11 Search Results for "Kozen, Dexter"


Document
Gorilla: Safe Permissionless Byzantine Consensus

Authors: Youer Pu, Ali Farahbakhsh, Lorenzo Alvisi, and Ittay Eyal

Published in: LIPIcs, Volume 281, 37th International Symposium on Distributed Computing (DISC 2023)


Abstract
Nakamoto’s consensus protocol works in a permissionless model and tolerates Byzantine failures, but only offers probabilistic agreement. Recently, the Sandglass protocol has shown such weaker guarantees are not a necessary consequence of a permissionless model; yet, Sandglass only tolerates benign failures, and operates in an unconventional partially synchronous model. We present Gorilla Sandglass, the first Byzantine tolerant consensus protocol to guarantee, in the same synchronous model adopted by Nakamoto, deterministic agreement and termination with probability 1 in a permissionless setting. We prove the correctness of Gorilla by mapping executions that would violate agreement or termination in Gorilla to executions in Sandglass, where we know such violations are impossible. Establishing termination proves particularly interesting, as the mapping requires reasoning about infinite executions and their probabilities.

Cite as

Youer Pu, Ali Farahbakhsh, Lorenzo Alvisi, and Ittay Eyal. Gorilla: Safe Permissionless Byzantine Consensus. In 37th International Symposium on Distributed Computing (DISC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 281, pp. 31:1-31:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{pu_et_al:LIPIcs.DISC.2023.31,
  author =	{Pu, Youer and Farahbakhsh, Ali and Alvisi, Lorenzo and Eyal, Ittay},
  title =	{{Gorilla: Safe Permissionless Byzantine Consensus}},
  booktitle =	{37th International Symposium on Distributed Computing (DISC 2023)},
  pages =	{31:1--31:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-301-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{281},
  editor =	{Oshman, Rotem},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2023.31},
  URN =		{urn:nbn:de:0030-drops-191579},
  doi =		{10.4230/LIPIcs.DISC.2023.31},
  annote =	{Keywords: Consensus, Permissionless, Blockchains, Byzantine fault tolerance, Deterministic Safety}
}
Document
Track B: Automata, Logic, Semantics, and Theory of Programming
Probabilistic Guarded KAT Modulo Bisimilarity: Completeness and Complexity

Authors: Wojciech Różowski, Tobias Kappé, Dexter Kozen, Todd Schmid, and Alexandra Silva

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


Abstract
We introduce Probabilistic Guarded Kleene Algebra with Tests (ProbGKAT), an extension of GKAT that allows reasoning about uninterpreted imperative programs with probabilistic branching. We give its operational semantics in terms of special class of probabilistic automata. We give a sound and complete Salomaa-style axiomatisation of bisimilarity of ProbGKAT expressions. Finally, we show that bisimilarity of ProbGKAT expressions can be decided in O(n³ log n) time via a generic partition refinement algorithm.

Cite as

Wojciech Różowski, Tobias Kappé, Dexter Kozen, Todd Schmid, and Alexandra Silva. Probabilistic Guarded KAT Modulo Bisimilarity: Completeness and Complexity. In 50th International Colloquium on Automata, Languages, and Programming (ICALP 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 261, pp. 136:1-136:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{rozowski_et_al:LIPIcs.ICALP.2023.136,
  author =	{R\'{o}\.{z}owski, Wojciech and Kapp\'{e}, Tobias and Kozen, Dexter and Schmid, Todd and Silva, Alexandra},
  title =	{{Probabilistic Guarded KAT Modulo Bisimilarity: Completeness and Complexity}},
  booktitle =	{50th International Colloquium on Automata, Languages, and Programming (ICALP 2023)},
  pages =	{136:1--136:20},
  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.2023.136},
  URN =		{urn:nbn:de:0030-drops-181880},
  doi =		{10.4230/LIPIcs.ICALP.2023.136},
  annote =	{Keywords: Kleene Algebra with Tests, program equivalence, completeness, coalgebra}
}
Document
Supported Sets - A New Foundation for Nominal Sets and Automata

Authors: Thorsten Wißmann

Published in: LIPIcs, Volume 252, 31st EACSL Annual Conference on Computer Science Logic (CSL 2023)


Abstract
The present work proposes and discusses the category of supported sets which provides a uniform foundation for nominal sets of various kinds, such as those for equality symmetry, for the order symmetry, and renaming sets. We show that all these differently flavoured categories of nominal sets are monadic over supported sets. Thus, supported sets provide a canonical finite way to represent nominal sets and the automata therein, e.g. register automata and coalgebras in general. Name binding in supported sets is modelled by a functor following the idea of de Bruijn indices. This functor lifts to the well-known abstraction functor in nominal sets. Together with the monadicity result, this gives rise to a transformation process from finite coalgebras in supported sets to orbit-finite coalgebras in nominal sets. One instance of this process transforms the finite representation of a register automaton in supported sets into its configuration automaton in nominal sets.

