Abstract
We first propose a method, called “bottom-up method” that, informally, “propagates” improvement of the worst-case complexity for “sparse” instances to “denser” ones and we show an easy though non-trivial application of it to the min set cover problem. We then tackle max independent set. Here, we propagate improvements of worst-case complexity from graphs of average degree d to graphs of average degree greater than d. Indeed, using algorithms for max independent set in graphs of average degree 3, we successively solve max independent set in graphs of average degree 4, 5 and 6. Then, we combine the bottom-up technique with measure and conquer techniques to get improved running times for graphs of maximum degree 5 and 6 but also for general graphs. The computation bounds obtained for max independent set are O ∗(1.1571n), O ∗(1.1895n) and O ∗(1.2050n), for graphs of maximum (or more generally average) degree 4, 5 and 6 respectively, and O ∗(1.2114n) for general graphs. These results improve upon the best known results for these cases for polynomial space algorithms.
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Beigel, R.: Finding maximum independent sets in sparse and general graphs. In: Proc. Symposium on Discrete Algorithms, SODA’99, pp. 856–857 (1999)
Bourgeois, N., Escoffier, B., Paschos, V.Th.: An O ∗(1.0977n) exact algorithm for max independent set in sparse graphs. In: Grohe, M., Niedermeier, R. (eds.) Proc. International Workshop on Exact and Parameterized Computation, IWPEC’08. Lecture Notes in Computer Science, vol. 5018, pp. 55–65. Springer, Berlin (2008)
Bourgeois, N., Escoffier, B., Paschos, V.Th., Van Rooij, J.M.M: Maximum independent set in graphs of average degree at most three in O(1.08537n). In: Kratochvíl, J., Li, A., Fiala, J., Kolman, P. (eds.) Proc. Conference on Theory and Applications of Models of Computation, TAMC’10. Lecture Notes in Computer Science, vol. 6108, pp. 373–384. Springer, Berlin (2010)
Chen, J., Liu, L., Jia, W.: Improvement on vertex cover for low-degree graphs. Networks 35(4), 253–259 (2000)
Chen, J., Kanj, I.A., Xia, G.: Labeled search trees and amortized analysis: improved upper bounds for NP-hard problems. Algorithmica 43(4), 245–273 (2005)
Dahllöf, V., Jonsson, P., Wahlström, M.: Counting models for 2SAT and 3SAT formulæ. Theor. Comput. Sci. 332(1–3), 265–291 (2005)
Fomin, F.V., Høie, K.: Pathwidth of cubic graphs and exact algorithms. Inf. Process. Lett. 97(5), 191–196 (2006)
Fomin, F.V., Gaspers, S., Saurabh, S., Stepanov, A.A.: On two techniques of combining branching and treewidth. Algorithmica 54(2), 181–207 (2009)
Fomin, F.V., Grandoni, F., Kratsch, D.: A measure & conquer approach for the analysis of exact algorithms. J. Assoc. Comput. Mach. 56(5), 1–32 (2009)
Fürer, M.: A faster algorithm for finding maximum independent sets in sparse graphs. In: Corea, J.R., Hevia, A., Kiwi, M. (eds.) Proc. Latin American Symposium on Theoretical Informatics, LATIN’06. Lecture Notes in Computer Science, vol. 3887, pp. 491–501. Springer, Berlin (2006)
Fürer, M., Kasiviswanathan, S.P.: Algorithms for counting 2-SAT solutions and colorings with applications. In: Kao, M.-Y., Li, X.-Y. (eds.) Proc. Algorithmic Aspects in Information and Management, AAIM’07. Lecture Notes in Computer Science, vol. 4508, pp. 47–57. Springer, Berlin (2007)
Goldberg, M.K., Spencer, T.H., Berque, D.A.: A low-exponential algorithm for counting vertex covers. In: Graph Theory, Combinatorics and Algorithms. Proc. 7th Quadrennial International Conference on the Theory and Application of Graphs, vol. 1, pp. 431–444. Wiley, New York (1992)
Kneis, J., Langer, A., Rossmanith, P.: A fine-grained analysis of a simple independent set algorithm. In: Kannan, R., Narayan Kumar, K. (eds.) Proc. Foundations of Software Technology and Theoretical Computer Science, FSTTCS’09. LIPIcs, vol. 4, pp. 287–298. Schloss Dagstuhl—Leibniz-Zentrum fuer Informatik (2009)
Kojevnikov, A., Kulikov, A.S.: A new approach to proving upper bounds for max-2-sat. In: Proc. Symposium on Discrete Algorithms, SODA’06, pp. 11–17 (2006)
Razgon, I.: Faster computation of maximum independent set and parameterized vertex cover for graphs with maximum degree 3. J. Discrete Algorithms 7, 191–212 (2009)
Robson, J.M.: Algorithms for maximum independent sets. J. Algorithms 7(3), 425–440 (1986)
Robson, J.M.: Finding a maximum independent set in time O(2n/4). Technical Report 1251-01, LaBRI, Université de Bordeaux I (2001)
van Rooij, J.M.M., Bodlaender, H.L.: Design by measure and conquer, a faster exact algorithm for dominating set. In: Albers, S., Weil, P. (eds.) Proc. International Symposium on Theoretical Aspects of Computer Science, STACS’08, pp. 657–668. Internationales Begegnungs- und Forschungszentrum für Informatik (IBFI), Schloss Dagstuhl, Germany (2008)
Wahlström, M.: A tighter bound for counting max-weight solutions to 2sat instances. In: Grohe, M., Niedermeier, R. (eds.) Proc. Parameterized and Exact Computation, Third International Workshop, IWPEC’08. Lecture Notes in Computer Science, vol. 5018, pp. 202–213. Springer, Berlin (2008)
Woeginger, G.J.: Exact algorithms for NP-hard problems: a survey. In: Juenger, M., Reinelt, G., Rinaldi, G. (eds.) Combinatorial Optimization—Eureka! You shrink! Lecture Notes in Computer Science, vol. 2570, pp. 185–207. Springer, Berlin (2003)
Xiao, M.: New branching rules: improvements on independent set and vertex cover in sparse graphs. CoRR (2009). arXiv:0904.2712
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Research supported by the French Agency for Research under the DEFIS program TODO, ANR-09-EMER-010. Parts of this paper have been presented at SWAT’10, LNCS 6139 and at TAMC’10, LNCS 6108.
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Bourgeois, N., Escoffier, B., Paschos, V.T. et al. Fast Algorithms for max independent set . Algorithmica 62, 382–415 (2012). https://doi.org/10.1007/s00453-010-9460-7
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DOI: https://doi.org/10.1007/s00453-010-9460-7