Abstract
Given a directed or undirected graph G=(V,E), a collection \({\mathcal{R}}=\{(S_{i},T_{i}) \mid i=1,2,\ldots,|{\mathcal{R}}|, S_{i},T_{i} \subseteq V, S_{i} \cap T_{i} =\emptyset\}\) of two disjoint subsets of V, and a requirement function \(r: {\mathcal{R}} \to\mathbb{R}_{+}\), we consider the problem (called area-to-area edge-connectivity augmentation problem) of augmenting G by a smallest number of new edges so that the resulting graph \(\hat{G}\) satisfies \(d_{\hat{G}}(X)\geq r(S,T)\) for all X⊆V, \((S,T) \in{\mathcal{R}}\) with S⊆X⊆V−T, where d G (X) denotes the degree of a vertex set X in G. This problem can be regarded as a natural generalization of the global, local, and node-to-area edge-connectivity augmentation problems.
In this paper, we show that there exists a constant c such that the problem is inapproximable within a ratio of \(c\log{|{\mathcal{R}}|}\), unless P=NP, even restricted to the directed global node-to-area edge-connectivity augmentation or undirected local node-to-area edge-connectivity augmentation. We also provide an \({\mathrm{O}}(\log{|{\mathcal{R}}|})\)-approximation algorithm for the area-to-area edge-connectivity augmentation problem, which is a natural extension of Kortsarz and Nutov’s algorithm (Kortsarz and Nutov, J. Comput. Syst. Sci., 74:662–670, 2008). This together with the negative result implies that the problem is \({\varTheta}(\log{|{\mathcal{R}}|})\)-approximable, unless P=NP, which solves open problems for node-to-area edge-connectivity augmentation in Ishii et al. (Algorithmica, 56:413–436, 2010), Ishii and Hagiwara (Discrete Appl. Math., 154:2307–2329, 2006), Miwa and Ito (J. Oper. Res. Soc. Jpn., 47:224–243, 2004).
Furthermore, we characterize the node-to-area and area-to-area edge-connectivity augmentation problems as the augmentation problems with modulotone and k-modulotone functions.
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Notes
Here we note that Hitting Set is equivalent to the set cover problem.
References
Benczúr, A.A., Frank, A.: Covering symmetric supermodular functions by graphs. Math. Program. 84, 483–503 (1999)
Bernath, A., Király, T.: A new approach to splitting off. In: Proceedings of the 13th International Conference on Integer Programming and Combinatoral Optimization, pp. 401–415 (2008)
Eswaran, K.P., Tarjan, R.E.: Augmentation problems. SIAM J. Comput. 5(4), 653–665 (1976)
Frank, A.: Augmenting graphs to meet edge-connectivity requirements. SIAM J. Discrete Math. 5(1), 25–53 (1992)
Frank, A.: Connectivity augmentation problems in network design. In: Birge, J.R., Murty, K.G. (eds.) Mathematical Programming: State of the Art 1994, pp. 34–63. University of Michigan Press, Ann Arbor (1994)
Fujito, T.: Approximation algorithms for submodular set cover with applications. IEICE Trans. Fundam. Electron. Commun. Comput. Sci. E83-D, 480–487 (2000)
Gabow, H.N.: Efficient splitting off algorithms for graphs. In: Proceedings of the 26th Annual ACM Symposium on the Theory of Computing, pp. 696–705 (1994)
Grötschel, M., Monma, C.L., Stoer, M.: Design of survivable networks. In: Network Models, Handbook in Operations Research and Management Science, vol. 7, pp. 617–672. North-Holland, Amsterdam (1995)
Ishii, T.: Minimum augmentation of edge-connectivity with monotone requirements in undirected graphs. Discrete Optim. 6, 23–36 (2009)
Ishii, T., Akiyama, Y., Nagamochi, H.: Minimum augmentation of edge-connectivity between vertices and sets of vertices in undirected graphs. Algorithmica 56, 413–436 (2010)
Ishii, T., Hagiwara, M.: Minimum augmentation of local edge-connectivity between vertices and vertex subsets in undirected graphs. Discrete Appl. Math. 154, 2307–2329 (2006)
Kortsarz, G., Nutov, Z.: Approximating minimum-cost connectivity problems. In: Gonzalez, T.F. (ed.) Handbook of Approximation Algorithms and Metaheuristics, vol. 58, pp. 1–21. Chapman & Hall/CRC Press, London/Boca Raton (2007)
Kortsarz, G., Nutov, Z.: Tight approximation algorithm for connectivity augmentation problems. J. Comput. Syst. Sci. 74, 662–670 (2008)
Miwa, H., Ito, H.: NA-edge-connectivity augmentation problem by adding edges. J. Oper. Res. Soc. Jpn. 47, 224–243 (2004)
Nagamochi, H.: Graph algorithms for network connectivity problems. J. Oper. Res. Soc. Jpn. 47, 199–223 (2004)
Nagamochi, H., Ibaraki, T.: Graph connectivity and its augmentation: applications of MA orderings. Discrete Appl. Math. 123, 447–472 (2002)
Nutov, Z.: Approximating connectivity augmentation problems. ACM Trans. Algorithms 6 (2009). doi:10.1145/1644015.1644020
Raz, R., Safra, S.: A sub-constant error-probability low-degree test and a sub-constant error-probability PCP characterization of NP. In: Proceedings of the 29th Annual ACM Symposium on the Theory of Computing, pp. 475–484 (1997)
Sakashita, M., Makino, K., Nagamochi, H., Fujishige, S.: Minimum transversals in posi-modular systems. SIAM J. Discrete Math. 23, 858–871 (2009)
Szigeti, Z.: Edge-connectivity augmentation of graphs over symmetric parity families. Discrete Math. 308, 6527–6532 (2008)
Szigeti, Z.: On edge-connectivity augmentation of graphs and hypergraphs. In: Cook, W., Lovasz, L., Vygen, J. (eds.) Research Trends in Combinatorial Optimization, pp. 483–521. Springer, Berlin (2009)
Watanabe, T., Nakamura, A.: Edge-connectivity augmentation problems. J. Comput. Syst. Sci. 35, 96–144 (1987)
Wolsey, L.A.: An analysis of the greedy algorithm for the submodular set covering problem. Combinatorica 2, 385–393 (1982)
Acknowledgements
We are very grateful to the anonymous referees for careful reading and suggestions. We would like to express our thanks to Hiroshi Nagamochi and Takuro Fukunaga for their helpful comments. This research was partially supported by the Scientific Grant-in-Aid from Ministry of Education, Culture, Sports, Science and Technology of Japan, the Inamori Foundation, and the Kayamori Foundation of Informational Science Advancement.
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An extended abstract of this paper was presented at 15th Computing: The Australasian Theory Symposium (CATS 2009), New Zealand, January 2009.
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Ishii, T., Makino, K. Augmenting Edge-Connectivity between Vertex Subsets. Algorithmica 69, 130–147 (2014). https://doi.org/10.1007/s00453-012-9724-5
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DOI: https://doi.org/10.1007/s00453-012-9724-5