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Documents authored by Hélouët, Loic

Found 2 Possible Name Variants:

Hélouët, Loic

Document
DOI: 10.4230/OASIcs.ATMOS.2024.16
Modeling Subway Networks and Passenger Flows

Authors: Antoine Thébault, Loïc Hélouët, and Kenza Saiah

Published in: OASIcs, Volume 123, 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)

Abstract
Simulation of urban rail networks provides useful information to optimize traffic management strategies w.r.t. goals such as satisfaction of passenger demands, adherence to schedules or energy saving. Many network models are too precise for the analysis needs, and do not exploit concurrency. This results in an explosion in the size of models, and long simulation times. This paper presents an extension of Petri nets that handles trajectories of trains, passenger flows, and scenarios for passenger arrivals. We then define a fast event-based simulation scheme. We test our model on a real case study, the Metro of Montreal, and show that full days of train operations with passengers can be simulated in a few seconds, allowing analysis of quantitative properties.
Cite as

Antoine Thébault, Loïc Hélouët, and Kenza Saiah. Modeling Subway Networks and Passenger Flows. In 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024). Open Access Series in Informatics (OASIcs), Volume 123, pp. 16:1-16:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{thebault_et_al:OASIcs.ATMOS.2024.16,
  author =	{Th\'{e}bault, Antoine and H\'{e}lou\"{e}t, Lo\"{i}c and Saiah, Kenza},
  title =	{{Modeling Subway Networks and Passenger Flows}},
  booktitle =	{24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)},
  pages =	{16:1--16:20},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-350-8},
  ISSN =	{2190-6807},
  year =	{2024},
  volume =	{123},
  editor =	{Bouman, Paul C. and Kontogiannis, Spyros C.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2024.16},
  URN =		{urn:nbn:de:0030-drops-212046},
  doi =		{10.4230/OASIcs.ATMOS.2024.16},
  annote =	{Keywords: Subways, Passenger Flows, Modelization, Petri-Nets, Trajectory-Nets}
}
Document
DOI: 10.4230/LIPIcs.FSTTCS.2021.33
Resilience of Timed Systems

Authors: S. Akshay, Blaise Genest, Loïc Hélouët, S. Krishna, and Sparsa Roychowdhury

Published in: LIPIcs, Volume 213, 41st IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2021)

Abstract
This paper addresses reliability of timed systems in the setting of resilience, that considers the behaviors of a system when unspecified timing errors such as missed deadlines occur. Given a fault model that allows transitions to fire later than allowed by their guard, a system is universally resilient (or self-resilient) if after a fault, it always returns to a timed behavior of the non-faulty system. It is existentially resilient if after a fault, there exists a way to return to a timed behavior of the non-faulty system, that is, if there exists a controller which can guide the system back to a normal behavior. We show that universal resilience of timed automata is undecidable, while existential resilience is decidable, in EXPSPACE. To obtain better complexity bounds and decidability of universal resilience, we consider untimed resilience, as well as subclasses of timed automata.
Cite as

S. Akshay, Blaise Genest, Loïc Hélouët, S. Krishna, and Sparsa Roychowdhury. Resilience of Timed Systems. In 41st IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 213, pp. 33:1-33:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@InProceedings{akshay_et_al:LIPIcs.FSTTCS.2021.33,
  author =	{Akshay, S. and Genest, Blaise and H\'{e}lou\"{e}t, Lo\"{i}c and Krishna, S. and Roychowdhury, Sparsa},
  title =	{{Resilience of Timed Systems}},
  booktitle =	{41st IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2021)},
  pages =	{33:1--33:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-215-0},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{213},
  editor =	{Boja\'{n}czyk, Miko{\l}aj and Chekuri, Chandra},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2021.33},
  URN =		{urn:nbn:de:0030-drops-155442},
  doi =		{10.4230/LIPIcs.FSTTCS.2021.33},
  annote =	{Keywords: Timed automata, Fault tolerance, Integer-resets, Resilience}
}
Document
DOI: 10.4230/LIPIcs.FSTTCS.2018.20
Hyper Partial Order Logic

Authors: Béatrice Bérard, Stefan Haar, and Loic Hélouët

Published in: LIPIcs, Volume 122, 38th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2018)

Abstract
We define HyPOL, a local hyper logic for partial order models, expressing properties of sets of runs. These properties depict shapes of causal dependencies in sets of partially ordered executions, with similarity relations defined as isomorphisms of past observations. Unsurprisingly, since comparison of projections are included, satisfiability of this logic is undecidable. We then address model checking of HyPOL and show that, already for safe Petri nets, the problem is undecidable. Fortunately, sensible restrictions of observations and nets allow us to bring back model checking of HyPOL to a decidable problem, namely model checking of MSO on graphs of bounded treewidth.
Cite as

Béatrice Bérard, Stefan Haar, and Loic Hélouët. Hyper Partial Order Logic. In 38th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 122, pp. 20:1-20:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)

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@InProceedings{berard_et_al:LIPIcs.FSTTCS.2018.20,
  author =	{B\'{e}rard, B\'{e}atrice and Haar, Stefan and H\'{e}lou\"{e}t, Loic},
  title =	{{Hyper Partial Order Logic}},
  booktitle =	{38th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2018)},
  pages =	{20:1--20:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-093-4},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{122},
  editor =	{Ganguly, Sumit and Pandya, Paritosh},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2018.20},
  URN =		{urn:nbn:de:0030-drops-99190},
  doi =		{10.4230/LIPIcs.FSTTCS.2018.20},
  annote =	{Keywords: Partial orders, logic, hyper-logic}
}

