mrow></msub><mo>)</mo></math></span> as the minimum number of vertices that are required to be shifted in order to resolve all crossings of <span><math><msub><mrow><mi>δ</mi></mrow><mrow><mi>G</mi></mrow></msub></math></span>. We show that the problem <span>Circular Untangling</span>, asking whether <span><math><msup><mrow><mi>shift</mi></mrow><mrow><mo>∘</mo></mrow></msup><mo>(</mo><msub><mrow><mi>δ</mi></mrow><mrow><mi>G</mi></mrow></msub><mo>)</mo><mo>≤</mo><mi>K</mi></math></span> for a given integer <em>K</em>, is <span>NP</span>-complete. For <em>n</em>-vertex outerplanar graphs, we obtain a tight upper bound of <span><math><msup><mrow><mi>shift</mi></mrow><mrow><mo>∘</mo></mrow></msup><mo>(</mo><msub><mrow><mi>δ</mi></mrow><mrow><mi>G</mi></mrow></msub><mo>)</mo><mo>≤</mo><mi>n</mi><mo>−</mo><mo>⌊</mo><msqrt><mrow><mi>n</mi><mo>−</mo><mn>2</mn></mrow></msqrt><mo>⌋</mo><mo>−</mo><mn>2</mn></math></span>. Moreover, we study the <span>Circular Untangling</span> for <em>almost-planar</em> circular drawings, in which a single edge is involved in all of the crossings. For this problem, we provide a tight upper bound <span><math><msup><mrow><mi>shift</mi></mrow><mrow><mo>∘</mo></mrow></msup><mo>(</mo><msub><mrow><mi>δ</mi></mrow><mrow><mi>G</mi></mrow></msub><mo>)</mo><mo>≤</mo><mo>⌊</mo><mfrac><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></mfrac><mo>⌋</mo><mo>−</mo><mn>1</mn></math></span> and present an <span><math><mi>O</mi><mo>(</mo><msup><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>)</mo></math></span>-time algorithm to compute the circular shifting number of almost-planar drawings.</p></div>","PeriodicalId":51001,"journal":{"name":"Computational Geometry-Theory and Applications","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49851374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
How close is a quad mesh to a polycube? 四边形网格与多边形网格的距离有多近?
IF 0.6 4区 计算机科学
Computational Geometry-Theory and Applications Pub Date : 2023-04-01 DOI: 10.1016/j.comgeo.2022.101978
Markus Baumeister, Leif Kobbelt
{"title":"How close is a quad mesh to a polycube?","authors":"Markus Baumeister,&nbsp;Leif Kobbelt","doi":"10.1016/j.comgeo.2022.101978","DOIUrl":"https://doi.org/10.1016/j.comgeo.2022.101978","url":null,"abstract":"<div><p>We compute the shortest sequence of local connectivity modifications that transform a genus 0 quad mesh to a polycube. The modification operations are (dual) loop preserving and thus, we are restricted to quad meshes where loops don't self-intersect and two loops intersect at most twice. The intersection patterns of the loops are encoded in a simplicial complex, which we call loop complex. To formulate the modification search over the loop complex, we characterise polycubes combinatorially and determine dependencies between modifications. We show that the full task can be encoded as a mixed-integer problem that is solved by a commodity MIP-solver. We demonstrate the practical feasibility by a number of examples with varying complexity.</p></div>","PeriodicalId":51001,"journal":{"name":"Computational Geometry-Theory and Applications","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49810278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
0
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
相关产品
×
本文献相关产品
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信