59 Search Results for "Konnov, Igor"


Volume

LIPIcs, Volume 171

31st International Conference on Concurrency Theory (CONCUR 2020)

CONCUR 2020, September 1-4, 2020, Vienna, Austria (Virtual Conference)

Editors: Igor Konnov and Laura Kovács

Document
Holistic Verification of Blockchain Consensus

Authors: Nathalie Bertrand, Vincent Gramoli, Igor Konnov, Marijana Lazić, Pierre Tholoniat, and Josef Widder

Published in: LIPIcs, Volume 246, 36th International Symposium on Distributed Computing (DISC 2022)


Abstract
Blockchain has recently attracted the attention of the industry due, in part, to its ability to automate asset transfers. It requires distributed participants to reach a consensus on a block despite the presence of malicious (a.k.a. Byzantine) participants. Malicious participants exploit regularly weaknesses of these blockchain consensus algorithms, with sometimes devastating consequences. In fact, these weaknesses are quite common and are well illustrated by the flaws in various blockchain consensus algorithms [Pierre Tholoniat and Vincent Gramoli, 2019]. Paradoxically, until now, no blockchain consensus has been holistically verified. In this paper, we remedy this paradox by model checking for the first time a blockchain consensus used in industry. We propose a holistic approach to verify the consensus algorithm of the Red Belly Blockchain [Tyler Crain et al., 2021], for any number n of processes and any number f < n/3 of Byzantine processes. We decompose directly the algorithm pseudocode in two parts - an inner broadcast algorithm and an outer decision algorithm - each modelled as a threshold automaton [Igor Konnov et al., 2017], and we formalize their expected properties in linear-time temporal logic. We then automatically check the inner broadcasting algorithm, under a carefully identified fairness assumption. For the verification of the outer algorithm, we simplify the model of the inner algorithm by relying on its proven properties. Doing so, we formally verify, for any parameter, not only the safety properties of the Red Belly Blockchain consensus but also its liveness in less than 70 seconds.

Cite as

Nathalie Bertrand, Vincent Gramoli, Igor Konnov, Marijana Lazić, Pierre Tholoniat, and Josef Widder. Holistic Verification of Blockchain Consensus. In 36th International Symposium on Distributed Computing (DISC 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 246, pp. 10:1-10:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


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@InProceedings{bertrand_et_al:LIPIcs.DISC.2022.10,
  author =	{Bertrand, Nathalie and Gramoli, Vincent and Konnov, Igor and Lazi\'{c}, Marijana and Tholoniat, Pierre and Widder, Josef},
  title =	{{Holistic Verification of Blockchain Consensus}},
  booktitle =	{36th International Symposium on Distributed Computing (DISC 2022)},
  pages =	{10:1--10:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-255-6},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{246},
  editor =	{Scheideler, Christian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2022.10},
  URN =		{urn:nbn:de:0030-drops-172019},
  doi =		{10.4230/LIPIcs.DISC.2022.10},
  annote =	{Keywords: Model checking, automata, logic, byzantine failure}
}
Document
Short Paper
Formal Specification and Model Checking of the Tendermint Blockchain Synchronization Protocol (Short Paper)

Authors: Sean Braithwaite, Ethan Buchman, Igor Konnov, Zarko Milosevic, Ilina Stoilkovska, Josef Widder, and Anca Zamfir

Published in: OASIcs, Volume 84, 2nd Workshop on Formal Methods for Blockchains (FMBC 2020)


Abstract
Blockchain synchronization is one of the core protocols of Tendermint blockchains. In this short paper, we discuss our recent efforts in formal specification of the protocol and its implementation, as well as some initial model checking results. We demonstrate that the protocol quality and understanding can be improved by writing specifications and model checking them.