Hélouët, Loïc

Document
DOI: 10.4230/OASIcs.ATMOS.2024.16
Modeling Subway Networks and Passenger Flows

Authors: Antoine Thébault, Loïc Hélouët, and Kenza Saiah

Published in: OASIcs, Volume 123, 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)

Abstract
Simulation of urban rail networks provides useful information to optimize traffic management strategies w.r.t. goals such as satisfaction of passenger demands, adherence to schedules or energy saving. Many network models are too precise for the analysis needs, and do not exploit concurrency. This results in an explosion in the size of models, and long simulation times. This paper presents an extension of Petri nets that handles trajectories of trains, passenger flows, and scenarios for passenger arrivals. We then define a fast event-based simulation scheme. We test our model on a real case study, the Metro of Montreal, and show that full days of train operations with passengers can be simulated in a few seconds, allowing analysis of quantitative properties.
Cite as

Antoine Thébault, Loïc Hélouët, and Kenza Saiah. Modeling Subway Networks and Passenger Flows. In 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024). Open Access Series in Informatics (OASIcs), Volume 123, pp. 16:1-16:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

Copy BibTex To Clipboard

@InProceedings{thebault_et_al:OASIcs.ATMOS.2024.16,
  author =	{Th\'{e}bault, Antoine and H\'{e}lou\"{e}t, Lo\"{i}c and Saiah, Kenza},
  title =	{{Modeling Subway Networks and Passenger Flows}},
  booktitle =	{24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)},
  pages =	{16:1--16:20},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-350-8},
  ISSN =	{2190-6807},
  year =	{2024},
  volume =	{123},
  editor =	{Bouman, Paul C. and Kontogiannis, Spyros C.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2024.16},
  URN =		{urn:nbn:de:0030-drops-212046},
  doi =		{10.4230/OASIcs.ATMOS.2024.16},
  annote =	{Keywords: Subways, Passenger Flows, Modelization, Petri-Nets, Trajectory-Nets}
}
Document
DOI: 10.4230/LIPIcs.FSTTCS.2021.33
Resilience of Timed Systems

Authors: S. Akshay, Blaise Genest, Loïc Hélouët, S. Krishna, and Sparsa Roychowdhury

Published in: LIPIcs, Volume 213, 41st IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2021)

Abstract
This paper addresses reliability of timed systems in the setting of resilience, that considers the behaviors of a system when unspecified timing errors such as missed deadlines occur. Given a fault model that allows transitions to fire later than allowed by their guard, a system is universally resilient (or self-resilient) if after a fault, it always returns to a timed behavior of the non-faulty system. It is existentially resilient if after a fault, there exists a way to return to a timed behavior of the non-faulty system, that is, if there exists a controller which can guide the system back to a normal behavior. We show that universal resilience of timed automata is undecidable, while existential resilience is decidable, in EXPSPACE. To obtain better complexity bounds and decidability of universal resilience, we consider untimed resilience, as well as subclasses of timed automata.
Cite as

S. Akshay, Blaise Genest, Loïc Hélouët, S. Krishna, and Sparsa Roychowdhury. Resilience of Timed Systems. In 41st IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 213, pp. 33:1-33:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

Copy BibTex To Clipboard

@InProceedings{akshay_et_al:LIPIcs.FSTTCS.2021.33,
  author =	{Akshay, S. and Genest, Blaise and H\'{e}lou\"{e}t, Lo\"{i}c and Krishna, S. and Roychowdhury, Sparsa},
  title =	{{Resilience of Timed Systems}},
  booktitle =	{41st IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2021)},
  pages =	{33:1--33:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-215-0},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{213},
  editor =	{Boja\'{n}czyk, Miko{\l}aj and Chekuri, Chandra},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2021.33},
  URN =		{urn:nbn:de:0030-drops-155442},
  doi =		{10.4230/LIPIcs.FSTTCS.2021.33},
  annote =	{Keywords: Timed automata, Fault tolerance, Integer-resets, Resilience}
}
Document
DOI: 10.4230/LIPIcs.FSTTCS.2018.20
Hyper Partial Order Logic

Authors: Béatrice Bérard, Stefan Haar, and Loic Hélouët

Published in: LIPIcs, Volume 122, 38th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2018)

Abstract
We define HyPOL, a local hyper logic for partial order models, expressing properties of sets of runs. These properties depict shapes of causal dependencies in sets of partially ordered executions, with similarity relations defined as isomorphisms of past observations. Unsurprisingly, since comparison of projections are included, satisfiability of this logic is undecidable. We then address model checking of HyPOL and show that, already for safe Petri nets, the problem is undecidable. Fortunately, sensible restrictions of observations and nets allow us to bring back model checking of HyPOL to a decidable problem, namely model checking of MSO on graphs of bounded treewidth.
Cite as

Béatrice Bérard, Stefan Haar, and Loic Hélouët. Hyper Partial Order Logic. In 38th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 122, pp. 20:1-20:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)

Copy BibTex To Clipboard

@InProceedings{berard_et_al:LIPIcs.FSTTCS.2018.20,
  author =	{B\'{e}rard, B\'{e}atrice and Haar, Stefan and H\'{e}lou\"{e}t, Loic},
  title =	{{Hyper Partial Order Logic}},
  booktitle =	{38th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2018)},
  pages =	{20:1--20:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-093-4},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{122},
  editor =	{Ganguly, Sumit and Pandya, Paritosh},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2018.20},
  URN =		{urn:nbn:de:0030-drops-99190},
  doi =		{10.4230/LIPIcs.FSTTCS.2018.20},
  annote =	{Keywords: Partial orders, logic, hyper-logic}
}
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