Abstract
Markov decision processes (MDPs) are standard models for probabilistic systems with non-deterministic behaviours. Mean payoff (or long-run average reward) provides a mathematically elegant formalism to express performance related properties. Strategy iteration is one of the solution techniques applicable in this context. While in many other contexts it is the technique of choice due to advantages over e.g. value iteration, such as precision or possibility of domain-knowledge-aware initialization, it is rarely used for MDPs, since there it scales worse than value iteration. We provide several techniques that speed up strategy iteration by orders of magnitude for many MDPs, eliminating the performance disadvantage while preserving all its advantages.
This work is partially supported by the German Research Foundation (DFG) project “Verified Model Checkers” and the Czech Science Foundation grant No. 15-17564S.
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Notes
- 1.
The usual procedure of achieving this in general is to replace \( Act \) by \(S\times Act \) and adapting \(\mathsf {Av}\), \(\varDelta \), and \(r\) appropriately.
- 2.
Some authors deliberately exclude so called “trivial” or “transient” SCCs, which are single states without a self-loop.
- 3.
The \(\liminf \) is used since the limit may not exist in general for an arbitrary strategy.
- 4.
Note that the procedure found in [34, Sect. 9.2.1] differs from our Algorithm in Line 6. There, the bias is improved over all available actions instead of the gain-optimal ones, which is erroneous. The proofs provided in the corresponding chapter actually prove the correctness of the algorithm as presented here.
- 5.
On crafted models with less than 10 states we observed numerical errors leading to non-convergence and condition numbers of up to \(10^5\).
- 6.
Restricting a general MDP to a MEC results in a “communicating” MDP.
- 7.
We will go into detail why we do not deal with bias later on.
- 8.
Accessible at https://www7.in.tum.de/~meggendo/artifacts/2017/atva_si.txt.
- 9.
References
Abate, A., Češka, M., Kwiatkowska, M.: Approximate policy iteration for Markov Decision Processes via quantitative adaptive aggregations. In: Artho, C., Legay, A., Peled, D. (eds.) ATVA 2016. LNCS, vol. 9938, pp. 13–31. Springer, Cham (2016). doi:10.1007/978-3-319-46520-3_2
Ashok, P., Chatterjee, K., Daca, P., Křetínský, J., Meggendorfer, T.: Value iteration for long-run average reward in Markov Decision Processes. In: CAV (2017). To appear
Baier, C., Katoen, J.-P.: Principles of Model Checking (2008)
Baier, C., Klein, J., Leuschner, L., Parker, D., Wunderlich, S.: Ensuring the reliability of your model checker: Interval iteration for Markov Decision Processes. In: CAV (2017). To appear
Bertsekas, D.P.: Approximate policy iteration: a survey and some new methods. J. Control Theor. Appl. 9(3), 310–335 (2011)
Björklund, H., Vorobyov, S.G.: A combinatorial strongly subexponential strategy improvement algorithm for mean payoff games. DAM 155(2), 210–229 (2007)
Brázdil, T., Chatterjee, K., Chmelík, M., Forejt, V., Křetínský, J., Kwiatkowska, M., Parker, D., Ujma, M.: Verification of Markov Decision Processes using learning algorithms. In: Cassez, F., Raskin, J.-F. (eds.) ATVA 2014. LNCS, vol. 8837, pp. 98–114. Springer, Cham (2014). doi:10.1007/978-3-319-11936-6_8
Brázdil, T., Chatterjee, K., Forejt, V., Kučera, A.: MultiGain: a controller synthesis tool for MDPs with multiple mean-payoff objectives. In: Baier, C., Tinelli, C. (eds.) TACAS 2015. LNCS, vol. 9035, pp. 181–187. Springer, Heidelberg (2015). doi:10.1007/978-3-662-46681-0_12
Brim, L., Chaloupka, J.: Using strategy improvement to stay alive. IJCSIS 23(3), 585–608 (2012)
Chatterjee, K., Henzinger, T.: Value iteration. 25 Years of Model Checking, pp. 107–138 (2008)
Condon, A.: On algorithms for simple stochastic games. In: Advances in Computational Complexity Theory, pp. 51–72 (1990)
Courcoubetis, C., Yannakakis, M.: The complexity of probabilistic verification. J. ACM 42(4), 857–907 (1995)
de Alfaro, L.: Formal verification of probabilistic systems. Ph.D thesis (1997)
Duflot, M., Fribourg, L., Picaronny, C.: Randomized dining philosophers without fairness assumption. Distrib. Comput. 17(1), 65–76 (2004)
Fearnley, J.: Exponential lower bounds for policy iteration. In: Abramsky, S., Gavoille, C., Kirchner, C., Meyer auf der Heide, F., Spirakis, P.G. (eds.) ICALP 2010. LNCS, vol. 6199, pp. 551–562. Springer, Heidelberg (2010). doi:10.1007/978-3-642-14162-1_46
Fearnley, J.: Strategy iteration algorithms for games and Markov Decision Processes. Ph.D thesis, University of Warwick (2010)
