35 Search Results for "Kupferman, Orna"


Document
Games with Trading of Control

Authors: Orna Kupferman and Noam Shenwald

Published in: LIPIcs, Volume 279, 34th International Conference on Concurrency Theory (CONCUR 2023)


Abstract
The interaction among components in a system is traditionally modeled by a game. In the turned-based setting, the players in the game jointly move a token along the game graph, with each player deciding where to move the token in vertices she controls. The objectives of the players are modeled by ω-regular winning conditions, and players whose objectives are satisfied get rewards. Thus, the game is non-zero-sum, and we are interested in its stable outcomes. In particular, in the rational-synthesis problem, we seek a strategy for the system player that guarantees the satisfaction of the system’s objective in all rational environments. In this paper, we study an extension of the traditional setting by trading of control. In our game, the players may pay each other in exchange for directing the token also in vertices they do not control. The utility of each player then combines the reward for the satisfaction of her objective and the profit from the trading. The setting combines challenges from ω-regular graph games with challenges in pricing, bidding, and auctions in classical game theory. We study the theoretical properties of parity trading games: best-response dynamics, existence and search for Nash equilibria, and measures for equilibrium inefficiency. We also study the rational-synthesis problem and analyze its tight complexity in various settings.

Cite as

Orna Kupferman and Noam Shenwald. Games with Trading of Control. In 34th International Conference on Concurrency Theory (CONCUR 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 279, pp. 19:1-19:17, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)


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@InProceedings{kupferman_et_al:LIPIcs.CONCUR.2023.19,
  author =	{Kupferman, Orna and Shenwald, Noam},
  title =	{{Games with Trading of Control}},
  booktitle =	{34th International Conference on Concurrency Theory (CONCUR 2023)},
  pages =	{19:1--19:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-299-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{279},
  editor =	{P\'{e}rez, Guillermo A. and Raskin, Jean-Fran\c{c}ois},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2023.19},
  URN =		{urn:nbn:de:0030-drops-190137},
  doi =		{10.4230/LIPIcs.CONCUR.2023.19},
  annote =	{Keywords: Parity Games, Rational Synthesis, Game Theory, Auctions}
}
Document
Track B: Automata, Logic, Semantics, and Theory of Programming
On Semantically-Deterministic Automata

Authors: Bader Abu Radi and Orna Kupferman

Published in: LIPIcs, Volume 261, 50th International Colloquium on Automata, Languages, and Programming (ICALP 2023)


Abstract
Nondeterminism is a fundamental notion in Theoretical Computer Science. A nondeterministic automaton is semantically deterministic (SD) if different nondeterministic choices in the automaton lead to equivalent states. Semantic determinism is interesting as it is a natural relaxation of determinism, and as some applications of automata in formal methods require deterministic automata, yet in fact can use automata with some level of nondeterminism, tightly related to semantic determinism. In the context of finite words, semantic determinism coincides with determinism, in the sense that every pruning of an SD automaton to a deterministic one results in an equivalent automaton. We study SD automata on infinite words, focusing on Büchi, co-Büchi, and weak automata. We show that there, while semantic determinism does not increase the expressive power, the combinatorial and computational properties of SD automata are very different from these of deterministic automata. In particular, SD Büchi and co-Büchi automata are exponentially more succinct than deterministic ones (in fact, also exponentially more succinct than history-deterministic automata), their complementation involves an exponential blow up, and decision procedures for them like universality and minimization are PSPACE-complete. For weak automata, we show that while an SD weak automaton need not be pruned to an equivalent deterministic one, it can be determinized to an equivalent deterministic weak automaton with the same state space, implying also efficient complementation and decision procedures for SD weak automata.

