Abstract
We study the complexity of restricted versions of s-t-connectivity, which is the standard complete problem for \(\mathsf{NL}\) . In particular, we focus on different classes of planar graphs, of which grid graphs are an important special case. Our main results are:
-
Reachability in graphs of genus one is logspace-equivalent to reachability in grid graphs (and in particular it is logspace-equivalent to both reachability and non-reachability in planar graphs).
-
Many of the natural restrictions on grid-graph reachability (GGR) are equivalent under \(\mathsf{AC}^{0}\) reductions (for instance, undirected GGR, outdegree-one GGR, and indegree-one-outdegree-one GGR are all equivalent). These problems are all equivalent to the problem of determining whether a completed game position in HEX is a winning position, as well as to the problem of reachability in mazes studied by Blum and Kozen (IEEE Symposium on Foundations of Computer Science (FOCS), pp. 132–142, [1978]). These problems provide natural examples of problems that are hard for \(\mathsf{NC}^{1}\) under \(\mathsf{AC}^{0}\) reductions but are not known to be hard for \(\mathsf{L}\) ; they thus give insight into the structure of \(\mathsf{L}\) .
-
Reachability in layered planar graphs is logspace-equivalent to layered grid graph reachability (LGGR). We show that LGGR lies in \(\mathsf{UL}\) (a subclass of \(\mathsf{NL}\) ).
-
Series-Parallel digraphs (on which reachability was shown to be decidable in logspace by Jakoby et al.) are a special case of single-source-single-sink planar directed acyclic graphs (DAGs); reachability for such graphs logspace reduces to single-source-single-sink acyclic grid graphs. We show that reachability on such grid graphs \(\mathsf{AC}^{0}\) reduces to undirected GGR.
-
We build on this to show that reachability for single-source multiple-sink planar DAGs is solvable in \(\mathsf{L}\) .
Similar content being viewed by others
References
Allender, E., Mahajan, M.: The complexity of planarity testing. Inf. Comput. 189, 117–134 (2004)
Allender, E., Reinhardt, K., Zhou, S.: Isolation, matching, and counting: Uniform and nonuniform upper bounds. J. Comput. Syst. Sci. 59(2), 164–181 (1999)
Allender, E., Datta, S., Roy, S.: The directed planar reachability problem. In: Proc. 25th Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FST&TCS). Lecture Notes in Computer Science, vol. 1373, pp. 238–249. Springer, Berlin (2005)
Allender, E., Barrington, D.A.M., Chakraborty, T., Datta, S., Roy, S.: Grid graph reachability problems. In: IEEE Conference on Computational Complexity, pp. 299–313 (2006)
Barrington, D.A.: Bounded-width polynomial-size branching programs recognize exactly those languages in NC1. J. Comput. Syst. Sci. 38, 150–164 (1989)
Barrington, D.A.M., Lu, C.-J., Miltersen, P.B., Skyum, S.: Searching constant width mazes captures the AC0 hierarchy. In: 15th International Symposium on Theoretical Aspects of Computer Science (STACS). Lecture Notes in Computer Science, vol. 1373, pp. 73–83. Springer, Berlin (1998)
Blum, M., Kozen, D.: On the power of the compass (or, why mazes are easier to search than graphs). In: IEEE Symposium on Foundations of Computer Science (FOCS), pp. 132–142 (1978)
Bourke, C., Tewari, R., Vinodchandran, N.V.: Directed planar reachability is in unambiguous logspace. In: IEEE Conference on Computational Complexity, pp. 217–221 (2007)
Buhrman, H., Spaan, E., Torenvliet, L.: The relative power of logspace and polynomial time reductions. Comput. Complex. 3, 231–244 (1993)
Buss, S.: Polynomial-size Frege and resolution proofs of st-connectivity and Hex tautologies. Theor. Comput. Sci. 357, 35–52 (2006)
Buss, S.R., Hay, L.: On truth-table reducibility to SAT. Inf. Comput. 91(1), 86–102 (1991)
Buss, S.R., Cook, S., Gupta, A., Ramachandran, V.: An optimal parallel algorithm for formula evaluation. SIAM J. Comput. 21(4), 755–780 (1992)
Chakraborty, T., Datta, S.: One-input-face MPCVP is hard for L, but in LogDCFL. In: Conference on Foundations of Software Technology and Theoretical Computer Science (FST&TCS). Lecture Notes in Computer Science, vol. 4337, pp. 57–68. Springer, Berlin (2006)
Cook, S.A., McKenzie, P.: Problems complete for deterministic logarithmic space. J. Algorithms 8, 385–394 (1987)
Datta, S., Kulkarni, R., Limaye, N., Mahajan, M.: Planarity, determinants, permanents, and (unique) matchings. In: Computer Science—Theory and Applications, Second International Symposium on Computer Science in Russia, (CSR 2007). Lecture Notes in Computer Science, vol. 4649, pp. 115–126. Springer, Berlin (2007)
