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Habilitation à Diriger des Recherches

Law and partial order

Nonsequential behaviour and probability
asynchronous systems

Stefan Haar - projet DistribCom

Irisa - 30 octobre 2008

A major part of the presentation focuses on partial order behavior of Petri net-type systems. Petri net unfoldings are shown as natural and efficiently exploitable representations of such behaviour, in particular for asynchronous fault diagnosis in large networks. One strives to extract from a formal system model those partially ordered executions that provide the possible explanations for an observed pattern of visible alarms, under partial observability of the system events. The computation of the unfolding for the synchronized product of the observation with the system model solves the general asynchronous diagnosis problem; this leads to several extensions:

1) Analysis of diagnosability over Net unfoldings
2) Extension beyond Petri net models to evolving topologies, captured by Graph Grammars
3) Probabilistic analysis of unfoldings to determine the likelihood of a partially ordered run
4) Distributed computation of unfoldings for large systems with several local supervisors.

Further, the talk presents work done in the broader context of distributed systems, namely Troughput analysis in Free-Choice nets using transition blocking, and QoS in compositions of Web services and in heterogeneous networks.

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