Cite as

Bader Abu Radi and Orna Kupferman. On Semantically-Deterministic Automata. In 50th International Colloquium on Automata, Languages, and Programming (ICALP 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 261, pp. 109:1-109:20, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)


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@InProceedings{aburadi_et_al:LIPIcs.ICALP.2023.109,
  author =	{Abu Radi, Bader and Kupferman, Orna},
  title =	{{On Semantically-Deterministic Automata}},
  booktitle =	{50th International Colloquium on Automata, Languages, and Programming (ICALP 2023)},
  pages =	{109:1--109:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-278-5},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{261},
  editor =	{Etessami, Kousha and Feige, Uriel and Puppis, Gabriele},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2023.109},
  URN =		{urn:nbn:de:0030-drops-181610},
  doi =		{10.4230/LIPIcs.ICALP.2023.109},
  annote =	{Keywords: Automata on infinite words, Nondeterminism, Succinctness, Decision procedures}
}
Document
Synthesis of Privacy-Preserving Systems

Authors: Orna Kupferman and Ofer Leshkowitz

Published in: LIPIcs, Volume 250, 42nd IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2022)


Abstract
Synthesis is the automated construction of a system from its specification. In many cases, we want to maintain the privacy of the system and the environment, thus limit the information that they share with each other or with an observer of the interaction. We introduce a framework for synthesis that addresses privacy in a simple yet powerful way. Our method is based on specification formalisms that include an unknown truth value. When the system and the environment interact, they may keep the truth values of some input and output signals private, which may cause the satisfaction value of specifications to become unknown. The input to the synthesis problem contains, in addition to the specification φ, also secrets ψ_1,…,ψ_k. During the interaction, the system directs the environment which input signals should stay private. The system then realizes the specification if in all interactions, the satisfaction value of the specification φ is true, whereas the satisfaction value of the secrets ψ_1,…,ψ_k is unknown. Thus, the specification is satisfied without the secrets being revealed. We describe our framework for specifications and secrets in LTL, and extend the framework also to the multi-valued specification formalism LTL[F], which enables the specification of the quality of computations. When both the specification and secrets are in LTL[F], one can trade-off the satisfaction value of the specification with the extent to which the satisfaction values of the secrets are revealed. We show that the complexity of the problem in all settings is 2EXPTIME-complete, thus it is not harder than synthesis with no privacy requirements.

Cite as

Orna Kupferman and Ofer Leshkowitz. Synthesis of Privacy-Preserving Systems. In 42nd IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 250, pp. 42:1-42:23, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2022)


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@InProceedings{kupferman_et_al:LIPIcs.FSTTCS.2022.42,
  author =	{Kupferman, Orna and Leshkowitz, Ofer},
  title =	{{Synthesis of Privacy-Preserving Systems}},
  booktitle =	{42nd IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2022)},
  pages =	{42:1--42:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-261-7},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{250},
  editor =	{Dawar, Anuj and Guruswami, Venkatesan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2022.42},
  URN =		{urn:nbn:de:0030-drops-174342},
  doi =		{10.4230/LIPIcs.FSTTCS.2022.42},
  annote =	{Keywords: Synthesis, Privacy, LTL, Games}
}
Document
Invited Paper
CONCUR Test-Of-Time Award 2022 (Invited Paper)

Authors: Ilaria Castellani, Paul Gastin, Orna Kupferman, Mickael Randour, and Davide Sangiorgi

Published in: LIPIcs, Volume 243, 33rd International Conference on Concurrency Theory (CONCUR 2022)


Abstract
This short article recaps the purpose of the CONCUR Test-of-Time Award and presents the four papers that received the Award in 2022.

Cite as

Ilaria Castellani, Paul Gastin, Orna Kupferman, Mickael Randour, and Davide Sangiorgi. CONCUR Test-Of-Time Award 2022 (Invited Paper). In 33rd International Conference on Concurrency Theory (CONCUR 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 243, pp. 1:1-1:3, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2022)


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@InProceedings{castellani_et_al:LIPIcs.CONCUR.2022.1,
  author =	{Castellani, Ilaria and Gastin, Paul and Kupferman, Orna and Randour, Mickael and Sangiorgi, Davide},
  title =	{{CONCUR Test-Of-Time Award 2022}},
  booktitle =	{33rd International Conference on Concurrency Theory (CONCUR 2022)},
  pages =	{1:1--1:3},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-246-4},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{243},
  editor =	{Klin, Bartek and Lasota, S{\l}awomir and Muscholl, Anca},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2022.1},
  URN =		{urn:nbn:de:0030-drops-170644},
  doi =		{10.4230/LIPIcs.CONCUR.2022.1},
  annote =	{Keywords: CONCUR Test-of-Time Award}
}
Document
Energy Games with Resource-Bounded Environments

