Journal of Computer and System Sciences最新文献

A linear delay algorithm in SD set system and its application to subgraph enumeration

IF 1.1 3区计算机科学

Journal of Computer and System Sciences Pub Date : 2025-02-21 DOI: 10.1016/j.jcss.2025.103637

Takumi Tada, Kazuya Haraguchi

{"title":"A linear delay algorithm in SD set system and its application to subgraph enumeration","authors":"Takumi Tada, Kazuya Haraguchi","doi":"10.1016/j.jcss.2025.103637","DOIUrl":"10.1016/j.jcss.2025.103637","url":null,"abstract":"<div><div>For a set system <span><math><mo>(</mo><mi>V</mi><mo>,</mo><mi>C</mi><mo>⊆</mo><msup><mrow><mn>2</mn></mrow><mrow><mi>V</mi></mrow></msup><mo>)</mo></math></span>, we call each <span><math><mi>C</mi><mo>∈</mo><mi>C</mi></math></span> a component. A nonempty subset <span><math><mi>Y</mi><mo>⊊</mo><mi>C</mi></math></span> is a removable set (RS) of <em>C</em> if <span><math><mi>C</mi><mo>∖</mo><mi>Y</mi></math></span> is a component. We say that a set system has subset-disjoint (SD) property if, for any two components <span><math><mi>C</mi><mo>,</mo><msup><mrow><mi>C</mi></mrow><mrow><mo>′</mo></mrow></msup></math></span> with <span><math><msup><mrow><mi>C</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>⊊</mo><mi>C</mi></math></span>, every minimal RS <em>Y</em> of <em>C</em> satisfies either <span><math><mi>Y</mi><mo>⊆</mo><msup><mrow><mi>C</mi></mrow><mrow><mo>′</mo></mrow></msup></math></span> or <span><math><mi>Y</mi><mo>∩</mo><msup><mrow><mi>C</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>=</mo><mo>∅</mo></math></span>. Assuming that an SD set system is implicitly given by an oracle that returns a minimal RS of a component, we provide an algorithm that enumerates all components in linear time/space with respect to <span><math><mo>|</mo><mi>V</mi><mo>|</mo></math></span> and oracle running time/space. We then extend this algorithm to linear-delay enumeration of all 2-edge-connected (or 2-vertex-connected) induced subgraphs in an undirected graph and of all strongly connected subgraphs in a digraph.</div></div>","PeriodicalId":50224,"journal":{"name":"Journal of Computer and System Sciences","volume":"152 ","pages":"Article 103637"},"PeriodicalIF":1.1,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143509232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Induced tree covering and the generalized Yutsis property

IF 1.1 3区计算机科学

Journal of Computer and System Sciences Pub Date : 2025-02-13 DOI: 10.1016/j.jcss.2025.103636

Luís Cunha , Gabriel Duarte , Fábio Protti , Loana Nogueira , Uéverton Souza

引用次数: 0

Destroying densest subgraphs is hard

IF 1.1 3区计算机科学

Journal of Computer and System Sciences Pub Date : 2025-02-13 DOI: 10.1016/j.jcss.2025.103635

Cristina Bazgan , André Nichterlein , Sofia Vazquez Alferez

{"title":"Destroying densest subgraphs is hard","authors":"Cristina Bazgan , André Nichterlein , Sofia Vazquez Alferez","doi":"10.1016/j.jcss.2025.103635","DOIUrl":"10.1016/j.jcss.2025.103635","url":null,"abstract":"<div><div>We analyze the computational complexity of the following computational problems called <span>Bounded-Density Edge Deletion</span> and <span>Bounded-Density Vertex Deletion</span>: Given a graph <em>G</em>, a budget <em>k</em> and a target density <span><math><msub><mrow><mi>τ</mi></mrow><mrow><mi>ρ</mi></mrow></msub></math></span>, are there <em>k</em> edges (<em>k</em> vertices) whose removal from <em>G</em> results in a graph where the densest subgraph has density at most <span><math><msub><mrow><mi>τ</mi></mrow><mrow><mi>ρ</mi></mrow></msub></math></span>? Here, the density of a graph is the number of its edges divided by the number of its vertices. We prove that both problems are polynomial-time solvable on trees and cliques but are NP-complete on planar bipartite graphs and split graphs. From a parameterized point of view, we show that both problems are fixed-parameter tractable with respect to the vertex cover number but W[1]-hard with respect to the solution size. Furthermore, we prove that <span>Bounded-Density Edge Deletion</span> is W[1]-hard with respect to the feedback edge number, demonstrating that the problem remains hard on very sparse graphs.</div></div>","PeriodicalId":50224,"journal":{"name":"Journal of Computer and System Sciences","volume":"151 ","pages":"Article 103635"},"PeriodicalIF":1.1,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143444148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Languages given by finite automata over the unary alphabet

IF 1.1 3区计算机科学

Journal of Computer and System Sciences Pub Date : 2025-02-05 DOI: 10.1016/j.jcss.2025.103634

