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Papers by Christophe Morvan

Lecture Notes in Computer Science, 2011

Partial observation of discrete-event systems features a setting where events split into observab... more Partial observation of discrete-event systems features a setting where events split into observable and unobservable ones. In this context, the diagnosis of a discrete-event system consists in detecting defects from the (partial) observation of its executions. Diagnosability is the property that any defect is eventually detected. Not surprisingly, it is a major issue in practical applications. We investigate diagnosability for classes of pushdown systems: it is undecidable in general, but we exhibit reasonably large classes of visibly pushdown systems where the problem is decidable. For these classes, we furthermore prove the decidability of a stronger property: the bounded latency, which guarantees the existence of a uniform bound on the respond delay after the defect has occurred. We also explore a generalization of the approach to higher-order pushdown systems.

Lecture Notes in Computer Science, 2001

This paper shows that the traces of rational graphs coincide with the context-sensitive languages.

Electronic Proceedings in Theoretical Computer Science, 2010

... Probabilistic regular graphs Nathalie Bertrand INRIA Rennes Bretagne Atlantiquenathalie.bertr... more ... Probabilistic regular graphs Nathalie Bertrand INRIA Rennes Bretagne Atlantiquenathalie.bertrand@inria.fr ... Given h a hypergraph labelled by N ∪T, we denote by [H] the set of terminal arcs and colours in H: [H] = H ∩(T2 VH VH ∪T1 VH ). ...

Discrete Event Dynamic Systems, 2014

ABSTRACT The overall objective of project P22 is the analysis of the robustness and theimprovemen... more ABSTRACT The overall objective of project P22 is the analysis of the robustness and theimprovement of timetables and regulation techniques in urban railway systems.The project is expected to produce tools and models to evaluate and comparetimetables and regulation techniques that will serve as decision support duringearly phases of urban train systems conception.The project is divided into two phases : Phase 1 (ending in December 2014)will consist in a state of the art on regulation of urban rail systems, a preliminaryexploration of adapted formalisms to model urban train systems, timetablesand regulation algorithms, and a denition of objectives for the second phase.Phase 2 is expected to last up to 3 years, and will consist in a development ofthe techniques and directions dened during Phase 1.This document summarizes the expected contributions of the rst phase ofproject P22, and the use cases that will be used to validate the proposed ap-proaches: an existing metro network topology, typical examples of perturbationscenarios, and of regulation policies.

ABSTRACT This document is a focused state of the art for the P22 project between ALSTOMand the IN... more ABSTRACT This document is a focused state of the art for the P22 project between ALSTOMand the INRIA SUMO team. The goal of this project is to provideevaluation tools for the robustness of schedules (a.k.a timetables) for urbantrain systems, and evaluation techniques for regulation policies.

Lecture Notes in Computer Science, 2006

Rational graphs are a family of graphs defined using labelled rational transducers. Unlike automa... more Rational graphs are a family of graphs defined using labelled rational transducers. Unlike automatic graphs (defined using synchronized transducers) the first order theory of these graphs is undecidable, there is even a rational graph with an undecidable first order theory. In this paper we consider the family of rational trees, that is rational graphs which are trees. We prove that first order theory is decidable for this family. We also present counter examples showing that this result cannot be significantly extended both in terms of logic and of structure.

11th International Workshop on Discrete Event Systems, 2012

Logical Methods in Computer Science, 2012

We investigate the decidability and complexity status of model-checking problems on unlabelled re... more We investigate the decidability and complexity status of model-checking problems on unlabelled reachability graphs of Petri nets by considering first-order and modal languages without labels on transitions or atomic propositions on markings. We consider several parameters to separate decidable problems from undecidable ones. Not only are we able to provide precise borders and a systematic analysis, but we also demonstrate the robustness of our proof techniques.

Acta Informatica, 2005

In the hierarchy of infinite graph families, rational graphs are defined by rational transducers ... more In the hierarchy of infinite graph families, rational graphs are defined by rational transducers with labelled final states. This paper proves that their traces are precisely context-sensitive languages and that this result remains true for synchronized rational graphs.