Authors: Orna Kupferman and Naama Shamash Halevy

Published in: LIPIcs, Volume 243, 33rd International Conference on Concurrency Theory (CONCUR 2022)


Abstract
An energy game is played between two players, modeling a resource-bounded system and its environment. The players take turns moving a token along a finite graph. Each edge of the graph is labeled by an integer, describing an update to the energy level of the system that occurs whenever the edge is traversed. The system wins the game if it never runs out of energy. Different applications have led to extensions of the above basic setting. For example, addressing a combination of the energy requirement with behavioral specifications, researchers have studied richer winning conditions, and addressing systems with several bounded resources, researchers have studied games with multi-dimensional energy updates. All extensions, however, assume that the environment has no bounded resources. We introduce and study both-bounded energy games (BBEGs), in which both the system and the environment have multi-dimensional energy bounds. In BBEGs, each edge in the game graph is labeled by two integer vectors, describing updates to the multi-dimensional energy levels of the system and the environment. A system wins a BBEG if it never runs out of energy or if its environment runs out of energy. We show that BBEGs are determined, and that the problem of determining the winner in a given BBEG is decidable iff both the system and the environment have energy vectors of dimension 1. We also study how restrictions on the memory of the system and/or the environment as well as upper bounds on their energy levels influence the winner and the complexity of the problem.

Cite as

Orna Kupferman and Naama Shamash Halevy. Energy Games with Resource-Bounded Environments. In 33rd International Conference on Concurrency Theory (CONCUR 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 243, pp. 19:1-19:23, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2022)


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@InProceedings{kupferman_et_al:LIPIcs.CONCUR.2022.19,
  author =	{Kupferman, Orna and Shamash Halevy, Naama},
  title =	{{Energy Games with Resource-Bounded Environments}},
  booktitle =	{33rd International Conference on Concurrency Theory (CONCUR 2022)},
  pages =	{19:1--19:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-246-4},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{243},
  editor =	{Klin, Bartek and Lasota, S{\l}awomir and Muscholl, Anca},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2022.19},
  URN =		{urn:nbn:de:0030-drops-170823},
  doi =		{10.4230/LIPIcs.CONCUR.2022.19},
  annote =	{Keywords: Energy Games, Infinite-State Systems, Decidability}
}
Document
On the Minimisation of Transition-Based Rabin Automata and the Chromatic Memory Requirements of Muller Conditions

Authors: Antonio Casares

Published in: LIPIcs, Volume 216, 30th EACSL Annual Conference on Computer Science Logic (CSL 2022)


Abstract
In this paper, we relate the problem of determining the chromatic memory requirements of Muller conditions with the minimisation of transition-based Rabin automata. Our first contribution is a proof of the NP-completeness of the minimisation of transition-based Rabin automata. Our second contribution concerns the memory requirements of games over graphs using Muller conditions. A memory structure is a finite state machine that implements a strategy and is updated after reading the edges of the game; the special case of chromatic memories being those structures whose update function only consider the colours of the edges. We prove that the minimal amount of chromatic memory required in games using a given Muller condition is exactly the size of a minimal Rabin automaton recognising this condition. Combining these two results, we deduce that finding the chromatic memory requirements of a Muller condition is NP-complete. This characterisation also allows us to prove that chromatic memories cannot be optimal in general, disproving a conjecture by Kopczyński.

Cite as

Antonio Casares. On the Minimisation of Transition-Based Rabin Automata and the Chromatic Memory Requirements of Muller Conditions. In 30th EACSL Annual Conference on Computer Science Logic (CSL 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 216, pp. 12:1-12:17, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2022)