Cite as

Thorsten Wißmann. Supported Sets - A New Foundation for Nominal Sets and Automata. In 31st EACSL Annual Conference on Computer Science Logic (CSL 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 252, pp. 38:1-38:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{wimann:LIPIcs.CSL.2023.38,
  author =	{Wi{\ss}mann, Thorsten},
  title =	{{Supported Sets - A New Foundation for Nominal Sets and Automata}},
  booktitle =	{31st EACSL Annual Conference on Computer Science Logic (CSL 2023)},
  pages =	{38:1--38:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-264-8},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{252},
  editor =	{Klin, Bartek and Pimentel, Elaine},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2023.38},
  URN =		{urn:nbn:de:0030-drops-174992},
  doi =		{10.4230/LIPIcs.CSL.2023.38},
  annote =	{Keywords: Nominal Sets, Monads, LFP-Category, Supported Sets, Coalgebra}
}
Document
Track B: Automata, Logic, Semantics, and Theory of Programming
Guarded Kleene Algebra with Tests: Coequations, Coinduction, and Completeness

Authors: Todd Schmid, Tobias Kappé, Dexter Kozen, and Alexandra Silva

Published in: LIPIcs, Volume 198, 48th International Colloquium on Automata, Languages, and Programming (ICALP 2021)


Abstract
Guarded Kleene Algebra with Tests (GKAT) is an efficient fragment of KAT, as it allows for almost linear decidability of equivalence. In this paper, we study the (co)algebraic properties of GKAT. Our initial focus is on the fragment that can distinguish between unsuccessful programs performing different actions, by omitting the so-called early termination axiom. We develop an operational (coalgebraic) and denotational (algebraic) semantics and show that they coincide. We then characterize the behaviors of GKAT expressions in this semantics, leading to a coequation that captures the covariety of automata corresponding to these behaviors. Finally, we prove that the axioms of the reduced fragment are sound and complete w.r.t. the semantics, and then build on this result to recover a semantics that is sound and complete w.r.t. the full set of axioms.

Cite as

Todd Schmid, Tobias Kappé, Dexter Kozen, and Alexandra Silva. Guarded Kleene Algebra with Tests: Coequations, Coinduction, and Completeness. In 48th International Colloquium on Automata, Languages, and Programming (ICALP 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 198, pp. 142:1-142:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)


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@InProceedings{schmid_et_al:LIPIcs.ICALP.2021.142,
  author =	{Schmid, Todd and Kapp\'{e}, Tobias and Kozen, Dexter and Silva, Alexandra},
  title =	{{Guarded Kleene Algebra with Tests: Coequations, Coinduction, and Completeness}},
  booktitle =	{48th International Colloquium on Automata, Languages, and Programming (ICALP 2021)},
  pages =	{142:1--142:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-195-5},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{198},
  editor =	{Bansal, Nikhil and Merelli, Emanuela 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.ICALP.2021.142},
  URN =		{urn:nbn:de:0030-drops-142118},
  doi =		{10.4230/LIPIcs.ICALP.2021.142},
  annote =	{Keywords: Kleene algebra, program equivalence, completeness, coequations}
}
Document
Invited Talk
Guarded Kleene Algebra with Tests: Verification of Uninterpreted Programs in Nearly Linear Time (Invited Talk)

Authors: Alexandra Silva

Published in: LIPIcs, Volume 138, 44th International Symposium on Mathematical Foundations of Computer Science (MFCS 2019)


Abstract
Guarded Kleene Algebra with Tests (GKAT) is a variation on Kleene Algebra with Tests (KAT) that arises by restricting the union (+) and iteration (*) operations from KAT to predicate-guarded versions. We develop the (co)algebraic theory of GKAT and show how it can be efficiently used to reason about imperative programs. In contrast to KAT, whose equational theory is PSPACE-complete, we show that the equational theory of GKAT is (almost) linear time. We also provide a full Kleene theorem and prove completeness for an analogue of Salomaa’s axiomatization of Kleene Algebra. We will also discuss how this result has practical implications in the verification of programs, with examples from network and probabilistic programming. This is joint work with Nate Foster, Justin Hsu, Tobias Kappe, Dexter Kozen, and Steffen Smolka.