Cite as

Sean Braithwaite, Ethan Buchman, Igor Konnov, Zarko Milosevic, Ilina Stoilkovska, Josef Widder, and Anca Zamfir. Formal Specification and Model Checking of the Tendermint Blockchain Synchronization Protocol (Short Paper). In 2nd Workshop on Formal Methods for Blockchains (FMBC 2020). Open Access Series in Informatics (OASIcs), Volume 84, pp. 10:1-10:8, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{braithwaite_et_al:OASIcs.FMBC.2020.10,
  author =	{Braithwaite, Sean and Buchman, Ethan and Konnov, Igor and Milosevic, Zarko and Stoilkovska, Ilina and Widder, Josef and Zamfir, Anca},
  title =	{{Formal Specification and Model Checking of the Tendermint Blockchain Synchronization Protocol}},
  booktitle =	{2nd Workshop on Formal Methods for Blockchains (FMBC 2020)},
  pages =	{10:1--10:8},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-169-6},
  ISSN =	{2190-6807},
  year =	{2020},
  volume =	{84},
  editor =	{Bernardo, Bruno and Marmsoler, Diego},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.FMBC.2020.10},
  URN =		{urn:nbn:de:0030-drops-134238},
  doi =		{10.4230/OASIcs.FMBC.2020.10},
  annote =	{Keywords: Blockchain, Fault Tolerance, Byzantine Faults, Model Checking}
}
Document
Complete Volume
LIPIcs, Volume 171, CONCUR 2020, Complete Volume

Authors: Igor Konnov and Laura Kovács

Published in: LIPIcs, Volume 171, 31st International Conference on Concurrency Theory (CONCUR 2020)


Abstract
LIPIcs, Volume 171, CONCUR 2020, Complete Volume

Cite as

31st International Conference on Concurrency Theory (CONCUR 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 171, pp. 1-984, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@Proceedings{konnov_et_al:LIPIcs.CONCUR.2020,
  title =	{{LIPIcs, Volume 171, CONCUR 2020, Complete Volume}},
  booktitle =	{31st International Conference on Concurrency Theory (CONCUR 2020)},
  pages =	{1--984},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-160-3},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{171},
  editor =	{Konnov, Igor and Kov\'{a}cs, Laura},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2020},
  URN =		{urn:nbn:de:0030-drops-128115},
  doi =		{10.4230/LIPIcs.CONCUR.2020},
  annote =	{Keywords: LIPIcs, Volume 171, CONCUR 2020, Complete Volume}
}
Document
Front Matter
Front Matter, Table of Contents, Preface, Conference Organization

Authors: Igor Konnov and Laura Kovács

Published in: LIPIcs, Volume 171, 31st International Conference on Concurrency Theory (CONCUR 2020)


Abstract
Front Matter, Table of Contents, Preface, Conference Organization

Cite as

31st International Conference on Concurrency Theory (CONCUR 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 171, pp. 0:i-0:xvi, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{konnov_et_al:LIPIcs.CONCUR.2020.0,
  author =	{Konnov, Igor and Kov\'{a}cs, Laura},
  title =	{{Front Matter, Table of Contents, Preface, Conference Organization}},
  booktitle =	{31st International Conference on Concurrency Theory (CONCUR 2020)},
  pages =	{0:i--0:xvi},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-160-3},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{171},
  editor =	{Konnov, Igor and Kov\'{a}cs, Laura},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2020.0},
  URN =		{urn:nbn:de:0030-drops-128125},
  doi =		{10.4230/LIPIcs.CONCUR.2020.0},
  annote =	{Keywords: Front Matter, Table of Contents, Preface, Conference Organization}
}
Document
Invited Paper
On Privacy and Accuracy in Data Releases (Invited Paper)

Authors: Mário S. Alvim, Natasha Fernandes, Annabelle McIver, and Gabriel H. Nunes

Published in: LIPIcs, Volume 171, 31st International Conference on Concurrency Theory (CONCUR 2020)


Abstract
In this paper we study the relationship between privacy and accuracy in the context of correlated datasets. We use a model of quantitative information flow to describe the the trade-off between privacy of individuals' data and and the utility of queries to that data by modelling the effectiveness of adversaries attempting to make inferences after a data release. We show that, where correlations exist in datasets, it is not possible to implement optimal noise-adding mechanisms that give the best possible accuracy or the best possible privacy in all situations. Finally we illustrate the trade-off between accuracy and privacy for local and oblivious differentially private mechanisms in terms of inference attacks on medium-scale datasets.