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@InProceedings{casares:LIPIcs.CSL.2022.12,
  author =	{Casares, Antonio},
  title =	{{On the Minimisation of Transition-Based Rabin Automata and the Chromatic Memory Requirements of Muller Conditions}},
  booktitle =	{30th EACSL Annual Conference on Computer Science Logic (CSL 2022)},
  pages =	{12:1--12:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-218-1},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{216},
  editor =	{Manea, Florin and Simpson, Alex},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2022.12},
  URN =		{urn:nbn:de:0030-drops-157322},
  doi =		{10.4230/LIPIcs.CSL.2022.12},
  annote =	{Keywords: Automata on Infinite Words, Games on Graphs, Arena-Independent Memory, Complexity}
}
Document
A Hierarchy of Nondeterminism

Authors: Bader Abu Radi, Orna Kupferman, and Ofer Leshkowitz

Published in: LIPIcs, Volume 202, 46th International Symposium on Mathematical Foundations of Computer Science (MFCS 2021)


Abstract
We study three levels in a hierarchy of nondeterminism: A nondeterministic automaton A is determinizable by pruning (DBP) if we can obtain a deterministic automaton equivalent to A by removing some of its transitions. Then, A is good-for-games (GFG) if its nondeterministic choices can be resolved in a way that only depends on the past. Finally, A is semantically deterministic (SD) if different nondeterministic choices in A lead to equivalent states. Some applications of automata in formal methods require deterministic automata, yet in fact can use automata with some level of nondeterminism. For example, DBP automata are useful in the analysis of online algorithms, and GFG automata are useful in synthesis and control. For automata on finite words, the three levels in the hierarchy coincide. We study the hierarchy for Büchi, co-Büchi, and weak automata on infinite words. We show that the hierarchy is strict, study the expressive power of the different levels in it, as well as the complexity of deciding the membership of a language in a given level. Finally, we describe a probability-based analysis of the hierarchy, which relates the level of nondeterminism with the probability that a random run on a word in the language is accepting.

Cite as

Bader Abu Radi, Orna Kupferman, and Ofer Leshkowitz. A Hierarchy of Nondeterminism. In 46th International Symposium on Mathematical Foundations of Computer Science (MFCS 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 202, pp. 85:1-85:21, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2021)


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@InProceedings{aburadi_et_al:LIPIcs.MFCS.2021.85,
  author =	{Abu Radi, Bader and Kupferman, Orna and Leshkowitz, Ofer},
  title =	{{A Hierarchy of Nondeterminism}},
  booktitle =	{46th International Symposium on Mathematical Foundations of Computer Science (MFCS 2021)},
  pages =	{85:1--85:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-201-3},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{202},
  editor =	{Bonchi, Filippo and Puglisi, Simon J.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2021.85},
  URN =		{urn:nbn:de:0030-drops-145254},
  doi =		{10.4230/LIPIcs.MFCS.2021.85},
  annote =	{Keywords: Automata on Infinite Words, Expressive power, Complexity, Games}
}
Document
Perspective Games with Notifications

Authors: Orna Kupferman and Noam Shenwald

Published in: LIPIcs, Volume 182, 40th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2020)


Abstract
A reactive system has to satisfy its specification in all environments. Accordingly, design of correct reactive systems corresponds to the synthesis of winning strategies in games that model the interaction between the system and its environment. The game is played on a graph whose vertices are partitioned among the players. The players jointly generate a path in the graph, with each player deciding the successor vertex whenever the path reaches a vertex she owns. The objective of the system player is to force the computation induced by the generated infinite path to satisfy a given specification. The traditional way of modelling uncertainty in such games is observation-based. There, uncertainty is longitudinal: the players partially observe all vertices in the history. Recently, researchers introduced perspective games, where uncertainty is transverse: players fully observe the vertices they own and have no information about the behavior of the computation between visits in such vertices. We introduce and study perspective games with notifications: uncertainty is still transverse, yet a player may be notified about events that happen between visits in vertices she owns. We distinguish between structural notifications, for example about visits in some vertices, and behavioral notifications, for example about the computation exhibiting a certain behavior. We study the theoretic properties of perspective games with notifications, and the problem of deciding whether a player has a winning perspective strategy. Such a strategy depends only on the visible history, which consists of both visits in vertices the player owns and notifications during visits in other vertices. We show that the problem is EXPTIME-complete for objectives given by a deterministic or universal parity automaton over an alphabet that labels the vertices of the game, and notifications given by a deterministic satellite, and is 2EXPTIME-complete for LTL objectives. In all cases, the complexity in the size of the graph and the satellite is polynomial - exponentially easier than games with observation-based partial visibility. We also analyze the complexity of the problem for richer types of satellites.

