Abstract
Given an on-going sports competition, with each team having a current score and some matches left to be played, we ask whether it is possible for our distinguished team t to obtain a final standing with at most r teams finishing before t. We study the computational complexity of this problem, addressing it both from the viewpoint of parameterized complexity and of approximation. We focus on a special case equivalent to finding a maximal induced subgraph of a given graph G that admits an orientation where the in-degree of each vertex is upper-bounded by a given function. We obtain a \(\varTheta (\log |V(G)|)\) approximation for this problem based on an asymptotically optimal approximation we present for a certain matroid problem in which we need to cover a base of a matroid by picking elements from a set family.
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04 October 2017
The authors regret the following error in their article “A connection between sports and matroids: How many teams can we beat?” (Algorithmica, doi: 10.1007/s00453-016-0256-2), considering the computational complexity of the problem MinStanding(S). In Theorem 3 of our paper [4], we erroneously claimed a $$\mathsf {W}[1]$$ W [ 1 ] -hardness result to hold even for the case where the undirected version of the input graph is claw-free. In fact, we can only prove the theorem for $$K_{1,4}$$ K 1 , 4 -free graphs, so the property claw-free should have been replaced by the property $$K_{1,4}$$ K 1 , 4 -free.
Notes
Actually we need certain small technical assumptions on S, essentialy to rule out the degenerate case when the matches can only have one possible outcome.
In fact, this situation occurs at latest when each team has at most one remaining match to be played.
In fact, Richey and Punnen [27] proved \(\mathsf {NP}\)-hardness for a slightly more general version of this problem, but their reduction proves the stronger result stated here.
References
Adler, I., Erera, A.L., Hochbaum, D.S., Olinick, E.V.: Baseball, optimization and the world wide web. Interfaces 32(2), 12–22 (2002)
Asahiro, Y., Jansson, J., Miyano, E., Ono, H.: Upper and lower degree bounded graph orientation with minimum penalty. In: CATS 2012: Proceedings of the 18th Computing: The Australasian Theory Symposium, vol. 128 of Conferences in Research and Practice in Information Technology, pp. 139–146. (2012)
Bernholt, T., Gülich, A., Hofmeister, T., Schmitt, N.: Football elimination is hard to decide under the 3-point-rule. In: MFCS 1999: Proceedings of the 24th International Symposium on Mathematical Foundations of Computer Science, volume 1672 of Lecture Notes in Computer Science, pp. 410–418. Springer, (1999)
Cechlárová, K., Potpinková, E., Schlotter, I.: Refining the complexity of the sports elimination problem. Discrete Appl. Math. 199, 172–186 (2016)
Chrobak, M., Eppstein, D.: Planar orientations with low out-degree and compaction of adjacency matrices. Theor. Comput. Sci. 86, 243–266 (1991)
Diestel, R.: Graph Theory, Volume 173 of Graduate Texts in Mathematics, vol. 173. Springer-Verlag, Berlin (2005)
Disser, Y., Matuschke, J.: Degree-constrained orientations of embedded graphs. J. Comb. Opt. 31(2), 758–773 (2016)
Downey, R.G., Fellows, M.R.: Fundamentals of Parameterized Complexity. Texts in Computer Science. Springer, London (2013)
Downey, R.G., Fellows, M.R.: Parameterized Complexity. Monographs in Computer Science. Springer-Verlag, New York (1999)
Felsner, S.: Lattice structures from planar graphs. Electron. J. Comb. 11, R15 (2004)
Frank, A., Gyárfás, A.: How to orient the edges of a graph. Colloq. Math. Soc. János Bolyai 18, 353–364 (1976)
Garey, M.R., Johnson, D.S.: Computers and Intractability: A Guide to the Theory of NP-Completeness. A Series of Books in the Mathematical Sciences. W. H. Freeman & Co., New York (1979)
Gonzalez, T.F.: Clustering to minimize the maximum intercluster distance. Theor. Comput. Sci. 38, 293–306 (1985)
Gusfield, D., Martel, C.U.: A fast algorithm for the generalized parametric minimum cut problem and applications. Algorithmica 7(5&6), 499–519 (1992)
Gusfield, D., Martel, C.U.: The structure and complexity of sports elimination numbers. Algorithmica 32(1), 73–86 (2002)
Hakimi, S.L.: On the degrees of the vertices of a directed graph. J. Franklin Inst. 279, 290–308 (1965)
Hermelin, D., Mnich, M., Leeuwen, E.J.: Parameterized complexity of induced \(H\)-matching on claw-free graphs. In: ESA 2012: Proceedings of the 16th Annual European Symposium on Algorithms, volume 7501 of Lecture Notes in Computer Science, pp. 624–635. Springer (2012)
Hoffman, A.J., Rivlin, T.J.: When is a team “mathematically” eliminated?. In: Proceedings of the Princeton Symposium on Mathematical Programming, pp. 391–401. Princeton University Press (1970)
Kern, W., Paulusma, D.: The new fifa rules are hard: complexity aspects of sports competitions. Discrete Appl. Math. 108(3), 317–323 (2001)
Kern, W., Paulusma, D.: The computational complexity of the elimination problem in generalized sports competitions. Discrete Opt. 1(2), 205–214 (2004)
Lawler, E.L.: Combinatorial optimization: networks and matroids. Dover Books on Mathematics, Courier Corporation (2012)
McCormick, S.T.: Fast algorithms for parametric scheduling come from extensions to parametric maximum flow. Op. Res. 47(5), 744–756 (1999)
Moshkovitz, D.: The projection games conjecture and the NP-hardness of \(\ln n\)-approximating Set-Cover. Theor. Comput. 11, 221–235 (2015)
Neumann, S., Wiese, A.: This house proves that debating is harder than soccer. In: FUN 2016: Proceedings of the 8th International Conference on Fun with Algorithms, pp. 25:1–25:14 (2016)
Oxley, J.G.: Matroid Theory. Oxford graduate texts in mathematics. Oxford University Press, Oxford (2006)
Perfect, H.: Applications of menger’s graph theorem. J. Math. Anal. Appl. 22, 96–110 (1968)
Richey, M.B., Punnen, A.P.: Minimum perfect bipartite matchings and spanning trees under categorization. Discrete Appl. Math. 39, 147–153 (1992)
Robinson, L.W.: Baseball playoff eliminations: an application of linear programming. Op. Res. Lett. 10(2), 67–74 (1991)
Schwartz, B.L.: Possible winners in partially completed tournaments. SIAM Rev. 8, 302–308 (1966)
Wayne, K.D.: A new property and a faster algorithm for baseball elimination. SIAM J. Discrete Math. 14(2), 223–229 (2001)
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I. Schlotter: Supported by the Hungarian Scientific Research Fund (OTKA Grants Nos. K-108383 and K-108947).
K. Cechlárová: Supported by the grants VEGA 1/0344/14, VEGA 1/0142/15, and APVV-15-0091.
A correction to this article is available online at https://doi.org/10.1007/s00453-017-0378-1.
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Schlotter, I., Cechlárová, K. A Connection Between Sports and Matroids: How Many Teams Can We Beat?. Algorithmica 80, 258–278 (2018). https://doi.org/10.1007/s00453-016-0256-2
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DOI: https://doi.org/10.1007/s00453-016-0256-2