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Documents authored by Dantam, Mohan


Document
Mean-Payoff-Parity and Lifting Strategies from MDPs to 2-Player Stochastic Games

Authors: Mohan Dantam and Richard Mayr

Published in: LIPIcs, Volume 391, 37th International Conference on Concurrency Theory (CONCUR 2026)


Abstract
We consider the strategy complexity (i.e., memory and randomization) of optimal strategies in turn-based 2-player zero-sum stochastic games. Results in [Gimbert and Kelmendi, 2023; Richard Mayr et al., 2021] show how to lift optimal memoryless strategies for shift-invariant inverse-submixing objectives from MDPs to 2-player stochastic games with an exponential increase in the number of memory modes. We show the corresponding lower bound, i.e., the extra exponential memory is required in general, even for randomized strategies. Moreover, we solve the strategy complexity of the well-studied mean-payoff-parity objective (MP > 0 ∩ EPAR) in 2-player stochastic games. This objective is also shift-invariant inverse-submixing, but easier than the worst case for this class. In MDPs, Maximizer has optimal memoryless randomized strategies, while optimal deterministic strategies require exponential memory. However, in stochastic games, optimal randomized strategies require, at least and at most, linear memory (equal to the number of even colors). Finally, we show that the different construction in [Gimbert and Zielonka, 2009; Patricia Bouyer et al., 2023] for lifting memoryless (resp. finite-memory) deterministic strategies from MDPs (resp. 1-player games) to 2-player games cannot be generalized even to memoryless randomized strategies. We construct a shift-invariant objective where Max and Min each have optimal memoryless randomized strategies in all MDPs, but optimal (randomized) Max strategies still require infinite memory in deterministic 2-player games.

Cite as

Mohan Dantam and Richard Mayr. Mean-Payoff-Parity and Lifting Strategies from MDPs to 2-Player Stochastic Games. In 37th International Conference on Concurrency Theory (CONCUR 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 391, pp. 30:1-30:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)


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@InProceedings{dantam_et_al:LIPIcs.CONCUR.2026.30,
  author =	{Dantam, Mohan and Mayr, Richard},
  title =	{{Mean-Payoff-Parity and Lifting Strategies from MDPs to 2-Player Stochastic Games}},
  booktitle =	{37th International Conference on Concurrency Theory (CONCUR 2026)},
  pages =	{30:1--30:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-447-5},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{391},
  editor =	{Sokolova, Ana and Totzke, Patrick},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2026.30},
  URN =		{urn:nbn:de:0030-drops-273601},
  doi =		{10.4230/LIPIcs.CONCUR.2026.30},
  annote =	{Keywords: MDPs, Stochastic Games, Parity, Mean-payoff, Strategy complexity}
}
Document
Track B: Automata, Logic, Semantics, and Theory of Programming
Finite-Memory Strategies for Almost-Sure Energy-MeanPayoff Objectives in MDPs

Authors: Mohan Dantam and Richard Mayr

Published in: LIPIcs, Volume 297, 51st International Colloquium on Automata, Languages, and Programming (ICALP 2024)


Abstract
We consider finite-state Markov decision processes with the combined Energy-MeanPayoff objective. The controller tries to avoid running out of energy while simultaneously attaining a strictly positive mean payoff in a second dimension. We show that finite memory suffices for almost surely winning strategies for the Energy-MeanPayoff objective. This is in contrast to the closely related Energy-Parity objective, where almost surely winning strategies require infinite memory in general. We show that exponential memory is sufficient (even for deterministic strategies) and necessary (even for randomized strategies) for almost surely winning Energy-MeanPayoff. The upper bound holds even if the strictly positive mean payoff part of the objective is generalized to multidimensional strictly positive mean payoff. Finally, it is decidable in pseudo-polynomial time whether an almost surely winning strategy exists.

Cite as

Mohan Dantam and Richard Mayr. Finite-Memory Strategies for Almost-Sure Energy-MeanPayoff Objectives in MDPs. In 51st International Colloquium on Automata, Languages, and Programming (ICALP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 297, pp. 133:1-133:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{dantam_et_al:LIPIcs.ICALP.2024.133,
  author =	{Dantam, Mohan and Mayr, Richard},
  title =	{{Finite-Memory Strategies for Almost-Sure Energy-MeanPayoff Objectives in MDPs}},
  booktitle =	{51st International Colloquium on Automata, Languages, and Programming (ICALP 2024)},
  pages =	{133:1--133:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-322-5},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{297},
  editor =	{Bringmann, Karl and Grohe, Martin and Puppis, Gabriele and Svensson, Ola},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2024.133},
  URN =		{urn:nbn:de:0030-drops-202762},
  doi =		{10.4230/LIPIcs.ICALP.2024.133},
  annote =	{Keywords: Markov decision processes, energy, mean payoff, parity, strategy complexity}
}
Document
Approximating the Value of Energy-Parity Objectives in Simple Stochastic Games

Authors: Mohan Dantam and Richard Mayr

Published in: LIPIcs, Volume 272, 48th International Symposium on Mathematical Foundations of Computer Science (MFCS 2023)


Abstract
We consider simple stochastic games G with energy-parity objectives, a combination of quantitative rewards with a qualitative parity condition. The Maximizer tries to avoid running out of energy while simultaneously satisfying a parity condition. We present an algorithm to approximate the value of a given configuration in 2-NEXPTIME. Moreover, ε-optimal strategies for either player require at most O(2-EXP(|G|)⋅log(1/ε)) memory modes.

Cite as

Mohan Dantam and Richard Mayr. Approximating the Value of Energy-Parity Objectives in Simple Stochastic Games. In 48th International Symposium on Mathematical Foundations of Computer Science (MFCS 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 272, pp. 38:1-38:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{dantam_et_al:LIPIcs.MFCS.2023.38,
  author =	{Dantam, Mohan and Mayr, Richard},
  title =	{{Approximating the Value of Energy-Parity Objectives in Simple Stochastic Games}},
  booktitle =	{48th International Symposium on Mathematical Foundations of Computer Science (MFCS 2023)},
  pages =	{38:1--38:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-292-1},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{272},
  editor =	{Leroux, J\'{e}r\^{o}me and Lombardy, Sylvain and Peleg, David},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2023.38},
  URN =		{urn:nbn:de:0030-drops-185724},
  doi =		{10.4230/LIPIcs.MFCS.2023.38},
  annote =	{Keywords: Energy-Parity Games, Simple Stochastic Games, Parity, Energy}
}

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