Cite as

Orna Kupferman and Noam Shenwald. Perspective Games with Notifications. In 40th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 182, pp. 51:1-51:16, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2020)


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@InProceedings{kupferman_et_al:LIPIcs.FSTTCS.2020.51,
  author =	{Kupferman, Orna and Shenwald, Noam},
  title =	{{Perspective Games with Notifications}},
  booktitle =	{40th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2020)},
  pages =	{51:1--51:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-174-0},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{182},
  editor =	{Saxena, Nitin and Simon, Sunil},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2020.51},
  URN =		{urn:nbn:de:0030-drops-132928},
  doi =		{10.4230/LIPIcs.FSTTCS.2020.51},
  annote =	{Keywords: Games, Incomplete Information, Automata}
}
Document
Unary Prime Languages

Authors: Ismaël Jecker, Orna Kupferman, and Nicolas Mazzocchi

Published in: LIPIcs, Volume 170, 45th International Symposium on Mathematical Foundations of Computer Science (MFCS 2020)


Abstract
A regular language L of finite words is composite if there are regular languages L₁,L₂,…,L_t such that L = ⋂_{i = 1}^t L_i and the index (number of states in a minimal DFA) of every language L_i is strictly smaller than the index of L. Otherwise, L is prime. Primality of regular languages was introduced and studied in [O. Kupferman and J. Mosheiff, 2015], where the complexity of deciding the primality of the language of a given DFA was left open, with a doubly-exponential gap between the upper and lower bounds. We study primality for unary regular languages, namely regular languages with a singleton alphabet. A unary language corresponds to a subset of ℕ, making the study of unary prime languages closer to that of primality in number theory. We show that the setting of languages is richer. In particular, while every composite number is the product of two smaller numbers, the number t of languages necessary to decompose a composite unary language induces a strict hierarchy. In addition, a primality witness for a unary language L, namely a word that is not in L but is in all products of languages that contain L and have an index smaller than L’s, may be of exponential length. Still, we are able to characterize compositionality by structural properties of a DFA for L, leading to a LogSpace algorithm for primality checking of unary DFAs.

Cite as

Ismaël Jecker, Orna Kupferman, and Nicolas Mazzocchi. Unary Prime Languages. In 45th International Symposium on Mathematical Foundations of Computer Science (MFCS 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 170, pp. 51:1-51:12, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2020)


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@InProceedings{jecker_et_al:LIPIcs.MFCS.2020.51,
  author =	{Jecker, Isma\"{e}l and Kupferman, Orna and Mazzocchi, Nicolas},
  title =	{{Unary Prime Languages}},
  booktitle =	{45th International Symposium on Mathematical Foundations of Computer Science (MFCS 2020)},
  pages =	{51:1--51:12},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-159-7},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{170},
  editor =	{Esparza, Javier and Kr\'{a}l', Daniel},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2020.51},
  URN =		{urn:nbn:de:0030-drops-127177},
  doi =		{10.4230/LIPIcs.MFCS.2020.51},
  annote =	{Keywords: Deterministic Finite Automata (DFA), Regular Languages, Primality}
}
Document
On Repetition Languages

Authors: Orna Kupferman and Ofer Leshkowitz

Published in: LIPIcs, Volume 170, 45th International Symposium on Mathematical Foundations of Computer Science (MFCS 2020)


