Abstract
In the traditional maximum-flow problem, the goal is to transfer maximum flow in a network by directing, in each vertex in the network, incoming flow to outgoing edges. The problem corresponds to settings in which a central authority has control on all vertices of the network. Today’s computing environment, however, involves systems with no central authority. In particular, in many applications of flow networks, the vertices correspond to decision-points controlled by different and selfish entities. For example, in communication networks, routers may belong to different companies, with different destination objectives. This suggests that the maximum-flow problem should be revisited, and examined from a game-theoretic perspective. We introduce and study multi-player flow games (MFGs, for short). Essentially, the vertices of an MFG are partitioned among the players, and a player that owns a vertex directs the flow that reaches it. Each player has a different target vertex, and the objective of each player is to maximize the flow that reaches her target vertex. We study the stability of MFGs and show that, unfortunately, an MFG need not have a Nash Equilibrium. Moreover, the price of anarchy and even the price of stability of MFGs are unbounded. That is, the reduction in the flow due to selfish behavior is unbounded. We study the problem of deciding whether a given MFG has a Nash Equilibrium and show that it is \(\Sigma _2^P\)-complete, as well as the problem of finding optimal strategies for the players (that is, best-response moves), which we show to be NP-complete. We continue with some good news and consider a variant of MFGs in which flow may be swallowed. For example, when routers in a communication network may drop messages. We show that, surprisingly, while this model seems to incentivize selfish behavior, a Nash Equilibrium that achieves the maximum flow always exists, and can be found in polynomial time. Finally, we consider MFGs in which the strategies of the players may use non-integral flows, which we show to be stronger.
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Notes
Not to confuse with games in which players cooperate in order to construct a sub-graph that maximizes the flow in the traditional setting, which are also termed flow games (c.f., [16]).
Throughout this paper, we consider pure strategies. Unlike mixed strategies, pure strategies are not random nor drawn from a distribution.
Different aspects of networks have already been extensively studied from the perspectives of algorithmic game theory. This includes, for example, network formation games [4] or incentive issues in interdomain routing and the BGP protocol [11]. We are the first, however, to consider the maximum-flow problem from this perspective.
References
Agarwal, S., Kodialam, M. S., & Lakshman, T. V. (2013). Traffic engineering in software defined networks. In Proceedings of 32nd IEEE international conference on computer communications, pp. 2211–2219.
Ahuja, R. K., Magnanti, T. L., & Orlin, J. B. (1993). Network flows: Theory, algorithms, and applications. Englewood Cliffs: Prentice Hall.
Almagor, S., Avni, G., & Kupferman, O. (2015). Automatic generation of quality specifications. In Proceedings of 26th international conference on concurrency theory, vol. 42, pp. 325–339.
Anshelevich, E., Dasgupta, A., Kleinberg, J., Tardos, E., Wexler, T., & Roughgarden, T. (2008). The price of stability for network design with fair cost allocation. SIAM Journal on Computing, 38(4), 1602–1623.
Armbruster, A., Gosnell, M., McMillin, B., & Crow, M. L. (2005). Power transmission control using distributed max-flow. In Computer software and applications conference, 2005. COMPSAC 2005. 29th annual international, vol. 1, pp. 256–263. IEEE.
Cheung, T. Y. (1983). Graph traversal techniques and the maximum flow problem in distributed computation. IEEE Transactions on Software Engineering, 4, 504–512.
Cormen, T. H., Leiserson, C. E., Rivest, R. L., & Stein, C. (2009). Introduction to algorithms. Cambridge: MIT Press.
Dinic, E. A. (1970). Algorithm for solution of a problem of maximum flow in a network with power estimation. Soviet Mathematics Doklady, 11(5), 1277–1280. (English translation by RF. Rinehart).
Edmonds, J., & Karp, R. M. (1972). Theoretical improvements in algorithmic efficiency for network flow problems. Journal of the ACM, 19(2), 248–264.
Even, S., Itai, A., & Shamir, A. (1976). On the complexity of timetable and multicommodity flow problems. SIAM Journal on Computing, 5(4), 691–703.
Feigenbaum, J., Papadimitriou, C. H., Sami, R., & Shenker, S. (2005). A BGP-based mechanism for lowest-cost routing. Distributed Computing, 18(1), 61–72.
Ford, L. R., & Fulkerson, D. R. (1956). Maximal flow through a network. Canadian Journal of Mathematics, 8(3), 399–404.
Ford, L. R., & Fulkerson, D. R. (1962). Flows in networks. Princeton: Princeton University Press.
Goldberg, A. V., Tardos, É., & Tarjan, R. E. (1989). Network flow algorithms. Technical report, DTIC Document.
Goldberg, A. V., & Tarjan, R. E. (1988). A new approach to the maximum-flow problem. Journal of the ACM, 35(4), 921–940.
Kalai, E., & Zemel, E. (1982). Totally balanced games and games of flow. Mathematics of Operations Research, 7(3), 476–478.
Koutsoupias, E., & Papadimitriou, C. (2009). Worst-case equilibria. Computer Science Review, 3(2), 65–69.
Kupferman, O., Vardi, G., & Vardi, M. Y. (2017). Flow games. In Proceedings of 37th conference on foundations of software technology and theoretical computer science, vol. 93 of Leibniz international proceedings in informatics (LIPIcs), pp. 38:38–38:16.
Lichtenstein, O., & Pnueli, A. (1985). Checking that finite state concurrent programs satisfy their linear specification. In Proceedings of 12th ACM symposium on principles of programming languages, pp. 97–107.
Nash, J. F. (1950). Equilibrium points in n-person games. In Proceedings of the National Academy of Sciences of the USA.
Nisan, N., Roughgarden, T., Tardos, E., & Vazirani, V. V. (2007). Algorithmic game theory. Cambridge: Cambridge University Press.
Papadimitriou, C. H. (2001). Algorithms, games, and the internet. In Proceedings of 33rd ACM symposium on theory of computing, pp. 749–753.
Pnueli, A., & Rosner, R. (1989). On the synthesis of a reactive module. In Proceedings of 16th ACM symposium on principles of programming languages, pp. 179–190.
Tardos, É. (1985). A strongly polynomial minimum cost circulation algorithm. Combinatorica, 5(3), 247–255.
Vissicchio, S., Vanbever, L., & Bonaventure, O. (2014). Opportunities and research challenges of hybrid software defined networks. Computer Communication Review, 44(2), 70–75.
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A preliminary version has appeared in the 17th International Conference on Autonomous Agents and Multi-Agent Systems.
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Guha, S., Kupferman, O. & Vardi, G. Multi-player flow games. Auton Agent Multi-Agent Syst 33, 798–820 (2019). https://doi.org/10.1007/s10458-019-09420-2
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DOI: https://doi.org/10.1007/s10458-019-09420-2