Wojciech Czerwiński , Maciej Dębski , Tomasz Gogasz , Gordon Hoi , Sanjay Jain , Michał Skrzypczak , Frank Stephan , Christopher Tan

{"title":"Languages given by finite automata over the unary alphabet","authors":"Wojciech Czerwiński , Maciej Dębski , Tomasz Gogasz , Gordon Hoi , Sanjay Jain , Michał Skrzypczak , Frank Stephan , Christopher Tan","doi":"10.1016/j.jcss.2025.103634","DOIUrl":"10.1016/j.jcss.2025.103634","url":null,"abstract":"<div><div>This paper studies the complexity of operations on finite automata and the complexity of their decision problems when the alphabet is unary. Let <em>n</em> denote the number of states of the input automata considered. The following main results are obtained:</div><div>(1) Equality and inclusion of NFAs can be decided within time <span><math><msup><mrow><mn>2</mn></mrow><mrow><mi>O</mi><mo>(</mo><msup><mrow><mo>(</mo><mi>n</mi><mi>log</mi><mo>⁡</mo><mi>n</mi><mo>)</mo></mrow><mrow><mn>1</mn><mo>/</mo><mn>3</mn></mrow></msup><mo>)</mo></mrow></msup></math></span>. The previous upper bound <span><math><msup><mrow><mn>2</mn></mrow><mrow><mi>O</mi><mo>(</mo><msup><mrow><mo>(</mo><mi>n</mi><mi>log</mi><mo>⁡</mo><mi>n</mi><mo>)</mo></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msup><mo>)</mo></mrow></msup></math></span> was by Chrobak (1986).</div><div>(2) One can determine a UFA (unambiguous finite automata) for complement of another UFA or union of two UFAs using at most quasipolynomial number of states. However, for concatenation of two <em>n</em>-state UFAs, the worst case is a UFA having <span><math><msup><mrow><mn>2</mn></mrow><mrow><mi>Θ</mi><mo>(</mo><msup><mrow><mo>(</mo><mi>n</mi><msup><mrow><mi>log</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>⁡</mo><mi>n</mi><mo>)</mo></mrow><mrow><mn>1</mn><mo>/</mo><mn>3</mn></mrow></msup><mo>)</mo></mrow></msup></math></span> states.</div><div>(3) Results when an infinite <em>ω</em>-word given by a UFA or an NFA is a member of a given regular <em>ω</em>-language are obtained.</div></div>","PeriodicalId":50224,"journal":{"name":"Journal of Computer and System Sciences","volume":"151 ","pages":"Article 103634"},"PeriodicalIF":1.1,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Dominator coloring and CD coloring in almost cluster graphs

IF 1.1 3区计算机科学

Journal of Computer and System Sciences Pub Date : 2025-02-04 DOI: 10.1016/j.jcss.2025.103633

Aritra Banik , Prahlad Narasimhan Kasthurirangan , Venkatesh Raman

{"title":"Dominator coloring and CD coloring in almost cluster graphs","authors":"Aritra Banik , Prahlad Narasimhan Kasthurirangan , Venkatesh Raman","doi":"10.1016/j.jcss.2025.103633","DOIUrl":"10.1016/j.jcss.2025.103633","url":null,"abstract":"<div><div>In this paper, we study two variants of Coloring - <span>Dominator Coloring</span> and <span>Class Domination Coloring</span>. In both problems, we are given a graph <em>G</em> and a <span><math><mi>ℓ</mi><mo>∈</mo><mi>N</mi></math></span> and the goal is to properly color the vertices with at most <em>ℓ</em> colors. In <span>Dominator Coloring</span>, we require for each <span><math><mi>v</mi><mo>∈</mo><mi>V</mi><mo>(</mo><mi>G</mi><mo>)</mo></math></span>, a color <em>c</em> such that <em>v</em> dominates all vertices colored <em>c</em>. In <span>Class Domination Coloring</span>, we require for each color <em>c</em>, a <span><math><mi>v</mi><mo>∈</mo><mi>V</mi><mo>(</mo><mi>G</mi><mo>)</mo></math></span> which dominates all vertices colored <em>c</em>. We prove that <span>Dominator Coloring</span> is <span>FPT</span> when parameterized by the size of a graph's CVD set and that <span>Class Domination Coloring</span> is <span>FPT</span> parameterized by CVD set size plus the number of remaining cliques. En route, we design simpler algorithms when the problems are parameterized by the size of a graph's twin cover. When the parameter is the size of a graph's clique modulator, we design a randomized single-exponential time algorithm.</div></div>","PeriodicalId":50224,"journal":{"name":"Journal of Computer and System Sciences","volume":"150 ","pages":"Article 103633"},"PeriodicalIF":1.1,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143395174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Parameterized complexity of dominating set variants in almost cluster and split graphs

IF 1.1 3区计算机科学

Journal of Computer and System Sciences Pub Date : 2025-02-03 DOI: 10.1016/j.jcss.2025.103631

Dishant Goyal , Ashwin Jacob , Kaushtubh Kumar , Diptapriyo Majumdar , Venkatesh Raman