Abstract
A regular language R of finite words induces three repetition languages of infinite words: the language lim(R), which contains words with infinitely many prefixes in R, the language ∞ R, which contains words with infinitely many disjoint subwords in R, and the language R^ω, which contains infinite concatenations of words in R. Specifying behaviors, the three repetition languages provide three different ways of turning a specification of a finite behavior into an infinite one. We study the expressive power required for recognizing repetition languages, in particular whether they can always be recognized by a deterministic Büchi word automaton (DBW), the blow up in going from an automaton for R to automata for the repetition languages, and the complexity of related decision problems. For lim R and ∞ R, most of these problems have already been studied or are easy. We focus on R^ω. Its study involves some new and interesting results about additional repetition languages, in particular R^#, which contains exactly all words with unboundedly many concatenations of words in R. We show that R^ω is DBW-recognizable iff R^# is ω-regular iff R^# = R^ω, and there are languages for which these criteria do not hold. Thus, R^ω need not be DBW-recognizable. In addition, when exists, the construction of a DBW for R^ω may involve a 2^{O(n log n)} blow-up, and deciding whether R^ω is DBW-recognizable, for R given by a nondeterministic automaton, is PSPACE-complete. Finally, we lift the difference between R^# and R^ω to automata on finite words and study a variant of Büchi automata where a word is accepted if (possibly different) runs on it visit accepting states unboundedly many times.

Cite as

Orna Kupferman and Ofer Leshkowitz. On Repetition Languages. In 45th International Symposium on Mathematical Foundations of Computer Science (MFCS 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 170, pp. 59:1-59:14, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2020)


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@InProceedings{kupferman_et_al:LIPIcs.MFCS.2020.59,
  author =	{Kupferman, Orna and Leshkowitz, Ofer},
  title =	{{On Repetition Languages}},
  booktitle =	{45th International Symposium on Mathematical Foundations of Computer Science (MFCS 2020)},
  pages =	{59:1--59:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-159-7},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{170},
  editor =	{Esparza, Javier and Kr\'{a}l', Daniel},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2020.59},
  URN =		{urn:nbn:de:0030-drops-127268},
  doi =		{10.4230/LIPIcs.MFCS.2020.59},
  annote =	{Keywords: B\"{u}chi automata, Expressive power, Succinctness}
}
Document
Coverage and Vacuity in Network Formation Games

Authors: Gili Bielous and Orna Kupferman

Published in: LIPIcs, Volume 152, 28th EACSL Annual Conference on Computer Science Logic (CSL 2020)


Abstract
The frameworks of coverage and vacuity in formal verification analyze the effect of mutations applied to systems or their specifications. We adopt these notions to network formation games, analyzing the effect of a change in the cost of a resource. We consider two measures to be affected: the cost of the Social Optimum and extremums of costs of Nash Equilibria. Our results offer a formal framework to the effect of mutations in network formation games and include a complexity analysis of related decision problems. They also tighten the relation between algorithmic game theory and formal verification, suggesting refined definitions of coverage and vacuity for the latter.

Cite as

Gili Bielous and Orna Kupferman. Coverage and Vacuity in Network Formation Games. In 28th EACSL Annual Conference on Computer Science Logic (CSL 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 152, pp. 10:1-10:18, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2020)


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@InProceedings{bielous_et_al:LIPIcs.CSL.2020.10,
  author =	{Bielous, Gili and Kupferman, Orna},
  title =	{{Coverage and Vacuity in Network Formation Games}},
  booktitle =	{28th EACSL Annual Conference on Computer Science Logic (CSL 2020)},
  pages =	{10:1--10:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-132-0},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{152},
  editor =	{Fern\'{a}ndez, Maribel and Muscholl, Anca},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2020.10},
  URN =		{urn:nbn:de:0030-drops-116532},
  doi =		{10.4230/LIPIcs.CSL.2020.10},
  annote =	{Keywords: Network Formation Games, Vacuity, Coverage}
}
Document
Good for Games Automata: From Nondeterminism to Alternation

Authors: Udi Boker and Karoliina Lehtinen

Published in: LIPIcs, Volume 140, 30th International Conference on Concurrency Theory (CONCUR 2019)


Abstract
A word automaton recognizing a language L is good for games (GFG) if its composition with any game with winning condition L preserves the game’s winner. While all deterministic automata are GFG, some nondeterministic automata are not. There are various other properties that are used in the literature for defining that a nondeterministic automaton is GFG, including "history-deterministic", "compliant with some letter game", "good for trees", and "good for composition with other automata". The equivalence of these properties has not been formally shown. We generalize all of these definitions to alternating automata and show their equivalence. We further show that alternating GFG automata are as expressive as deterministic automata with the same acceptance conditions and indices. We then show that alternating GFG automata over finite words, and weak automata over infinite words, are not more succinct than deterministic automata, and that determinizing Büchi and co-Büchi alternating GFG automata involves a 2^{Theta(n)} state blow-up. We leave open the question of whether alternating GFG automata of stronger acceptance conditions allow for doubly-exponential succinctness compared to deterministic automata.