Proceedings of the 30th Annual ACM Symposium on Applied Computing - SAC '15, 2015

Lecture Notes in Computer Science, 2011

Partial observation of discrete-event systems features a setting where events split into observab... more Partial observation of discrete-event systems features a setting where events split into observable and unobservable ones. In this context, the diagnosis of a discrete-event system consists in detecting defects from the (partial) observation of its executions. Diagnosability is the property that any defect is eventually detected. Not surprisingly, it is a major issue in practical applications. We investigate diagnosability for classes of pushdown systems: it is undecidable in general, but we exhibit reasonably large classes of visibly pushdown systems where the problem is decidable. For these classes, we furthermore prove the decidability of a stronger property: the bounded latency, which guarantees the existence of a uniform bound on the respond delay after the defect has occurred. We also explore a generalization of the approach to higher-order pushdown systems.

Lecture Notes in Computer Science, 2001

This paper shows that the traces of rational graphs coincide with the context-sensitive languages.

Electronic Proceedings in Theoretical Computer Science, 2010

... Probabilistic regular graphs Nathalie Bertrand INRIA Rennes Bretagne Atlantiquenathalie.bertr... more ... Probabilistic regular graphs Nathalie Bertrand INRIA Rennes Bretagne Atlantiquenathalie.bertrand@inria.fr ... Given h a hypergraph labelled by N ∪T, we denote by [H] the set of terminal arcs and colours in H: [H] = H ∩(T2 VH VH ∪T1 VH ). ...

Discrete Event Dynamic Systems, 2014

ABSTRACT The overall objective of project P22 is the analysis of the robustness and theimprovemen... more ABSTRACT The overall objective of project P22 is the analysis of the robustness and theimprovement of timetables and regulation techniques in urban railway systems.The project is expected to produce tools and models to evaluate and comparetimetables and regulation techniques that will serve as decision support duringearly phases of urban train systems conception.The project is divided into two phases : Phase 1 (ending in December 2014)will consist in a state of the art on regulation of urban rail systems, a preliminaryexploration of adapted formalisms to model urban train systems, timetablesand regulation algorithms, and a denition of objectives for the second phase.Phase 2 is expected to last up to 3 years, and will consist in a development ofthe techniques and directions dened during Phase 1.This document summarizes the expected contributions of the rst phase ofproject P22, and the use cases that will be used to validate the proposed ap-proaches: an existing metro network topology, typical examples of perturbationscenarios, and of regulation policies.

ABSTRACT This document is a focused state of the art for the P22 project between ALSTOMand the IN... more ABSTRACT This document is a focused state of the art for the P22 project between ALSTOMand the INRIA SUMO team. The goal of this project is to provideevaluation tools for the robustness of schedules (a.k.a timetables) for urbantrain systems, and evaluation techniques for regulation policies.

Lecture Notes in Computer Science, 2006

Rational graphs are a family of graphs defined using labelled rational transducers. Unlike automa... more Rational graphs are a family of graphs defined using labelled rational transducers. Unlike automatic graphs (defined using synchronized transducers) the first order theory of these graphs is undecidable, there is even a rational graph with an undecidable first order theory. In this paper we consider the family of rational trees, that is rational graphs which are trees. We prove that first order theory is decidable for this family. We also present counter examples showing that this result cannot be significantly extended both in terms of logic and of structure.

11th International Workshop on Discrete Event Systems, 2012

Logical Methods in Computer Science, 2012

We investigate the decidability and complexity status of model-checking problems on unlabelled re... more We investigate the decidability and complexity status of model-checking problems on unlabelled reachability graphs of Petri nets by considering first-order and modal languages without labels on transitions or atomic propositions on markings. We consider several parameters to separate decidable problems from undecidable ones. Not only are we able to provide precise borders and a systematic analysis, but we also demonstrate the robustness of our proof techniques.

Acta Informatica, 2005

In the hierarchy of infinite graph families, rational graphs are defined by rational transducers ... more In the hierarchy of infinite graph families, rational graphs are defined by rational transducers with labelled final states. This paper proves that their traces are precisely context-sensitive languages and that this result remains true for synchronized rational graphs.

Proceedings of the 30th Annual ACM Symposium on Applied Computing - SAC '15, 2015