Cite as

Mário S. Alvim, Natasha Fernandes, Annabelle McIver, and Gabriel H. Nunes. On Privacy and Accuracy in Data Releases (Invited Paper). In 31st International Conference on Concurrency Theory (CONCUR 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 171, pp. 1:1-1:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{alvim_et_al:LIPIcs.CONCUR.2020.1,
  author =	{Alvim, M\'{a}rio S. and Fernandes, Natasha and McIver, Annabelle and Nunes, Gabriel H.},
  title =	{{On Privacy and Accuracy in Data Releases}},
  booktitle =	{31st International Conference on Concurrency Theory (CONCUR 2020)},
  pages =	{1:1--1:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-160-3},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{171},
  editor =	{Konnov, Igor and Kov\'{a}cs, Laura},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2020.1},
  URN =		{urn:nbn:de:0030-drops-128130},
  doi =		{10.4230/LIPIcs.CONCUR.2020.1},
  annote =	{Keywords: Privacy/utility trade-off, Quantitative Information Flow, inference attacks}
}
Document
Invited Paper
A Survey of Bidding Games on Graphs (Invited Paper)

Authors: Guy Avni and Thomas A. Henzinger

Published in: LIPIcs, Volume 171, 31st International Conference on Concurrency Theory (CONCUR 2020)


Abstract
A graph game is a two-player zero-sum game in which the players move a token throughout a graph to produce an infinite path, which determines the winner or payoff of the game. In bidding games, both players have budgets, and in each turn, we hold an "auction" (bidding) to determine which player moves the token. In this survey, we consider several bidding mechanisms and study their effect on the properties of the game. Specifically, bidding games, and in particular bidding games of infinite duration, have an intriguing equivalence with random-turn games in which in each turn, the player who moves is chosen randomly. We show how minor changes in the bidding mechanism lead to unexpected differences in the equivalence with random-turn games.

Cite as

Guy Avni and Thomas A. Henzinger. A Survey of Bidding Games on Graphs (Invited Paper). In 31st International Conference on Concurrency Theory (CONCUR 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 171, pp. 2:1-2:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{avni_et_al:LIPIcs.CONCUR.2020.2,
  author =	{Avni, Guy and Henzinger, Thomas A.},
  title =	{{A Survey of Bidding Games on Graphs}},
  booktitle =	{31st International Conference on Concurrency Theory (CONCUR 2020)},
  pages =	{2:1--2:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-160-3},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{171},
  editor =	{Konnov, Igor and Kov\'{a}cs, Laura},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2020.2},
  URN =		{urn:nbn:de:0030-drops-128147},
  doi =		{10.4230/LIPIcs.CONCUR.2020.2},
  annote =	{Keywords: Bidding games, Richman bidding, poorman bidding, mean-payoff, parity}
}
Document
Invited Paper
Safe Reinforcement Learning Using Probabilistic Shields (Invited Paper)

Authors: Nils Jansen, Bettina Könighofer, Sebastian Junges, Alex Serban, and Roderick Bloem

Published in: LIPIcs, Volume 171, 31st International Conference on Concurrency Theory (CONCUR 2020)


Abstract
This paper concerns the efficient construction of a safety shield for reinforcement learning. We specifically target scenarios that incorporate uncertainty and use Markov decision processes (MDPs) as the underlying model to capture such problems. Reinforcement learning (RL) is a machine learning technique that can determine near-optimal policies in MDPs that may be unknown before exploring the model. However, during exploration, RL is prone to induce behavior that is undesirable or not allowed in safety- or mission-critical contexts. We introduce the concept of a probabilistic shield that enables RL decision-making to adhere to safety constraints with high probability. We employ formal verification to efficiently compute the probabilities of critical decisions within a safety-relevant fragment of the MDP. These results help to realize a shield that, when applied to an RL algorithm, restricts the agent from taking unsafe actions, while optimizing the performance objective. We discuss tradeoffs between sufficient progress in the exploration of the environment and ensuring safety. In our experiments, we demonstrate on the arcade game PAC-MAN and on a case study involving service robots that the learning efficiency increases as the learning needs orders of magnitude fewer episodes.

