{"type":"ScholarlyArticle","title":"Minimizing Reachability Times on Temporal Graphs via Shifting Labels","authors":[{"name":"Argyrios Deligkas","slug":"argyrios-deligkas","given":"Argyrios","family":"Deligkas","affiliation":"Royal Holloway , University of London"},{"name":"Eduard Eiben","slug":"eduard-eiben","given":"Eduard","family":"Eiben","affiliation":"Royal Holloway , University of London"},{"name":"George Skretas","slug":"george-skretas","given":"George","family":"Skretas","affiliation":"Hasso Plattner Institute , University of Potsdam"}],"abstract":"We study how we can accelerate the spreading of information in temporal graphs via shifting operations; a problem that captures real-world applications varying from information flows to distribution schedules. In a temporal graph there is a set of fixed vertices and the available connections between them change over time in a predefined manner.  We observe that, in some cases, shifting some connections, i.e., advancing or delaying them, can decrease the time required to reach from some vertex (source) to another vertex. We study how we can minimize the maximum time a set of sources needs to reach every vertex, when we are allowed to shift some of the connections. If we restrict the allowed number of changes, we prove that, already for a single source, the problem is NP-hard, and W[2]-hard when parameterized by the number of changes. Then we focus on unconstrained number of changes. We derive a polynomial-time algorithm when there is one source. When there are two sources, we show that the problem becomes NP-hard; on the other hand, we design an FPT algorithm parameterized by the treewidth of the graph plus the lifetime of the optimal solution, that works for any number of sources. Finally, we provide polynomial-time algorithms for several graph classes.","doi":"10.24963/ijcai.2023/592","url":"https://ijcai.org/proceedings/2023/592","pdf":"https://ijcai.org/proceedings/2023/0592.pdf","markdown":"https://ijcai.org/proceedings/2023/592.md","bibtex":"https://ijcai.org/proceedings/2023/bibtex/592","volume":{"slug":"2023","title":"Proceedings of the Thirty-Second International Joint Conference on Artificial Intelligence","short_title":"IJCAI 2023","url":"https://ijcai.org/proceedings/2023/","year":2023,"location":"Macao, SAR","dates":"19-25 August 2023","editors":"Edith Elkind","isbn":"978-1-956792-03-4","publisher":"International Joint Conferences on Artificial Intelligence Organization","doi_prefix":"10.24963/ijcai.2023"},"section":"Planning and Scheduling","track":"Main Track","number":592,"pages":{"first":5333,"last":5340},"keywords":["Agent-based and Multi-agent Systems: MAS: Multi-agent planning","Planning and Scheduling: PS: Scheduling","Planning and Scheduling: PS: Theoretical foundations of planning"],"videos":[],"references":[{"position":1,"raw":"[Arnborg et al., 1991] Stefan Arnborg, Jens Lagergren, and Detlef Seese. Easy problems for tree-decomposable graphs. J. Algorithms, 12(2):308-340, 1991.","title":"Easy problems for tree-decomposable graphs","authors":"Stefan Arnborg, Jens Lagergren, Detlef Seese","year":"1991","venue":"J. Algorithms","doi":null,"url":null,"internal_url":null},{"position":2,"raw":"[Braunstein and Ingrosso, 2016] Alfredo Braunstein and Alessandro Ingrosso. Inference of causality in epidemics on temporal contact networks. Scientific reports, 6:27538, 2016.","title":"Inference of causality in epidemics on temporal contact networks","authors":"Ingrosso Braunstein, Alfredo Braunstein, Alessandro Ingrosso","year":"2016","venue":"Scientific reports","doi":null,"url":null,"internal_url":null},{"position":3,"raw":"[Casteigts et al., 2021] Arnaud Casteigts, Anne-Sophie Himmel, Hendrik Molter, and Philipp Zschoche. Find- ing temporal paths under waiting time constraints. Algorithmica, pages 1-49, 2021.","title":"Finding temporal paths under waiting time constraints","authors":"Arnaud Casteigts, Anne-Sophie Himmel, Hendrik