Cite as

Udi Boker and Karoliina Lehtinen. Good for Games Automata: From Nondeterminism to Alternation. In 30th International Conference on Concurrency Theory (CONCUR 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 140, pp. 19:1-19:16, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2019)


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@InProceedings{boker_et_al:LIPIcs.CONCUR.2019.19,
  author =	{Boker, Udi and Lehtinen, Karoliina},
  title =	{{Good for Games Automata: From Nondeterminism to Alternation}},
  booktitle =	{30th International Conference on Concurrency Theory (CONCUR 2019)},
  pages =	{19:1--19:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-121-4},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{140},
  editor =	{Fokkink, Wan and van Glabbeek, Rob},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2019.19},
  URN =		{urn:nbn:de:0030-drops-109212},
  doi =		{10.4230/LIPIcs.CONCUR.2019.19},
  annote =	{Keywords: Good for games, history-determinism, alternation}
}
Document
Register-Bounded Synthesis

Authors: Ayrat Khalimov and Orna Kupferman

Published in: LIPIcs, Volume 140, 30th International Conference on Concurrency Theory (CONCUR 2019)


Abstract
Traditional synthesis algorithms return, given a specification over finite sets of input and output Boolean variables, a finite-state transducer all whose computations satisfy the specification. Many real-life systems have an infinite state space. In particular, behaviors of systems with a finite control yet variables that range over infinite domains, are specified by automata with infinite alphabets. A register automaton has a finite set of registers, and its transitions are based on a comparison of the letters in the input with these stored in its registers. Unfortunately, reasoning about register automata is complex. In particular, the synthesis problem for specifications given by register automata, where the goal is to generate correct register transducers, is undecidable. We study the synthesis problem for systems with a bounded number of registers. Formally, the register-bounded realizability problem is to decide, given a specification register automaton A over infinite input and output alphabets and numbers k_s and k_e of registers, whether there is a system transducer T with at most k_s registers such that for all environment transducers T' with at most k_e registers, the computation T|T', generated by the interaction of T with T', satisfies the specification A. The register-bounded synthesis problem is to construct such a transducer T, if exists. The bounded setting captures better real-life scenarios where bounds on the systems and/or its environment are known. In addition, the bounds are the key to new synthesis algorithms, and, as recently shown in [A. Khalimov et al., 2018], they lead to decidability. Our contributions include a stronger specification formalism (universal register parity automata), simpler algorithms, which enable a clean complexity analysis, a study of settings in which both the system and the environment are bounded, and a study of the theoretical aspects of the setting; in particular, the differences among a fixed, finite, and infinite number of registers, and the determinacy of the corresponding games.

Cite as

Ayrat Khalimov and Orna Kupferman. Register-Bounded Synthesis. In 30th International Conference on Concurrency Theory (CONCUR 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 140, pp. 25:1-25:16, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2019)


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@InProceedings{khalimov_et_al:LIPIcs.CONCUR.2019.25,
  author =	{Khalimov, Ayrat and Kupferman, Orna},
  title =	{{Register-Bounded Synthesis}},
  booktitle =	{30th International Conference on Concurrency Theory (CONCUR 2019)},
  pages =	{25:1--25:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-121-4},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{140},
  editor =	{Fokkink, Wan and van Glabbeek, Rob},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2019.25},
  URN =		{urn:nbn:de:0030-drops-109277},
  doi =		{10.4230/LIPIcs.CONCUR.2019.25},
  annote =	{Keywords: Synthesis, Register Automata, Register Transducers}
}
Document
Track B: Automata, Logic, Semantics, and Theory of Programming
Minimizing GFG Transition-Based Automata (Track B: Automata, Logic, Semantics, and Theory of Programming)

Authors: Bader Abu Radi and Orna Kupferman

Published in: LIPIcs, Volume 132, 46th International Colloquium on Automata, Languages, and Programming (ICALP 2019)


