Analysing Multi-Agent Systems using 1-safe Petri Nets

In the modelling and analysis of large, real systems, the main problem in their efficient processing is the size of the global model. One of the popular approaches that address this issue is the decomposition of such global model into much smaller submodels and interaction between them. In this paper we discuss the translation of multi-agent systems with the common-action-based synchronization to 1-safe Petri nets. We prove that the composition in terms of transition systems is equivalent to the transition-based fusion of nets modelling different agents. We also address the issue of permanent disabling of some parts of the system by constraints implied by the synchronization and discuss the methods of solving it without the computation of the entire global model.Comment: https://ceur-ws.org/Vol-3170/paper8.pd

A Finite Prefix for Analyzing Information Flow Among Transitions of a Free-Choice Net

In distributed systems, the occurrence of an action can give information about the occurrence of other actions. This can be an unwanted situation when 'high' actions of the system need to be kept secret, while allowing users to observe 'low' actions. If it is possible to deduce information about occurrence of high actions by observing only low actions, then the system suffers from an unwanted information flow. 'Reveals' and 'excludes' relations were introduced for modelling and analysing such an information flow among actions of a distributed system that is modelled via Petri nets. In this paper, we provide a formal basis for computing reveals and excludes relations of 1-safe free-choice Petri nets. We introduce the 'maximal-step computation tree' to represent the behaviour of a distributed system under maximal-step semantics. We define a finite prefix of the tree called 'full prefix' and we show that it is adequate for analysing information flow by means of reveals and excludes relations

Deux Opérations pour les Structures Stables de Régions Élémentaires

International audienc

Coexistence of Amyotrophic Lateral Sclerosis and Alzheimer's Disease : Case Report and Review of the Literature

We describe a case of amyotrophic lateral sclerosis (ALS) associated with Alzheimer's disease (AD) and review the literature about the coexistence of the two entities, highlighting the following: mean age at onset is 63.8 years, with slight female predominance; ALS tends to manifest after cognitive impairment and often begins in the bulbar region; average disease duration is 3 years; cognitive phenotype is mostly amnestic; the pattern of brain involvement is, in most cases, consistent with AD. Our case and the reviewed ones suggest that patients with ALS and dementia lacking unequivocal features of FTD should undergo additional examinations in order to recognize AD