Liveness in Timed and Untimed Systems

Segala, Roberto; Gawlick, Rainer; Søgaard-Andersen, Jørgen F.; Lynch, Nancy

doi:10.1006/inco.1997.2671

Cited by 40 publications

(35 citation statements)

References 9 publications

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“…Let s ∈ R, with R ∩ T 2i = ∅, and R ∩ T j = ∅ for all 2 ≤ j < 2i. The result follows from Lemmas 16,17,18,19,and 20. ⊓ ⊔ Lemma 16.…”

Section: Proof Of Lemma 12mentioning

confidence: 85%

“…This setting places no syntactic restriction on the game structure, and gives both players equally powerful options for advancing time, but for a player to win, she must not be responsible for causing time to converge. It has been shown in [15] that this is equivalent to requiring that the players are restricted to the use of receptive strategies [3,19], which, while being required to not prevent time from diverging, are not required to ensure time divergence. More formally, our timed games proceed in an infinite sequence of rounds.…”

Section: Introductionmentioning

confidence: 99%

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Trading Infinite Memory for Uniform Randomness in Timed Games

Chatterjee¹,

Henzinger²,

Prabhu³

Hybrid Systems: Computation and Control

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Abstract. We consider concurrent two-player timed automaton games with ω-regular objectives specified as parity conditions. These games offer an appropriate model for the synthesis of real-time controllers. Earlier works on timed games focused on pure strategies for each player. We study, for the first time, the use of randomized strategies in such games. While pure (i.e., nonrandomized) strategies in timed games require infinite memory for winning even with respect to reachability objectives, we show that randomized strategies can win with finite memory with respect to all parity objectives. Also, the synthesized randomized real-time controllers are much simpler in structure than the corresponding pure controllers, and therefore easier to implement. For safety objectives we prove the existence of pure finite-memory winning strategies. Finally, while randomization helps in simplifying the strategies required for winning timed parity games, we prove that randomization does not help in winning at more states.

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“…Let s ∈ R, with R ∩ T 2i = ∅, and R ∩ T j = ∅ for all 2 ≤ j < 2i. The result follows from Lemmas 16,17,18,19,and 20. ⊓ ⊔ Lemma 16.…”

Section: Proof Of Lemma 12mentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Trading Infinite Memory for Uniform Randomness in Timed Games

Chatterjee¹,

Henzinger²,

Prabhu³

Hybrid Systems: Computation and Control

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show abstract

“…‡ Since in our model we assume invocations and responses with unique process identifiers, there is no invocation or response event which is associated with more than one process. Therefore, unlike [29,33], we use a simplified definition of composition when input and output actions, that are used for communication between components, are hidden by becoming internal actions.…”

Section: System Modelmentioning

confidence: 99%

“…The correctness of a distributed algorithm is expressed through safety and liveness properties [30,1,33,29]. These properties can be defined as sets of histories (traces).…”

Section: Introductionmentioning

confidence: 99%

Safety-Liveness Exclusion in Distributed Computing

Bushkov

Guerraoui

2015

Proceedings of the 2015 ACM Symposium on Principles of Distributed Computing

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The history of distributed computing is full of trade-offs between safety and liveness. For instance, one of the most celebrated results in the field, namely the impossibility of consensus in an asynchronous system basically says that we cannot devise an algorithm that deterministically ensures consensus agreement and validity (i.e., safety) on the one hand, and consensus wait-freedom (i.e., liveness) on the other hand.The motivation of this work is to study the extent to which safety and liveness properties inherently exclude each other. More specifically, we ask, given any safety property S, whether we can determine the strongest (resp. weakest) liveness property that can (resp. cannot) be achieved with S. We show that, maybe surprisingly, the answers to these safety-liveness exclusion questions are in general negative. This has several ramifications in various distributed computing contexts. In the context of consensus for example, this means that it is impossible to determine the strongest (resp. the weakest) liveness property that can (resp. cannot) be ensured with linearizability.However, we present a way to circumvent these impossibilities and answer positively the safetyliveness question by considering a restricted form of liveness. We consider a definition that gathers generalized forms of obstruction-freedom and lock-freedom while enabling to determine the strongest (resp. weakest) liveness property that can (resp. cannot) be implemented in the context of consensus and transactional memory.

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“…Recently, [16] defined a variant of TADs where actions are distinguished between input and output following the model of [23] and for which bisimulation is a congruence for the parallel composition. This is possible due to input enabledness and to the fact that only output actions are allowed to be urgent (i.e.…”

Section: Introductionmentioning

confidence: 99%

The Coarsest Congruence for Timed Automata with Deadlines Contained in Bisimulation

D’Argenio

Gebremichael

2005

Lecture Notes in Computer Science

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Abstract. Delaying the synchronisation of actions may reveal some hidden behaviour that would not happen if the synchronisation would meet the specified deadlines. This precise phenomenon makes bisimulation fail to be a congruence for the parallel composition of timed automata with deadlines, a variant of timed automata where time progress is controlled by deadlines imposed on each transition. This problem has been known and unsolved for several years. In this paper we give a characterisation of the coarsest congruence that is included in the bisimulation relation. In addition, a symbolic characterisation of such relation is provided and shown to be decidable. We also discuss the pitfalls of existing parallel compositions in this setting and argue that our definition is both reasonable and sufficiently expressive as to consider the modelling of both soft and hard real-time constraints.

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Liveness in Timed and Untimed Systems

Cited by 40 publications

References 9 publications

Trading Infinite Memory for Uniform Randomness in Timed Games

Trading Infinite Memory for Uniform Randomness in Timed Games

Safety-Liveness Exclusion in Distributed Computing

The Coarsest Congruence for Timed Automata with Deadlines Contained in Bisimulation

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