Cite as

Alexandra Silva. Guarded Kleene Algebra with Tests: Verification of Uninterpreted Programs in Nearly Linear Time (Invited Talk). In 44th International Symposium on Mathematical Foundations of Computer Science (MFCS 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 138, p. 2:1, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)


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@InProceedings{silva:LIPIcs.MFCS.2019.2,
  author =	{Silva, Alexandra},
  title =	{{Guarded Kleene Algebra with Tests: Verification of Uninterpreted Programs in Nearly Linear Time}},
  booktitle =	{44th International Symposium on Mathematical Foundations of Computer Science (MFCS 2019)},
  pages =	{2:1--2:1},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-117-7},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{138},
  editor =	{Rossmanith, Peter and Heggernes, Pinar and Katoen, Joost-Pieter},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2019.2},
  URN =		{urn:nbn:de:0030-drops-109462},
  doi =		{10.4230/LIPIcs.MFCS.2019.2},
  annote =	{Keywords: Kleene algebra, verification, decision procedures}
}
Document
The Ackermann Award 2018

Authors: Dexter Kozen and Thomas Schwentick

Published in: LIPIcs, Volume 119, 27th EACSL Annual Conference on Computer Science Logic (CSL 2018)


Abstract
The Ackermann Award is the EACSL Outstanding Dissertation Award for Logic in Computer Science. It is presented during the annual conference of the EACSL (CSL'xx). This contribution reports on the 2018 edition of the award.

Cite as

Dexter Kozen and Thomas Schwentick. The Ackermann Award 2018. In 27th EACSL Annual Conference on Computer Science Logic (CSL 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 119, pp. 1:1-1:5, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)


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@InProceedings{kozen_et_al:LIPIcs.CSL.2018.1,
  author =	{Kozen, Dexter and Schwentick, Thomas},
  title =	{{The Ackermann Award 2018}},
  booktitle =	{27th EACSL Annual Conference on Computer Science Logic (CSL 2018)},
  pages =	{1:1--1:5},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-088-0},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{119},
  editor =	{Ghica, Dan R. and Jung, Achim},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2018.1},
  URN =		{urn:nbn:de:0030-drops-96686},
  doi =		{10.4230/LIPIcs.CSL.2018.1},
  annote =	{Keywords: Ackermann Award}
}
Document
The Ackermann Award 2015

Authors: Anuj Dawar, Dexter Kozen, and Simona Ronchi Della Rocca

Published in: LIPIcs, Volume 41, 24th EACSL Annual Conference on Computer Science Logic (CSL 2015)


Abstract
The eleventh Ackermann Award is presented at CSL'15 in Berlin, Germany. This year, again, the EACSL Ackermann Award is generously sponsored by the Kurt Gödel Society. Besides providing financial support for the Ackermann Award, the Kurt Gödel Society has also committed to inviting the recipients of the Award for a special lecture to be given to the Society in Vienna.

Cite as

Anuj Dawar, Dexter Kozen, and Simona Ronchi Della Rocca. The Ackermann Award 2015. In 24th EACSL Annual Conference on Computer Science Logic (CSL 2015). Leibniz International Proceedings in Informatics (LIPIcs), Volume 41, pp. 15-18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2015)


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@InProceedings{dawar_et_al:LIPIcs.CSL.2015.xv,
  author =	{Dawar, Anuj and Kozen, Dexter and Ronchi Della Rocca, Simona},
  title =	{{The Ackermann Award 2015}},
  booktitle =	{24th EACSL Annual Conference on Computer Science Logic (CSL 2015)},
  pages =	{15--18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-90-3},
  ISSN =	{1868-8969},
  year =	{2015},
  volume =	{41},
  editor =	{Kreutzer, Stephan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2015.xv},
  URN =		{urn:nbn:de:0030-drops-54470},
  doi =		{10.4230/LIPIcs.CSL.2015.xv},
  annote =	{Keywords: Ackermann Award}
}
Document
Kleene Algebra with Products and Iteration Theories

Authors: Dexter Kozen and Konstantinos Mamouras

Published in: LIPIcs, Volume 23, Computer Science Logic 2013 (CSL 2013)


Abstract
We develop a typed equational system that subsumes both iteration theories and typed Kleene algebra in a common framework. Our approach is based on cartesian categories endowed with commutative strong monads to handle nondeterminism.

