Abstract
In this paper we consider the checkpoint problem. The input consists of an undirected graph G, a set of source-destination pairs {(s 1,t 1), ...,(s k ,t k )}, and a collection \({\cal P}\) of paths connecting the (s i ,t i ) pairs. A feasible solution is a multicut E′; namely, a set of edges whose removal disconnects every source-destination pair. For each \(p\in {\cal P}\) we define cp E′(p) = |p ∩ E′|. In the sum checkpoint (SCP) problem the goal is to minimize \(\sum_{p \in \mathcal{P}} {\mathsf{cp}}_{E'}(p)\), while in the maximum checkpoint (MCP) problem the goal is to minimize \(\max_{p \in \mathcal{P}} {\mathsf{cp}}_{E'}(p)\). These problem have several natural applications, e.g., in urban transportation and network security. In a sense, they combine the multicut problem and the minimum membership set cover problem.
For the sum objective we show that weighted SCP is equivalent, with respect to approximability, to undirected multicut. Thus there exists an O(logn) approximation for SCP in general graphs.
Our current approximability results for the max objective have a wide gap: we provide an approximation factor of \(O\big(\!\sqrt{n\log n}/{\mathsf{opt}}\,\big)\) for MCP and a hardness of 2 under the assumption P ≠ NP. The hardness holds for trees, in which case we can obtain an asymptotic approximation factor of 2.
Finally we show strong hardness for the well-known problem of finding a path with minimum forbidden pairs, which in a sense can be considered the dual to the checkpoint problem. Despite various works on this problem, hardness of approximation was not known prior to this work. We show that the problem cannot be approximated within c n for some constant c > 0, unless P = NP. This is the strongest type of hardness possible. It carries over to directed acyclic graphs and is a huge improvement over the plain NP-hardness of Gabow (SIAM J. Comp 2007, pages 1648–1671).
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Chawla, S., Krauthgamer, R., Kumar, R., Rabani, Y., Sivakumar, D.: On the hardness of approximating multicut and sparsest-cut. Computational Complexity 15(2), 94–114 (2006)
Chen, T., Kao, M.Y., Tepel, M., Rush, J., Church, G.: A dynamic programming approach to de novo peptide sequencing via tandem mass spectrometry. Journal of Computational Biology 8(3), 325–337 (2001)
Demaine, E.D., Feige, U., Hajiaghayi, M.T., Salavatipour, M.: Combination can be hard: approximability of the unique coverage problem. SIAM J. Comp. 38(4), 1464–1483 (2008)
Dinur, I., Safra, S.: The importance of being biased. In: STOC, pp. 33–42 (2002)
Gabow, H., Maheswari, S., Osterweil, L.: On two problems in the generation of program test paths. IEEE Trans. Software Eng. 2(3), 227–231 (1976)
Gabow, H.N.: Finding paths and cycles of superpolylogarithmic length. SIAM J. Comp. 36(6), 1648–1671 (2007)
Garg, N., Vazirani, V., Yannakakis, M.: Primal-dual approximation algorithms for integral flow and multicut in trees. Algorithmica 18(1), 3–20 (1997)
Garg, N., Vazirani, V.V., Yannakakis, M.: Approximate max-flow min-(multi) cut theorems and their applications. SIAM Journal on Computing 25(2), 235–251 (1996)
Håstad, J.: Some optimal inapproximability results. J. of the ACM 48(4), 798–859 (2001)
Hochbaum, D.: Approximation algorithms for NP-hard problems. PWS Publishing Co. (1997)
Khot, S.: On the unique games conjecture. In: FOCS, p. 3 (2005)
Kolman, P., Pangrac, O.: On the complexity of paths avoiding forbidden pairs. Discrete applied math. 157, 2871–2877 (2009)
Kortsarts, Y., Kortsarz, G., Nutov, Z.: Greedy approximation algorithms for directed multicuts. Networks 45(4), 214–217 (2005)
Kortsarz, G.: On the hardness of approximating spanners. Algorithmica 30(3), 432–450 (2001)
Krause, K., Smith, R., Goodwin, M.: Optimal software test planning through authomated search analysis. In: IEEE Symp. Computer Software Reliability, pp. 18–22 (1973)
Kuhn, F., von Rickenbach, P., Wattenhofer, R., Welzl, E., Zollinger, A.: Interference in cellular networks: The minimum membership set cover problem. In: Wang, L. (ed.) COCOON 2005. LNCS, vol. 3595, pp. 188–198. Springer, Heidelberg (2005)
Nelson, J.: Notes on min-max multicommodity cut on paths and trees. Manuscript (2009)
Schaefer, T.J.: The complexity of satisfiability problems. In: Proc. of the 10th of the Tenth Annual ACM Symposium on Theory of Computing, pp. 216–226 (1978)
Strimani, P., Sinha, B.: Impossible pair-constrained test path generation in a program. Information Sciences 28, 87–103 (1982)
Varadarajan, K., Venkataraman, G.: Graph decomposition and a greedy algorithm for edge-disjoint paths. In: SODA, pp. 379–380 (2004)
Yannakakis, M.: On a class of totally unimodular matrices. In: FOCS, pp. 10–16 (1980)
Yinnone, H.: On paths avoiding forbidden pairs of vertices in a graph. Discrete Appl. Math. 74(1), 85–92 (1997)
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2010 Springer-Verlag Berlin Heidelberg
About this paper
Cite this paper
Hajiaghayi, M., Khandekar, R., Kortsarz, G., Mestre, J. (2010). The Checkpoint Problem. In: Serna, M., Shaltiel, R., Jansen, K., Rolim, J. (eds) Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques. RANDOM APPROX 2010 2010. Lecture Notes in Computer Science, vol 6302. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-15369-3_17
Download citation
DOI: https://doi.org/10.1007/978-3-642-15369-3_17
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-642-15368-6
Online ISBN: 978-3-642-15369-3
eBook Packages: Computer ScienceComputer Science (R0)