Cite as

Nils Jansen, Bettina Könighofer, Sebastian Junges, Alex Serban, and Roderick Bloem. Safe Reinforcement Learning Using Probabilistic Shields (Invited Paper). In 31st International Conference on Concurrency Theory (CONCUR 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 171, pp. 3:1-3:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{jansen_et_al:LIPIcs.CONCUR.2020.3,
  author =	{Jansen, Nils and K\"{o}nighofer, Bettina and Junges, Sebastian and Serban, Alex and Bloem, Roderick},
  title =	{{Safe Reinforcement Learning Using Probabilistic Shields}},
  booktitle =	{31st International Conference on Concurrency Theory (CONCUR 2020)},
  pages =	{3:1--3:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-160-3},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{171},
  editor =	{Konnov, Igor and Kov\'{a}cs, Laura},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2020.3},
  URN =		{urn:nbn:de:0030-drops-128155},
  doi =		{10.4230/LIPIcs.CONCUR.2020.3},
  annote =	{Keywords: Safe Reinforcement Learning, Formal Verification, Safe Exploration, Model Checking, Markov Decision Process}
}
Document
Invited Paper
Modern Applications of Game-Theoretic Principles (Invited Paper)

Authors: Catuscia Palamidessi and Marco Romanelli

Published in: LIPIcs, Volume 171, 31st International Conference on Concurrency Theory (CONCUR 2020)


Abstract
Game theory is the study of the strategic behavior of rational decision makers who are aware that their decisions affect one another. Its simple but universal principles have found applications in the most diverse disciplines, including economics, social sciences, evolutionary biology, as well as logic, system science and computer science. Despite its long-standing tradition and its many advances, game theory is still a young and developing science. In this paper, we describe some recent and exciting applications in the fields of machine learning and privacy.

Cite as

Catuscia Palamidessi and Marco Romanelli. Modern Applications of Game-Theoretic Principles (Invited Paper). In 31st International Conference on Concurrency Theory (CONCUR 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 171, pp. 4:1-4:9, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{palamidessi_et_al:LIPIcs.CONCUR.2020.4,
  author =	{Palamidessi, Catuscia and Romanelli, Marco},
  title =	{{Modern Applications of Game-Theoretic Principles}},
  booktitle =	{31st International Conference on Concurrency Theory (CONCUR 2020)},
  pages =	{4:1--4:9},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-160-3},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{171},
  editor =	{Konnov, Igor and Kov\'{a}cs, Laura},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2020.4},
  URN =		{urn:nbn:de:0030-drops-128167},
  doi =		{10.4230/LIPIcs.CONCUR.2020.4},
  annote =	{Keywords: Game theory, machine learning, privacy, security}
}
Document
Invited Paper
CONCUR Test-Of-Time Award 2020 Announcement (Invited Paper)

Authors: Luca Aceto, Jos Baeten, Patricia Bouyer-Decitre, Holger Hermanns, and Alexandra Silva

Published in: LIPIcs, Volume 171, 31st International Conference on Concurrency Theory (CONCUR 2020)


Abstract
This short article announces the recipients of the CONCUR Test-of-Time Award 2020.

Cite as

Luca Aceto, Jos Baeten, Patricia Bouyer-Decitre, Holger Hermanns, and Alexandra Silva. CONCUR Test-Of-Time Award 2020 Announcement (Invited Paper). In 31st International Conference on Concurrency Theory (CONCUR 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 171, pp. 5:1-5:3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{aceto_et_al:LIPIcs.CONCUR.2020.5,
  author =	{Aceto, Luca and Baeten, Jos and Bouyer-Decitre, Patricia and Hermanns, Holger and Silva, Alexandra},
  title =	{{CONCUR Test-Of-Time Award 2020 Announcement}},
  booktitle =	{31st International Conference on Concurrency Theory (CONCUR 2020)},
  pages =	{5:1--5:3},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-160-3},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{171},
  editor =	{Konnov, Igor and Kov\'{a}cs, Laura},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2020.5},
  URN =		{urn:nbn:de:0030-drops-128172},
  doi =		{10.4230/LIPIcs.CONCUR.2020.5},
  annote =	{Keywords: Concurrency, CONCUR Test-of-Time Award}
}
Document
Reactive Bisimulation Semantics for a Process Algebra with Time-Outs

Authors: Rob van Glabbeek

Published in: LIPIcs, Volume 171, 31st International Conference on Concurrency Theory (CONCUR 2020)


Abstract
This paper introduces the counterpart of strong bisimilarity for labelled transition systems extended with time-out transitions. It supports this concept through a modal characterisation, congruence results for a standard process algebra with recursion, and a complete axiomatisation.