Molter, Philipp Zschoche","year":"2021","venue":"Algorithmica","doi":null,"url":null,"internal_url":null},{"position":4,"raw":"[Cygan et al., 2015] Marek Cygan, Fedor V. Fomin, Lukasz Kowalik, Daniel Lokshtanov, Dániel Marx, Marcin Pilipczuk, Michal Pilipczuk, and Saket Saurabh. Parame- terized Algorithms. Springer, 2015. [Darmann and Döcker, 2020] Andreas Darmann and Janosch Döcker. On a simple hard variant of not-all-equal 3-sat. Theoretical Computer Science, 815:147-152, 2020.","title":"Darmann and Döcker, 2020] Andreas Darmann and Janosch Döcker","authors":"Marek Cygan, V Fedor, Lukasz Fomin, Daniel Kowalik, Dániel Lokshtanov, Marcin Marx, Michal Pilipczuk, Saket Pilipczuk, Saurabh","year":"2015","venue":"Theoretical Computer Science","doi":null,"url":null,"internal_url":null},{"position":5,"raw":"[Deligkas and Potapov, 2020] Argyrios Deligkas and Igor Potapov. Optimizing reachability sets in temporal graphs by delaying. In Proc. of AAAI, pages 9810-9817, 2020.","title":"Argyrios Deligkas and Igor Potapov. Optimizing reachability sets in temporal graphs by delaying","authors":"Potapov Deligkas","year":"2020","venue":"Proc. of AAAI","doi":null,"url":null,"internal_url":null},{"position":6,"raw":"[Downey and Fellows, 2013] Rodney G. Downey and Michael R. Fellows. Fundamentals of parameterized complexity. Texts in Computer Science. Springer, 2013.","title":"Fundamentals of parameterized complexity","authors":"Rodney G Downey, Michael R Fellows","year":"2013","venue":"Texts in Computer Science","doi":null,"url":null,"internal_url":null},{"position":7,"raw":"[Enright and Kao, 2018] Jessica Enright and Rowland Ray- mond Kao. Epidemics on dynamic networks. Epidemics, 24:88 -97, 2018.","title":"Epidemics on dynamic networks","authors":"Kao ; Enright, Rowland Raymond Enright, Kao","year":"2018","venue":"Epidemics","doi":null,"url":null,"internal_url":null},{"position":8,"raw":"[Enright and Meeks, 2018] Jessica Enright and Kitty Meeks. Deleting edges to restrict the size of an epidemic: a new application for treewidth. Algorithmica, 80(6):1857-1889, 2018.","title":"Deleting edges to restrict the size of an epidemic: a new application for treewidth","authors":"Meeks Enright, Jessica Enright, Kitty Meeks","year":"2018","venue":"Algorithmica","doi":null,"url":null,"internal_url":null},{"position":9,"raw":"[Enright et al., 2021a] Jessica A. Enright, Kitty Meeks, George B. Mertzios, and Viktor Zamaraev. Deleting edges to restrict the size of an epidemic in temporal networks. J. Comput. Syst. Sci., 119:60-77, 2021.","title":"Deleting edges to restrict the size of an epidemic in temporal networks","authors":"Enright","year":"2021","venue":"J. Comput. Syst. Sci","doi":null,"url":null,"internal_url":null},{"position":10,"raw":"[Enright et al., 2021b] Jessica A. Enright, Kitty Meeks, and Fiona Skerman. Assigning times to minimise reachability in temporal graphs. J. Comput. Syst. Sci., 115:169-186, 2021.","title":"Assigning times to minimise reachability in temporal graphs","authors":"Enright","year":"2021","venue":"J. Comput. Syst. Sci","doi":null,"url":null,"internal_url":null},{"position":11,"raw":"[Kempe et al., 2002] David Kempe, Jon Kleinberg, and Amit Kumar. Connectivity and inference problems for temporal networks. Journal of Computer and System Sci- ences, 64(4):820-842, 2002.","title":"Connectivity and inference problems for temporal networks","authors":"David Kempe, Jon Kleinberg, Amit Kumar","year":"2002","venue":"Journal of Computer and System Sciences","doi":null,"url":null,"internal_url":null},{"position":12,"raw":"[Klobas et al., 2022] Nina Klobas, George B Mertzios, Hen- drik Molter, and Paul G Spirakis. The complexity of com- puting optimum labelings for temporal connectivity. In 47th International Symposium on Mathematical Founda- tions of Computer Science (MFCS 2022), volume 241, page 62, 2022.","title":"The complexity of computing optimum labelings for temporal connectivity","authors":"Nina Klobas, Hendrik