Eppstein, D., Italiano, G.F., Tamassia, R., Tarjan, R.E., Westbrook, J.R., Yung, M.: Maintenance of a minimum spanning forest in a dynamic planar graph. J. Algorithms 13(1), 33–54 (1992). (Corrigendum in vol. 15, 1993)
Etessami, K.: Counting quantifiers, successor relations, and logarithmic space. J. Comput. Syst. Sci. 54(3), 400–411 (1997)
Gross, J., Tucker, T.: Topological Graph Theory, 1st edn. Wiley, New York (1987)
Halldórsson, M., Radhakrishnan, J., Subrahmanyam, K.V.: Directed vs. undirected monotone contact networks for threshold functions. In: IEEE Symposium on Foundations of Computer Science (FOCS), pp. 604–613 (1993)
Henzinger, M.R., Klein, P., Rao, S., Subramanian, S.: Faster shortest-path algorithms for planar graphs. J. Comput. Syst. Sci. 55(1), 3–23 (1997)
Husfeldt, T.: Fully dynamic transitive closure in plane dags with one source and one sink. In: Proc. 3rd ESA. Lecture Notes in Computer Science, vol. 955, pp. 199–212. Springer, Berlin (1995)
Immerman, N.: Languages that capture complexity classes. SIAM J. Comput. 16(4), 760–778 (1987)
Immerman, N.: Nondeterministic space is closed under complementation. SIAM J. Comput. 17, 935–938 (1988)
Immerman, N.: Descriptive Complexity. Springer Graduate Texts in Computer Science. Springer, Berlin (1998)
Jakoby, A., Tantau, T.: Personal communication (2006)
Jakoby, A., Tantau, T.: Logspace algorithms for computing shortest and longest paths in series-parallel graphs. In: Conference on Foundations of Software Technology and Theoretical Computer Science (FST&TCS), pp. 216–227 (2007)
Jakoby, A., Liskiewicz, M., Reischuk, R.: Space efficient algorithms for directed series-parallel graphs. J. Algorithms 60, 85–114 (2006)
Ladner, R., Lynch, N.: Relativization of questions about log space reducibility. Math. Syst. Theory 10, 19–32 (1976)
Lange, K.-J.: An unambiguous class possessing a complete set. In: 14th International Symposium on Theoretical Aspects of Computer Science (STACS). Lecture Notes in Computer Science, vol. 1200, pp. 339–350. Springer, Berlin (1997)
Limaye, N., Mahajan, M., Sarma, J.M.N.: Evaluating monotone circuits on cylinders, planes, and torii. In: Proc. 23rd Symposium on Theoretical Aspects of Computing (STACS). Lecture Notes in Computer Science, pp. 660–671. Springer, Berlin (2006)
Mahajan, M., Varadarajan, K.R.: A new NC-algorithm for finding a perfect matching in bipartite planar and small genus graphs. In: ACM Symposium on Theory of Computing (STOC), pp. 351–357 (2000)
Mohar, B., Thomassen, C.: Graphs on Surfaces, 1st edn. John Hopkins University Press, Baltimore (2001)
Nisan, N., Ta-Shma, A.: Symmetric logspace is closed under complement. Chicago J. Theor. Comput. Sci. (1995)
Papakostas, A.: Upward planarity testing of outerplanar dags. In: Graph Drawing (GD94). Lecture Notes in Computer Science, vol. 894, pp. 298–306. Springer, Berlin (1995)
Reingold, O.: Undirected ST-connectivity in log-space. In: Proceedings of the 37th Symposium on Foundations of Computer Science, pp. 376–385. IEEE Computer Society Press (2005)
Reinhardt, K., Allender, E.: Making nondeterminism unambiguous. SIAM J. Comput. 29, 1118–1131 (2000)
Szelepcsényi, R.: The method of forced enumeration for nondeterministic automata. Acta Inf. 26, 279–284 (1988)
Thierauf, T., Wagner, F.: The isomorphism problem for planar 3-connected graphs is in unambiguous logspace. In: 25th Annual Symposium on Theoretical Aspects of Computer Science (STACS), pp. 633–644 (2008)
Thomassen, C.: Embeddings of graphs with no short noncontractible cycles. J. Comb. Theory Ser. B 48(2), 155–177 (1990)
Yang, H.: An NC algorithm for the general planar monotone circuit value problem. In: SPDP: 3rd IEEE Symposium on Parallel and Distributed Processing. ACM Special Interest Group on Computer Architecture (SIGARCH) and IEEE Computer Society (1991)
Yannakakis, M.: Embedding planar graphs in four pages. J. Comput. Syst. Sci. 38(1), 36–67 (1989)
Author information
Authors and Affiliations
Corresponding author
Additional information
E. Allender supported in part by NSF Grant CCF-0514155.
D.A. Mix Barrington supported in part by NSF Grant CCR-9988260.
S. Roy supported in part by NSF Grant CCF-0514155.
Rights and permissions
About this article
Cite this article
Allender, E., Mix Barrington, D.A., Chakraborty, T. et al. Planar and Grid Graph Reachability Problems. Theory Comput Syst 45, 675–723 (2009). https://doi.org/10.1007/s00224-009-9172-z
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00224-009-9172-z