Abstract
We consider bounded width CNF-formulas where the width is measured by popular graph width measures on graphs associated to CNF-formulas. Such restricted graph classes, in particular those of bounded treewidth, have been extensively studied for their uses in the design of algorithms for various computational problems on CNF-formulas. Here we consider the expressivity of these formulas in the model of clausal encodings with auxiliary variables. We first show that bounding the width for many of the measures from the literature leads to a dramatic loss of expressivity, restricting the formulas to such of low communication complexity. We then show that the width of optimal encodings with respect to different measures is strongly linked: there are two classes of width measures, one containing primal treewidth and the other incidence cliquewidth, such that in each class the width of optimal encodings only differs by constant factors. Moreover, between the two classes the width differs at most by a factor logarithmic in the number of variables. Both these results are in stark contrast to the setting without auxiliary variables where all width measures we consider here differ by more than constant factors and in many cases even by linear factors.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Similar content being viewed by others
References
Amarilli, A., Capelli, F., Monet, M., Senellart, P.: Connecting knowledge compilation classes and width parameters CoRR, abs/1811.02944 (2018)
Amarilli, A., Monet, M., Senellart, P.: Connecting width and structure in knowledge compilation. In: 21st International Conference on Database Theory, ICDT, Vienna, Austria, 26–29 March 2018 (2018)
Biere, A., Heule, M., van Maaren, H., Walsh, T. (eds.): Handbook of Satisfiability, volume 185 of Frontiers in Artificial Intelligence and Applications. IOS Press (2009)
Bova, S., Capelli, F., Mengel, S., Slivovsky, F.: On compiling CNFs into structured deterministic DNNFs. In: Heule, M., Weaver, S. (eds.) SAT 2015. LNCS, vol. 9340, pp. 199–214. Springer, Cham (2015). https://doi.org/10.1007/978-3-319-24318-4_15
Bova, S., Capelli, F., Mengel, S., Slivovsky, F.: Knowledge compilation meets communication complexity. In: Proceedings of the Twenty-Fifth International Joint Conference on Artificial Intelligence, IJCAI 2016 (2016)
Bova, S., Szeider, S.: Circuit treewidth, sentential decision, and query compilation (2017)
Brault-Baron, J., Capelli, F., Mengel, S.: Understanding model counting for \(\beta \)-acyclic CNF-formulas CoRR, abs/1405.6043 (2014)
Briquel, I., Koiran, P., Meer, K.: On the expressive power of CNF formulas of bounded tree- and clique-width. Discrete Appl. Math. 159(1), 1–14 (2011)
Capelli, F., Mengel, S.: Tractable QBF by knowledge compilation. In: 36th International Symposium on Theoretical Aspects of Computer Science, STACS 2019, vol. 126, pp. 18:1–18:16 (2019)
Chen, H.: Quantified constraint satisfaction and bounded treewidth. In: Proceedings of the 16th Eureopean Conference on Artificial Intelligence, ECAI 2004 (2004)
Darwiche, A., Marquis, P.: A knowledge compilation map. J. Artif. Intell. Res. 17, 229–264 (2002)
Diestel, R.: Graph Theory. Volume 173 of Graduate texts in Mathematics, 4th edn. Springer, Heidelberg (2012)
Fischer, E., Makowsky, J., Ravve, E.: Counting truth assignments of formulas of bounded tree-width or clique-width. Discrete Appl. Math. 156(4), 511–529 (2008)
Ganian, R., Szeider, S.: New width parameters for model counting. In: Gaspers, S., Walsh, T. (eds.) SAT 2017. LNCS, vol. 10491, pp. 38–52. Springer, Cham (2017). https://doi.org/10.1007/978-3-319-66263-3_3
Gaspers, S., Szeider, S.: Strong backdoors to bounded treewidth SAT. In: 54th Annual IEEE Symposium on Foundations of Computer Science, FOCS 2013 (2013)