Cite as

Dexter Kozen and Konstantinos Mamouras. Kleene Algebra with Products and Iteration Theories. In Computer Science Logic 2013 (CSL 2013). Leibniz International Proceedings in Informatics (LIPIcs), Volume 23, pp. 415-431, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2013)


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@InProceedings{kozen_et_al:LIPIcs.CSL.2013.415,
  author =	{Kozen, Dexter and Mamouras, Konstantinos},
  title =	{{Kleene Algebra with Products and Iteration Theories}},
  booktitle =	{Computer Science Logic 2013 (CSL 2013)},
  pages =	{415--431},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-60-6},
  ISSN =	{1868-8969},
  year =	{2013},
  volume =	{23},
  editor =	{Ronchi Della Rocca, Simona},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2013.415},
  URN =		{urn:nbn:de:0030-drops-42111},
  doi =		{10.4230/LIPIcs.CSL.2013.415},
  annote =	{Keywords: Kleene algebra, typed Kleene algebra, iteration theories}
}
Document
Applications of Kleene Algebra (Dagstuhl Seminar 01081)

Authors: Roland C. Backhouse, Dexter Kozen, and Bernhard Möller

Published in: Dagstuhl Seminar Reports. Dagstuhl Seminar Reports, Volume 1 (2021)


Abstract

Cite as

Roland C. Backhouse, Dexter Kozen, and Bernhard Möller. Applications of Kleene Algebra (Dagstuhl Seminar 01081). Dagstuhl Seminar Report 298, pp. 1-21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2002)


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@TechReport{backhouse_et_al:DagSemRep.298,
  author =	{Backhouse, Roland C. and Kozen, Dexter and M\"{o}ller, Bernhard},
  title =	{{Applications of Kleene Algebra (Dagstuhl Seminar 01081)}},
  pages =	{1--21},
  ISSN =	{1619-0203},
  year =	{2002},
  type = 	{Dagstuhl Seminar Report},
  number =	{298},
  institution =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemRep.298},
  URN =		{urn:nbn:de:0030-drops-151829},
  doi =		{10.4230/DagSemRep.298},
}
Document
Applications of Tree Automata in Rewriting, Logic and Programming (Dagstuhl Seminar 9743)

Authors: Hubert Comon, Dexter Kozen, Helmut Seidl, and Mosche Y. Vardi

Published in: Dagstuhl Seminar Reports. Dagstuhl Seminar Reports, Volume 1 (2021)


Abstract

Cite as

Hubert Comon, Dexter Kozen, Helmut Seidl, and Mosche Y. Vardi. Applications of Tree Automata in Rewriting, Logic and Programming (Dagstuhl Seminar 9743). Dagstuhl Seminar Report 193, pp. 1-34, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (1997)


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@TechReport{comon_et_al:DagSemRep.193,
  author =	{Comon, Hubert and Kozen, Dexter and Seidl, Helmut and Vardi, Mosche Y.},
  title =	{{Applications of Tree Automata in Rewriting, Logic and Programming (Dagstuhl Seminar 9743)}},
  pages =	{1--34},
  ISSN =	{1619-0203},
  year =	{1997},
  type = 	{Dagstuhl Seminar Report},
  number =	{193},
  institution =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemRep.193},
  URN =		{urn:nbn:de:0030-drops-150792},
  doi =		{10.4230/DagSemRep.193},
}
Document
Algebraic Complexity and Parallelism (Dagstuhl Seminar 9230)

Authors: Joachim von zur Gathen, Marek Karpinski, and Dexter Kozen

Published in: Dagstuhl Seminar Reports. Dagstuhl Seminar Reports, Volume 1 (2021)


Abstract

Cite as

Joachim von zur Gathen, Marek Karpinski, and Dexter Kozen. Algebraic Complexity and Parallelism (Dagstuhl Seminar 9230). Dagstuhl Seminar Report 41, pp. 1-16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (1992)


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@TechReport{vonzurgathen_et_al:DagSemRep.41,
  author =	{von zur Gathen, Joachim and Karpinski, Marek and Kozen, Dexter},
  title =	{{Algebraic Complexity and Parallelism (Dagstuhl Seminar 9230)}},
  pages =	{1--16},
  ISSN =	{1619-0203},
  year =	{1992},
  type = 	{Dagstuhl Seminar Report},
  number =	{41},
  institution =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemRep.41},
  URN =		{urn:nbn:de:0030-drops-149291},
  doi =		{10.4230/DagSemRep.41},
}
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