{"title":"从稀疏图构建大型k核","authors":"Fedor V. Fomin , Danil Sagunov , Kirill Simonov","doi":"10.1016/j.jcss.2022.10.002","DOIUrl":null,"url":null,"abstract":"<div><p>A <em>k</em>-core of a graph <em>G</em> is the maximal induced subgraph in which every vertex has degree at least <em>k</em>. In the <span>Edge</span> <em>k</em><span>-Core</span> optimization problem, we are given a graph <em>G</em> and integers <em>k</em>, <em>b</em> and <em>p</em>. The task is to ensure that the <em>k</em>-core of <em>G</em> has at least <em>p</em> vertices, by adding at most <em>b</em> edges. While <span>Edge</span> <em>k</em><span>-Core</span> is known to be computationally hard in general, we show that there are efficient algorithms when the <em>k</em>-core has to be constructed from a sparse graph with some structural properties. Our results are as follows.</p><ul><li><span>•</span><span><p>When the input graph is a forest, <span>Edge</span> <em>k</em><span>-Core</span> is solvable in polynomial time.</p></span></li><li><span>•</span><span><p><span>Edge</span> <em>k</em><span>-Core</span> is fixed-parameter tractable (FPT) when parameterized by the minimum size of a vertex cover in the input graph.</p></span></li><li><span>•</span><span><p><span>Edge</span> <em>k</em><span>-Core</span> is <span><math><mi>FPT</mi></math></span> when parameterized by the treewidth of the graph plus <em>k</em>.</p></span></li></ul></div>","PeriodicalId":50224,"journal":{"name":"Journal of Computer and System Sciences","volume":"132 ","pages":"Pages 68-88"},"PeriodicalIF":1.1000,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Building large k-cores from sparse graphs\",\"authors\":\"Fedor V. Fomin , Danil Sagunov , Kirill Simonov\",\"doi\":\"10.1016/j.jcss.2022.10.002\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>A <em>k</em>-core of a graph <em>G</em> is the maximal induced subgraph in which every vertex has degree at least <em>k</em>. In the <span>Edge</span> <em>k</em><span>-Core</span> optimization problem, we are given a graph <em>G</em> and integers <em>k</em>, <em>b</em> and <em>p</em>. The task is to ensure that the <em>k</em>-core of <em>G</em> has at least <em>p</em> vertices, by adding at most <em>b</em> edges. While <span>Edge</span> <em>k</em><span>-Core</span> is known to be computationally hard in general, we show that there are efficient algorithms when the <em>k</em>-core has to be constructed from a sparse graph with some structural properties. Our results are as follows.</p><ul><li><span>•</span><span><p>When the input graph is a forest, <span>Edge</span> <em>k</em><span>-Core</span> is solvable in polynomial time.</p></span></li><li><span>•</span><span><p><span>Edge</span> <em>k</em><span>-Core</span> is fixed-parameter tractable (FPT) when parameterized by the minimum size of a vertex cover in the input graph.</p></span></li><li><span>•</span><span><p><span>Edge</span> <em>k</em><span>-Core</span> is <span><math><mi>FPT</mi></math></span> when parameterized by the treewidth of the graph plus <em>k</em>.</p></span></li></ul></div>\",\"PeriodicalId\":50224,\"journal\":{\"name\":\"Journal of Computer and System Sciences\",\"volume\":\"132 \",\"pages\":\"Pages 68-88\"},\"PeriodicalIF\":1.1000,\"publicationDate\":\"2023-03-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Computer and System Sciences\",\"FirstCategoryId\":\"94\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0022000022000721\",\"RegionNum\":3,\"RegionCategory\":\"计算机科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"BUSINESS, FINANCE\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Computer and System Sciences","FirstCategoryId":"94","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0022000022000721","RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"BUSINESS, FINANCE","Score":null,"Total":0}
A k-core of a graph G is the maximal induced subgraph in which every vertex has degree at least k. In the Edgek-Core optimization problem, we are given a graph G and integers k, b and p. The task is to ensure that the k-core of G has at least p vertices, by adding at most b edges. While Edgek-Core is known to be computationally hard in general, we show that there are efficient algorithms when the k-core has to be constructed from a sparse graph with some structural properties. Our results are as follows.
•
When the input graph is a forest, Edgek-Core is solvable in polynomial time.
•
Edgek-Core is fixed-parameter tractable (FPT) when parameterized by the minimum size of a vertex cover in the input graph.
•
Edgek-Core is when parameterized by the treewidth of the graph plus k.
期刊介绍:
The Journal of Computer and System Sciences publishes original research papers in computer science and related subjects in system science, with attention to the relevant mathematical theory. Applications-oriented papers may also be accepted and they are expected to contain deep analytic evaluation of the proposed solutions.
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