{"title":"Parameterized complexity of dominating set variants in almost cluster and split graphs","authors":"Dishant Goyal , Ashwin Jacob , Kaushtubh Kumar , Diptapriyo Majumdar , Venkatesh Raman","doi":"10.1016/j.jcss.2025.103631","DOIUrl":"10.1016/j.jcss.2025.103631","url":null,"abstract":"<div><div>We consider structural parameterizations of several variants of <span>Dominating Set</span> in the parameter ecology program. We give improved FPT algorithms and lower bounds under well-known conjectures for <span>Dominating Set</span> and its variants in graphs that are <em>k</em> vertices away from a cluster graph or a split graph. These are graphs in which there is a set of <em>k</em> vertices (called the modulator) whose deletion results in a cluster graph or a split graph. We also call <em>k</em> as the deletion distance (to the appropriate class of graphs). For example, we show that when parameterized by the deletion distance <em>k</em> to cluster graphs: <span>Dominating Set</span>, <span>Independent Dominating Set</span>, <span>Dominating Clique</span>, <span>Efficient Dominating Set</span> and <span>Total Dominating Set</span> can be solved in <span><math><msup><mrow><mn>3</mn></mrow><mrow><mi>k</mi></mrow></msup><msup><mrow><mi>n</mi></mrow><mrow><mi>O</mi><mo>(</mo><mn>1</mn><mo>)</mo></mrow></msup></math></span>-time. Additionally, when parameterized by the deletion distance <em>k</em> to split graphs, we prove that <span>Efficient Dominating Set</span> can be solved in <span><math><msup><mrow><mn>3</mn></mrow><mrow><mi>k</mi><mo>/</mo><mn>2</mn></mrow></msup><msup><mrow><mi>n</mi></mrow><mrow><mi>O</mi><mo>(</mo><mn>1</mn><mo>)</mo></mrow></msup></math></span>-time breaking the <span><math><msup><mrow><mn>2</mn></mrow><mrow><mi>k</mi></mrow></msup></math></span> barrier.</div></div>","PeriodicalId":50224,"journal":{"name":"Journal of Computer and System Sciences","volume":"150 ","pages":"Article 103631"},"PeriodicalIF":1.1,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143386924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 similar are two elections?

IF 1.1 3区计算机科学

Journal of Computer and System Sciences Pub Date : 2025-02-03 DOI: 10.1016/j.jcss.2025.103632

Piotr Faliszewski , Piotr Skowron , Arkadii Slinko , Krzysztof Sornat , Stanisław Szufa , Nimrod Talmon

引用次数: 0

The complexity of transitively orienting temporal graphs

IF 1.1 3区计算机科学

Journal of Computer and System Sciences Pub Date : 2025-02-03 DOI: 10.1016/j.jcss.2025.103630

George B. Mertzios , Hendrik Molter , Malte Renken , Paul G. Spirakis , Philipp Zschoche

{"title":"The complexity of transitively orienting temporal graphs","authors":"George B. Mertzios , Hendrik Molter , Malte Renken , Paul G. Spirakis , Philipp Zschoche","doi":"10.1016/j.jcss.2025.103630","DOIUrl":"10.1016/j.jcss.2025.103630","url":null,"abstract":"<div><div>In a temporal network with discrete time-labels on its edges, information can only “flow” along sequences of edges with non-decreasing (resp. increasing) time-labels. In this paper we make a first attempt to understand how the direction of information flow on one edge can impact the direction of information flow on other edges. By naturally extending the classical notion of a transitive orientation in static graphs, we introduce the fundamental notion of a temporal transitive orientation, and we systematically investigate its algorithmic behavior. Our main result is a conceptually simple, yet technically quite involved, polynomial-time algorithm for recognizing whether a temporal graph <span><math><mi>G</mi></math></span> is transitively orientable. In wide contrast we prove that, surprisingly, it is NP-hard to recognize whether <span><math><mi>G</mi></math></span> is strictly transitively orientable. Additionally we introduce further related problems to temporal transitivity, notably among them the temporal transitive completion problem, for which we prove both algorithmic and hardness results.</div></div>","PeriodicalId":50224,"journal":{"name":"Journal of Computer and System Sciences","volume":"150 ","pages":"Article 103630"},"PeriodicalIF":1.1,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143377232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Dense graph partitioning on sparse and dense graphs 稀疏图和密集图上的密集图分割

IF 1.1 3区计算机科学

Journal of Computer and System Sciences Pub Date : 2025-01-21 DOI: 10.1016/j.jcss.2025.103619

Cristina Bazgan , Katrin Casel , Pierre Cazals

引用次数: 0

Forbidden patterns in temporal graphs resulting from encounters in a corridor

IF 1.1 3区计算机科学

Journal of Computer and System Sciences Pub Date : 2025-01-17 DOI: 10.1016/j.jcss.2025.103620

Mónika Csikós , Michel Habib , Minh-Hang Nguyen , Mikaël Rabie , Laurent Viennot

引用次数: 0