Abstract
While many applications of automata in formal methods can use nondeterministic automata, some applications, most notably synthesis, need deterministic or good-for-games automata. The latter are nondeterministic automata that can resolve their nondeterministic choices in a way that only depends on the past. The minimization problem for nondeterministic and deterministic Büchi and co-Büchi word automata are PSPACE-complete and NP-complete, respectively. We describe a polynomial minimization algorithm for good-for-games co-Büchi word automata with transition-based acceptance. Thus, a run is accepting if it traverses a set of designated transitions only finitely often. Our algorithm is based on a sequence of transformations we apply to the automaton, on top of which a minimal quotient automaton is defined.

Cite as

Bader Abu Radi and Orna Kupferman. Minimizing GFG Transition-Based Automata (Track B: Automata, Logic, Semantics, and Theory of Programming). In 46th International Colloquium on Automata, Languages, and Programming (ICALP 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 132, pp. 100:1-100:16, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2019)


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@InProceedings{aburadi_et_al:LIPIcs.ICALP.2019.100,
  author =	{Abu Radi, Bader and Kupferman, Orna},
  title =	{{Minimizing GFG Transition-Based Automata}},
  booktitle =	{46th International Colloquium on Automata, Languages, and Programming (ICALP 2019)},
  pages =	{100:1--100:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-109-2},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{132},
  editor =	{Baier, Christel and Chatzigiannakis, Ioannis and Flocchini, Paola and Leonardi, Stefano},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2019.100},
  URN =		{urn:nbn:de:0030-drops-106761},
  doi =		{10.4230/LIPIcs.ICALP.2019.100},
  annote =	{Keywords: Minimization, Deterministic co-B\"{u}chi Automata}
}
Document
Timed Network Games with Clocks

Authors: Guy Avni, Shibashis Guha, and Orna Kupferman

Published in: LIPIcs, Volume 117, 43rd International Symposium on Mathematical Foundations of Computer Science (MFCS 2018)


Abstract
Network games are widely used as a model for selfish resource-allocation problems. In the classical model, each player selects a path connecting her source and target vertices. The cost of traversing an edge depends on the load; namely, number of players that traverse it. Thus, it abstracts the fact that different users may use a resource at different times and for different durations, which plays an important role in determining the costs of the users in reality. For example, when transmitting packets in a communication network, routing traffic in a road network, or processing a task in a production system, actual sharing and congestion of resources crucially depends on time. In [G. Avni et al., 2017], we introduced timed network games, which add a time component to network games. Each vertex v in the network is associated with a cost function, mapping the load on v to the price that a player pays for staying in v for one time unit with this load. Each edge in the network is guarded by the time intervals in which it can be traversed, which forces the players to spend time in the vertices. In this work we significantly extend the way time can be referred to in timed network games. In the model we study, the network is equipped with clocks, and, as in timed automata, edges are guarded by constraints on the values of the clocks, and their traversal may involve a reset of some clocks. We argue that the stronger model captures many realistic networks. The addition of clocks breaks the techniques we developed in [G. Avni et al., 2017] and we develop new techniques in order to show that positive results on classic network games carry over to the stronger timed setting.

Cite as

Guy Avni, Shibashis Guha, and Orna Kupferman. Timed Network Games with Clocks. In 43rd International Symposium on Mathematical Foundations of Computer Science (MFCS 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 117, pp. 23:1-23:18, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2018)


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@InProceedings{avni_et_al:LIPIcs.MFCS.2018.23,
  author =	{Avni, Guy and Guha, Shibashis and Kupferman, Orna},
  title =	{{Timed Network Games with Clocks}},
  booktitle =	{43rd International Symposium on Mathematical Foundations of Computer Science (MFCS 2018)},
  pages =	{23:1--23:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-086-6},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{117},
  editor =	{Potapov, Igor and Spirakis, Paul and Worrell, James},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2018.23},
  URN =		{urn:nbn:de:0030-drops-96053},
  doi =		{10.4230/LIPIcs.MFCS.2018.23},
  annote =	{Keywords: Network games, Timed automata, Nash equilibrium, Equilibrium inefficiency}
}
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