Abstract
Given a k-vertex-connected graph G and a set S of extra edges (links), the goal of the k-vertex-connectivity augmentation problem is to find a subset \(S'\) of S of minimum size such that adding \(S'\) to G makes it \((k+1)\)-vertex-connected. Unlike the edge-connectivity augmentation problem, research for the vertex-connectivity version has been sparse.
In this work we present the first polynomial time approximation algorithm that improves the known ratio of 2 for 2-vertex-connectivity augmentation, for the case in which G is a cycle. This is the first step for attacking the more general problem of augmenting a 2-connected graph.
Our algorithm is based on local search and attains an approximation ratio of 1.8703. To derive it, we prove novel results on the structure of minimal solutions.
Waldo Gálvez is supported by the European Research Council, Grant Agreement No. 691672, project APEG. Francisco Sanhueza-Matamala is partially supported by grants ANID-PFCHA/Magíster Nacional/2020- 22201780 and FONDECYT Regular 1190043. Francisco Sanhueza-Matamala and José A. Soto are partially supported by ANID via FONDECYT Regular 1181180 and PIA AFB170001.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Notes
- 1.
For \(k\in \mathbb {N}\), a k-connected graph is a graph \(G=(V,E)\) satisfying that, for any \(V'\subseteq V\) with \(|V|\le k-1\), G remains connected after the deletion of \(V'\). If the definition holds when replacing nodes by edges, the graph is said to be k-edge-connected.
- 2.
A cactus is a 2-edge-connected graph where every edge belongs exactly to one cycle of the graph.
References
Adjiashvili, D.: Beating approximation factor two for weighted tree augmentation with bounded costs. ACM Trans. Algorithms 15(2), 19:1–19:26 (2019). https://doi.org/10.1145/3182395
Auletta, V., Dinitz, Y., Nutov, Z., Parente, D.: A 2-approximation algorithm for finding an optimum 3-vertex-connected spanning subgraph. J. Algorithms 32(1), 21–30 (1999). https://doi.org/10.1006/jagm.1999.1006
Basavaraju, M., Fomin, F.V., Golovach, P.A., Misra, P., Ramanujan, M.S., Saurabh, S.: Parameterized algorithms to preserve connectivity. In: Automata, Languages, and Programming - 41st International Colloquium, (ICALP). vol. 8572, pp. 800–811. Springer (2014). DOI: https://doi.org/10.1007/978-3-662-43948-7_66
Byrka, J., Grandoni, F., Ameli, A.J.: Breaching the 2-approximation barrier for connectivity augmentation: a reduction to steiner tree. In: Proccedings of the 52nd Annual ACM SIGACT Symposium on Theory of Computing (STOC). pp. 815–825. ACM (2020). https://doi.org/10.1145/3357713.3384301
Cecchetto, F., Traub, V., Zenklusen, R.: Bridging the gap between tree and connectivity augmentation: unified and stronger approaches. In: 53rd Annual ACM SIGACT Symposium on Theory of Computing (STOC). pp. 370–383. ACM (2021). https://doi.org/10.1145/3406325.3451086
Cheriyan, J., Gao, Z.: Approximating (Unweighted) Tree Augmentation via Lift-and-Project, Part I: Stemless TAP. Algorithmica 80(2), 530–559 (2017). https://doi.org/10.1007/s00453-016-0270-4
Cheriyan, J., Jordán, T., Ravi, R.: On 2-coverings and 2-packings of laminar families. In: Algorithms - 7th Annual European Symposium (ESA). vol. 1643, pp. 510–520. Springer (1999). https://doi.org/10.1007/3-540-48481-7_44
Cheriyan, J., Karloff, H.J., Khandekar, R., Könemann, J.: On the integrality ratio for tree augmentation. Oper. Res. Lett. 36(4), 399–401 (2008). https://doi.org/10.1016/j.orl.2008.01.009
Cohen, N., Nutov, Z.: A (1+ln2)-approximation algorithm for minimum-cost 2-edge-connectivity augmentation of trees with constant radius. Theor. Comput. Sci. 489–490, 67–74 (2013). https://doi.org/10.1016/j.tcs.2013.04.004
Dinitz, E., Karnazov, A., Lomonosov, M.: On the structure of the system of minimum edge cuts of a graph. Studies in Discrete Optimization pp. 290–306 (1976)
Even, G., Feldman, J., Kortsarz, G., Nutov, Z.: A 1.8 approximation algorithm for augmenting edge-connectivity of a graph from 1 to 2. ACM Trans. Algorithms 5(2), 21:1–21:17 (2009). https://doi.org/10.1145/1497290.1497297