Gent, I.P., Nightingale, P.: A new encoding of AllDifferent into SAT. In: International Workshop on Modelling and Reformulating Constraint Satisfaction Problems (2004)
Giunchiglia, E., Maratea, E., Tacchella, A.: Dependent and independent variables in propositional satisfiability. In: Logics in Artificial Intelligence. JELIA 2002 (2002)
Golumbic, M.C., Gurvich, V.: Read-once functions. In: Boolean Functions: Theory, Algorithms and Applications, pp. 519–560 (2011)
Gottlob, G., Pichler, R., Wei, F.: Bounded treewidth as a key to tractability of knowledge representation and reasoning. Artif. Intell., 174(1), 105–132 (2010)
Jakl, M., Pichler, R., Woltran, S.: Answer-set programming with bounded treewidth. In: Proceedings of the 21st International Joint Conference on Artificial Intelligence. IJCAI 2009 (2009)
Krause, M.: Exponential lower bounds on the complexity of local and real-time branching programs. Elektronische Informationsverarbeitung und Kybernetik 24(3), 99–110 (1988)
Kushilevitz, E., Nisan, N.: Communication Complexity. Cambridge University Press, Cambridge (1997)
Lampis, M., Mengel, S., Mitsou, V.: QBF as an alternative to Courcelle’s theorem. In: Beyersdorff, O., Wintersteiger, C.M. (eds.) SAT 2018. LNCS, vol. 10929, pp. 235–252. Springer, Cham (2018). https://doi.org/10.1007/978-3-319-94144-8_15
Paulusma, D., Slivovsky, F., Szeider, S.: Model counting for CNF formulas of bounded modular treewidth. In: 30th International Symposium on Theoretical Aspects of Computer Science, STACS 2013 (2013)
Paulusma, D., Slivovsky, F., Szeider, S.: Model counting for CNF formulas of bounded modular treewidth. Algorithmica 76(1), 168–194 (2016)
Pipatsrisawat, K., Darwiche, A.: New compilation languages based on structured decomposability. In: Proceedings of the Twenty-Third AAAI Conference on Artificial Intelligence, AAAI 2008 (2008)
Pipatsrisawat, T., Darwiche, A.: A lower bound on the size of decomposable negation normal form. In: Proceedings of the Twenty-Fourth AAAI Conference on Artificial Intelligence, AAAI 2010 (2010)
Sæther, S.H., Telle, J.A., Vatshelle, M.: Solving #SAT and MAXSAT by dynamic programming. J. Artif. Intell. Res. 54, 59–82 (2015)
Samer, M., Szeider, S.: Algorithms for propositional model counting. J. Discrete Algorithms 8(1), 50–64 (2010)
Samer, M., Szeider, S.: Constraint satisfaction with bounded treewidth revisited. J. Comput. Syst. Sci. 76(2), 103–114 (2010)
Sinz, C.: Towards an optimal CNF encoding of boolean cardinality constraints. In: 11th International Conference Principles and Practice of Constraint Programming - CP 2005. CP 2005 (2005)
Slivovsky, F., Szeider, S.: Model counting for formulas of bounded clique-width. In: 24th International Symposium on Algorithms and Computation. ISAAC 2013 (2013)
Vatshelle, M.: New width parameters of graphs. Ph.D. Thesis, University of Bergen (2012)
Wegener, I.: Branching Programs and Binary Decision Diagrams. SIAM (2000)
Acknowledgements
The authors are grateful to the anonymous reviewers for their comments, which greatly helped to improve the presentation of the paper. The first author would also like to thank David Mitchell for asking the right question at the right moment. This paper grew largely out of an answer to this question.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2019 Springer Nature Switzerland AG
About this paper
Cite this paper
Mengel, S., Wallon, R. (2019). Revisiting Graph Width Measures for CNF-Encodings. In: Janota, M., Lynce, I. (eds) Theory and Applications of Satisfiability Testing – SAT 2019. SAT 2019. Lecture Notes in Computer Science(), vol 11628. Springer, Cham. https://doi.org/10.1007/978-3-030-24258-9_16
Download citation
DOI: https://doi.org/10.1007/978-3-030-24258-9_16
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-030-24257-2
Online ISBN: 978-3-030-24258-9
eBook Packages: Computer ScienceComputer Science (R0)