George B Mertzios, Paul G Molter, Spirakis","year":"2022","venue":"47th International Symposium on Mathematical Foundations of Computer Science (MFCS 2022)","doi":null,"url":null,"internal_url":null},{"position":13,"raw":"[Li et al., 2018] Lei Li, Kai Zheng, Sibo Wang, Wen Hua, and Xiaofang Zhou. Go slow to go fast: minimal on-road time route scheduling with parking facilities using histori- cal trajectory. The VLDB Journal, 27(3):321-345, 2018.","title":"Go slow to go fast: minimal on-road time route scheduling with parking facilities using historical trajectory","authors":"Lei Li, Kai Zheng, Sibo Wang, Wen Hua, Xiaofang Zhou","year":"2018","venue":"The VLDB Journal","doi":null,"url":null,"internal_url":null},{"position":14,"raw":"[Molter et al., 2021] Hendrik Molter, Malte Renken, and Philipp Zschoche. Temporal reachability minimization: Delaying vs. deleting. In Filippo Bonchi and Simon J. Puglisi, editors, 46th International Symposium on Math- ematical Foundations of Computer Science, MFCS 2021, August 23-27, 2021, Tallinn, Estonia, volume 202 of LIPIcs, pages 76:1-76:15. Schloss Dagstuhl -Leibniz- Zentrum für Informatik, 2021.","title":"Temporal reachability minimization: Delaying vs. deleting","authors":"Molter","year":"2021","venue":"th International Symposium on Mathematical Foundations of Computer Science, MFCS 2021","doi":null,"url":null,"internal_url":null},{"position":15,"raw":"[Thejaswi and Gionis, 2020] Suhas Thejaswi and Aristides Gionis. Restless reachability in temporal graphs. arXiv preprint arXiv:2010.08423, 2020.","title":"Restless reachability in temporal graphs","authors":"Suhas Thejaswi, Aristides Gionis","year":"2020","venue":null,"doi":null,"url":null,"internal_url":null},{"position":16,"raw":"[Wang et al., 2015] Sibo Wang, Wenqing Lin, Yi Yang, Xi- aokui Xiao, and Shuigeng Zhou. Efficient route planning on public transportation networks: A labelling approach. In Proc. of SIGMOD, pages 967-982. ACM, 2015.","title":"Efficient route planning on public transportation networks: A labelling approach","authors":"Sibo Wang, Wenqing Lin, Yi Yang, Xiaokui Xiao, Shuigeng Zhou","year":"2015","venue":"Proc. of SIGMOD","doi":null,"url":null,"internal_url":null},{"position":17,"raw":"[Whitbeck et al., 2012] John Whitbeck, Marcelo Dias de Amorim, Vania Conan, and Jean-Loup Guillaume. Tem- poral reachability graphs. In Mobicom, pages 377-388, 2012.","title":"Temporal reachability graphs","authors":"John Whitbeck, Marcelo Dias De Amorim, Vania Conan, Jean-Loup Guillaume","year":"2012","venue":"Mobicom","doi":null,"url":null,"internal_url":null},{"position":18,"raw":"[Wu et al., 2012] Lingkun Wu, Xiaokui Xiao, Dingxiong Deng, Gao Cong, Andy Diwen Zhu, and Shuigeng Zhou. Shortest path and distance queries on road net- works: An experimental evaluation. Proc. VLDB Endow., 5(5):406-417, 2012.","title":"Shortest path and distance queries on road networks: An experimental evaluation","authors":"Wu","year":"2012","venue":"Proc. VLDB Endow","doi":null,"url":null,"internal_url":null},{"position":19,"raw":"[Wu et al., 2014] Huanhuan Wu, James Cheng, Silu Huang, Yiping Ke, Yi Lu, and Yanyan Xu. Path problems in tem- poral graphs. Proc. of VLDB Endowment, 7(9):721-732, 2014.","title":"Path problems in temporal graphs","authors":"Huanhuan Wu, James Cheng, Silu Huang, Yiping Ke, Yi Lu, Yanyan Xu","year":"2014","venue":"Proc. of VLDB Endowment","doi":null,"url":null,"internal_url":null},{"position":20,"raw":"[Wu et al., 2016] Huanhuan Wu, Yuzhen Huang, James Cheng, Jinfeng Li, and Yiping Ke. Reachability and time- based path queries in temporal graphs. In Proc. of ICDE, pages 145-156. IEEE, 2016.","title":"Reachability and timebased path queries in temporal graphs","authors":"Huanhuan Wu, Yuzhen Huang, James Cheng, Jinfeng Li, Yiping Ke","year":"2016","venue":"Proc. of ICDE","doi":null,"url":null,"internal_url":null}],"license_note":"Copyright International Joint Conferences on Artificial Intelligence."}