Cite as

Rob van Glabbeek. Reactive Bisimulation Semantics for a Process Algebra with Time-Outs. In 31st International Conference on Concurrency Theory (CONCUR 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 171, pp. 6:1-6:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{vanglabbeek:LIPIcs.CONCUR.2020.6,
  author =	{van Glabbeek, Rob},
  title =	{{Reactive Bisimulation Semantics for a Process Algebra with Time-Outs}},
  booktitle =	{31st International Conference on Concurrency Theory (CONCUR 2020)},
  pages =	{6:1--6:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-160-3},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{171},
  editor =	{Konnov, Igor and Kov\'{a}cs, Laura},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2020.6},
  URN =		{urn:nbn:de:0030-drops-128181},
  doi =		{10.4230/LIPIcs.CONCUR.2020.6},
  annote =	{Keywords: Process algebra, time-outs, labelled transition systems, reactive bisimulation semantics, Hennessy-Milner logic, modal characterisations, recursion, complete axiomatisations}
}
Document
How Reversibility Can Solve Traditional Questions: The Example of Hereditary History-Preserving Bisimulation

Authors: Clément Aubert and Ioana Cristescu

Published in: LIPIcs, Volume 171, 31st International Conference on Concurrency Theory (CONCUR 2020)


Abstract
Reversible computation opens up the possibility of overcoming some of the hardware’s current physical limitations. It also offers theoretical insights, as it enriches multiple paradigms and models of computation, and sometimes retrospectively enlightens them. Concurrent reversible computation, for instance, offered interesting extensions to the Calculus of Communicating Systems, but was still lacking a natural and pertinent bisimulation to study processes equivalences. Our paper formulates an equivalence exploiting the two aspects of reversibility: backward moves and memory mechanisms. This bisimulation captures classical equivalences relations for denotational models of concurrency (history- and hereditary history-preserving bisimulation, (H)HPB), that were up to now only partially characterized by process algebras. This result gives an insight on the expressiveness of reversibility, as both backward moves and a memory mechanism - providing "backward determinism" - are needed to capture HHPB.

Cite as

Clément Aubert and Ioana Cristescu. How Reversibility Can Solve Traditional Questions: The Example of Hereditary History-Preserving Bisimulation. In 31st International Conference on Concurrency Theory (CONCUR 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 171, pp. 7:1-7:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{aubert_et_al:LIPIcs.CONCUR.2020.7,
  author =	{Aubert, Cl\'{e}ment and Cristescu, Ioana},
  title =	{{How Reversibility Can Solve Traditional Questions: The Example of Hereditary History-Preserving Bisimulation}},
  booktitle =	{31st International Conference on Concurrency Theory (CONCUR 2020)},
  pages =	{7:1--7:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-160-3},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{171},
  editor =	{Konnov, Igor and Kov\'{a}cs, Laura},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2020.7},
  URN =		{urn:nbn:de:0030-drops-128196},
  doi =		{10.4230/LIPIcs.CONCUR.2020.7},
  annote =	{Keywords: Formal semantics, Process algebras and calculi, Distributed and reversible computation, Configuration structures, Reversible CCS, Bisimulation}
}
Document
A Near-Linear-Time Algorithm for Weak Bisimilarity on Markov Chains

Authors: David N. Jansen, Jan Friso Groote, Ferry Timmers, and Pengfei Yang

Published in: LIPIcs, Volume 171, 31st International Conference on Concurrency Theory (CONCUR 2020)


Abstract
This article improves the time bound for calculating the weak/branching bisimulation minimisation quotient on state-labelled discrete-time Markov chains from O(m n) to an expected-time O(m log⁴ n), where n is the number of states and m the number of transitions. For these results we assume that the set of state labels AP is small (|AP| ∈ O(m/n log⁴ n)). It follows the ideas of Groote et al. (ACM ToCL 2017) in combination with an efficient algorithm to handle decremental strongly connected components (Bernstein et al., STOC 2019).