Fiorini, S., Groß, M., Könemann, J., Sanità, L.: Approximating weighted tree augmentation via Chvátal-Gomory cuts. In: Proceedings of the Twenty-Ninth Annual ACM-SIAM Symposium on Discrete Algorithms (SODA). pp. 817–831. SIAM (2018). https://doi.org/10.1137/1.9781611975031.53
Frederickson, G.N., JáJá, J.: Approximation algorithms for several graph augmentation problems. SIAM J. Comput. 10(2), 270–283 (1981). https://doi.org/10.1137/0210019
Gálvez, W., Grandoni, F., Jabal Ameli, A., Sornat, K.: On the Cycle Augmentation Problem: Hardness and Approximation Algorithms. Theory of Computing Systems 65(6), 985–1008 (2021). https://doi.org/10.1007/s00224-020-10025-6
Goemans, M.X., Goldberg, A.V., Plotkin, S.A., Shmoys, D.B., Tardos, É., Williamson, D.P.: Improved approximation algorithms for network design problems. In: Proceedings of the Fifth Annual ACM-SIAM Symposium on Discrete Algorithms (SODA). pp. 223–232. ACM/SIAM (1994), http://dl.acm.org/citation.cfm?id=314464.314497
Grandoni, F., Kalaitzis, C., Zenklusen, R.: Improved approximation for tree augmentation: saving by rewiring. In: Proceedings of the 50th Annual ACM SIGACT Symposium on Theory of Computing (STOC). pp. 632–645. ACM (2018). https://doi.org/10.1145/3188745.3188898
Khuller, S., Thurimella, R.: Approximation algorithms for graph augmentation. J. Algorithms 14(2), 214–225 (1993). https://doi.org/10.1006/jagm.1993.1010
Khuller, S., Vishkin, U.: Biconnectivity approximations and graph carvings. J. ACM 41(2), 214–235 (1994). https://doi.org/10.1145/174652.174654
Kortsarz, G., Krauthgamer, R., Lee, J.R.: Hardness of approximation for vertex-connectivity network design problems. SIAM J. Comput. 33(3), 704–720 (2004). https://doi.org/10.1137/S0097539702416736
Kortsarz, G., Nutov, Z.: A simplified 1.5-approximation algorithm for augmenting edge-connectivity of a graph from 1 to 2. ACM Trans. Algorithms 12(2), 23:1–23:20 (2016). https://doi.org/10.1145/2786981
Kortsarz, G., Nutov, Z.: LP-relaxations for tree augmentation. Discret. Appl. Math. 239, 94–105 (2018). https://doi.org/10.1016/j.dam.2017.12.033
Mader, W.: Ecken vom gradn in minimalenn-fach zusammenhängenden graphen. Archiv der Mathematik 23(1), 219–224 (1972)
Marx, D., Végh, L.A.: Fixed-parameter algorithms for minimum-cost edge-connectivity augmentation. ACM Trans. Algorithms 11(4), 27:1–27:24 (2015). https://doi.org/10.1145/2700210
Nagamochi, H.: An approximation for finding a smallest 2-edge-connected subgraph containing a specified spanning tree. Discret. Appl. Math. 126(1), 83–113 (2003). https://doi.org/10.1016/S0166-218X(02)00218-4
Nutov, Z.: 2-node-connectivity network design. CoRR abs/2002.04048 (2020), https://arxiv.org/abs/2002.04048
Nutov, Z.: A \(4 + \varepsilon \) approximation for \(k\)-connected subgraphs. In: Proceedings of the 2020 ACM-SIAM Symposium on Discrete Algorithms (SODA). pp. 1000–1009. SIAM (2020). https://doi.org/10.1137/1.9781611975994.60
Nutov, Z.: On the Tree Augmentation Problem. Algorithmica 83(2), 553–575 (2020). https://doi.org/10.1007/s00453-020-00765-9
Spinrad, J.P.: Recognition of circle graphs. J. Algorithms 16(2), 264–282 (1994). https://doi.org/10.1006/jagm.1994.1012
Traub, V., Zenklusen, R.: A better-than-2 approximation for weighted tree augmentation. CoRR abs/2104.07114 (2021), https://arxiv.org/abs/2104.07114
Végh, L.A.: Augmenting undirected node-connectivity by one. SIAM J. Discret. Math. 25(2), 695–718 (2011). https://doi.org/10.1137/100787507
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2021 Springer Nature Switzerland AG
About this paper
Cite this paper
Gálvez, W., Sanhueza-Matamala, F., Soto, J.A. (2021). Approximation Algorithms for Vertex-Connectivity Augmentation on the Cycle. In: Koenemann, J., Peis, B. (eds) Approximation and Online Algorithms. WAOA 2021. Lecture Notes in Computer Science(), vol 12982. Springer, Cham. https://doi.org/10.1007/978-3-030-92702-8_1
Download citation
DOI: https://doi.org/10.1007/978-3-030-92702-8_1
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-030-92701-1
Online ISBN: 978-3-030-92702-8
eBook Packages: Computer ScienceComputer Science (R0)