Fearnley, J.: Efficient parallel strategy improvement for parity games. In: CAV (2017). To appear
Feng, L., Kwiatkowska, M., Parker, D.: Automated learning of probabilistic assumptions for compositional reasoning. In: Giannakopoulou, D., Orejas, F. (eds.) FASE 2011. LNCS, vol. 6603, pp. 2–17. Springer, Heidelberg (2011). doi:10.1007/978-3-642-19811-3_2
Filar, J., Vrieze, K.: Competitive Markov Decision Processes. Springer, New York (1997)
Frausto-Solis, J., Santiago, E., Mora-Vargas, J.: Cosine policy iteration for solving infinite-horizon Markov Decision Processes. In: Aguirre, A.H., Borja, R.M., Garciá, C.A.R. (eds.) MICAI 2009. LNCS, vol. 5845, pp. 75–86. Springer, Heidelberg (2009). doi:10.1007/978-3-642-05258-3_7
Friedmann, O.: An exponential lower bound for the parity game strategy improvement algorithm as we know it. In: LICS, pp. 145–156 (2009)
Gawlitza, T.M., Schwarz, M.D., Seidl, H.: Parametric strategy iteration. arXiv preprint arXiv:1406.5457 (2014)
Haddad, S., Monmege, B.: Reachability in MDPs: refining convergence of value iteration. In: Ouaknine, J., Potapov, I., Worrell, J. (eds.) RP 2014. LNCS, vol. 8762, pp. 125–137. Springer, Cham (2014). doi:10.1007/978-3-319-11439-2_10
Hahn, E.M., Schewe, S., Turrini, A., Zhang, L.: Synthesising strategy improvement and recursive algorithms for solving 2.5 player parity games. In: Bouajjani, A., Monniaux, D. (eds.) VMCAI 2017. LNCS, vol. 10145, pp. 266–287. Springer, Cham (2017). doi:10.1007/978-3-319-52234-0_15
Hansen, K.A., Ibsen-Jensen, R., Miltersen, P.B.: The complexity of solving reachability games using value and strategy iteration. Theor. Comput. Syst. 55(2), 380–403 (2014)
Hansen, T.D., Miltersen, P.B., Zwick, U.: Strategy iteration is strongly polynomial for 2-player turn-based stochastic games with a constant discount factor. J. ACM 60(1), 1:1–1:16 (2013)
Hordijk, A., Puterman, M.L.: On the convergence of policy iteration in finite state undiscounted Markov Decision Processes: the unichain case. MMOR 12(1), 163–176 (1987)
Howard, R.A.: Dynamic Programming and Markov Processes (1960)
Komuravelli, A., Păsăreanu, C.S., Clarke, E.M.: Assume-guarantee abstraction refinement for probabilistic systems. In: Madhusudan, P., Seshia, S.A. (eds.) CAV 2012. LNCS, vol. 7358, pp. 310–326. Springer, Heidelberg (2012). doi:10.1007/978-3-642-31424-7_25
Křetínský, J., Meggendorfer, T.: Efficient strategy iteration for mean payoff in Markov Decision Processes. Technical report abs/1707.01859. arXiv.org (2017)
Kwiatkowska, M., Norman, G., Parker, D.: PRISM 4.0: verification of probabilistic real-time systems. In: Gopalakrishnan, G., Qadeer, S. (eds.) CAV 2011. LNCS, vol. 6806, pp. 585–591. Springer, Heidelberg (2011). doi:10.1007/978-3-642-22110-1_47
Kwiatkowska, M., Norman, G., Parker, D., Vigliotti, M.G.: Probabilistic mobile ambients. Theoret. Comput. Sci. 410(12–13), 1272–1303 (2009)
Luttenberger, M.: Strategy iteration using non-deterministic strategies for solving parity games. CoRR, abs/0806.2923 (2008)
Puterman, M.L.: Markov Decision Processes: Discrete Stochastic Dynamic Programming. Wiley (2014)
Schewe, S.: An optimal strategy improvement algorithm for solving parity and payoff games. In: Kaminski, M., Martini, S. (eds.) CSL 2008. LNCS, vol. 5213, pp. 369–384. Springer, Heidelberg (2008). doi:10.1007/978-3-540-87531-4_27
Shlakhter, O., Lee, C.-G.: Accelerated modified policy iteration algorithms for Markov Decision Processes. MMOR 78(1), 61–76 (2013)
Tarjan, R.: Depth-first search and linear graph algorithms. SICOMP 1(2), 146–160 (1972)
Vöge, J., Jurdziński, M.: A discrete strategy improvement algorithm for solving parity games. In: Emerson, E.A., Sistla, A.P. (eds.) CAV 2000. LNCS, vol. 1855, pp. 202–215. Springer, Heidelberg (2000). doi:10.1007/10722167_18
Ye, Y.: The simplex and policy-iteration methods are strongly polynomial for the Markov decision problem with a fixed discount rate. MMOR 36(4), 593–603 (2011)
Acknowledgments
We thank the anonymous reviewers for their insightful comments and valuable suggestions. In particular, a considerable improvement to the BSCC compression approach of Sect. 4.2 has been proposed.
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Křetínský, J., Meggendorfer, T. (2017). Efficient Strategy Iteration for Mean Payoff in Markov Decision Processes. In: D'Souza, D., Narayan Kumar, K. (eds) Automated Technology for Verification and Analysis. ATVA 2017. Lecture Notes in Computer Science(), vol 10482. Springer, Cham. https://doi.org/10.1007/978-3-319-68167-2_25
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