Cite as

David N. Jansen, Jan Friso Groote, Ferry Timmers, and Pengfei Yang. A Near-Linear-Time Algorithm for Weak Bisimilarity on Markov Chains. In 31st International Conference on Concurrency Theory (CONCUR 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 171, pp. 8:1-8:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{jansen_et_al:LIPIcs.CONCUR.2020.8,
  author =	{Jansen, David N. and Groote, Jan Friso and Timmers, Ferry and Yang, Pengfei},
  title =	{{A Near-Linear-Time Algorithm for Weak Bisimilarity on Markov Chains}},
  booktitle =	{31st International Conference on Concurrency Theory (CONCUR 2020)},
  pages =	{8:1--8:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-160-3},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{171},
  editor =	{Konnov, Igor and Kov\'{a}cs, Laura},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2020.8},
  URN =		{urn:nbn:de:0030-drops-128209},
  doi =		{10.4230/LIPIcs.CONCUR.2020.8},
  annote =	{Keywords: Behavioural Equivalence, weak Bisimulation, Markov Chain}
}
Document
Characterizing Consensus in the Heard-Of Model

Authors: A. R. Balasubramanian and Igor Walukiewicz

Published in: LIPIcs, Volume 171, 31st International Conference on Concurrency Theory (CONCUR 2020)


Abstract
The Heard-Of model is a simple and relatively expressive model of distributed computation. Because of this, it has gained a considerable attention of the verification community. We give a characterization of all algorithms solving consensus in a fragment of this model. The fragment is big enough to cover many prominent consensus algorithms. The characterization is purely syntactic: it is expressed in terms of some conditions on the text of the algorithm.

Cite as

A. R. Balasubramanian and Igor Walukiewicz. Characterizing Consensus in the Heard-Of Model. In 31st International Conference on Concurrency Theory (CONCUR 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 171, pp. 9:1-9:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


Copy BibTex To Clipboard

@InProceedings{balasubramanian_et_al:LIPIcs.CONCUR.2020.9,
  author =	{Balasubramanian, A. R. and Walukiewicz, Igor},
  title =	{{Characterizing Consensus in the Heard-Of Model}},
  booktitle =	{31st International Conference on Concurrency Theory (CONCUR 2020)},
  pages =	{9:1--9:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-160-3},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{171},
  editor =	{Konnov, Igor and Kov\'{a}cs, Laura},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2020.9},
  URN =		{urn:nbn:de:0030-drops-128217},
  doi =		{10.4230/LIPIcs.CONCUR.2020.9},
  annote =	{Keywords: consensus problem, Heard-Of model, verification}
}
Document
A Classification of Weak Asynchronous Models of Distributed Computing

Authors: Javier Esparza and Fabian Reiter

Published in: LIPIcs, Volume 171, 31st International Conference on Concurrency Theory (CONCUR 2020)


Abstract
We conduct a systematic study of asynchronous models of distributed computing consisting of identical finite-state devices that cooperate in a network to decide if the network satisfies a given graph-theoretical property. Models discussed in the literature differ in the detection capabilities of the agents residing at the nodes of the network (detecting the set of states of their neighbors, or counting the number of neighbors in each state), the notion of acceptance (acceptance by halting in a particular configuration, or by stable consensus), the notion of step (synchronous move, interleaving, or arbitrary timing), and the fairness assumptions (non-starving, or stochastic-like). We study the expressive power of the combinations of these features, and show that the initially twenty possible combinations fit into seven equivalence classes. The classification is the consequence of several equi-expressivity results with a clear interpretation. In particular, we show that acceptance by halting configuration only has non-trivial expressive power if it is combined with counting, and that synchronous and interleaving models have the same power as those in which an arbitrary set of nodes can move at the same time. We also identify simple graph properties that distinguish the expressive power of the seven classes.

Cite as

Javier Esparza and Fabian Reiter. A Classification of Weak Asynchronous Models of Distributed Computing. In 31st International Conference on Concurrency Theory (CONCUR 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 171, pp. 10:1-10:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


Copy BibTex To Clipboard

@InProceedings{esparza_et_al:LIPIcs.CONCUR.2020.10,
  author =	{Esparza, Javier and Reiter, Fabian},
  title =	{{A Classification of Weak Asynchronous Models of Distributed Computing}},
  booktitle =	{31st International Conference on Concurrency Theory (CONCUR 2020)},
  pages =	{10:1--10:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-160-3},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{171},
  editor =	{Konnov, Igor and Kov\'{a}cs, Laura},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2020.10},
  URN =		{urn:nbn:de:0030-drops-128229},
  doi =		{10.4230/LIPIcs.CONCUR.2020.10},
  annote =	{Keywords: Asynchrony, Concurrency theory, Weak models of distributed computing}
}
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