Imposing Hierarchy on a Graph

This paper investigates a way of imposing a hierarchy on a graph in order to explore relationships between elements of data. Imposing a hierarchy is equivalent to clustering. First a tree structure is imposed on the initial graph, then a k-partite structure is imposed on each previously obtained cluster. Imposing a tree exposes the hierarchical structure of the graph as well as providing an abstraction of the data. In this study three kinds of merge operations are considered and their composition is shown to yield a tree with a maximal number of vertices in which vertices in the tree are associated with disjoint connected subgraphs. These subgraphs are subsequently transformed into k-partite graphs using similar merge operations. These merges also ensure that the obtained tree is proper with respect to the hierarchy imposed on the data. A detailed example of the techniqueâs application in exposing the structure of protein interaction networks is described. The example focuses on the MAPK cell signalling pathway. The merge operations help expose where signal regulation occurs within the pathway and from other signalling pathways within the cell

Da mi-carême ao carnabeach: história da(s) micareta(s)

Este artigo tem como propósito apresentar a história da micareta no Brasil, desde seu surgimento enquanto mi-carême até seus últimos desdobramentos atuais. A pesquisa se deu em parte sintetizando a escassa literatura relativa ao tema, mas a maioria das informações contidas neste artigo provêm de uma extensiva pesquisa de cunho histórico, em arquivos principalmente jornalísticos, de publicações cearenses, soteropolitanas e nacionais. A micareta aparece como uma festa bastante antiga (existindo desde 1908), com uma rica história intimamente ligada ao carnaval de Salvador e à evolução dos trios elétricos e das bandas de trios baianas. Correspondendo às sucessivas fases de expansão da festa pelo país, cinco etapas foram caracterizadas nessa evolução, cujo traço marcante foi o gradativo processo de comercialização sofridona contemporaneidade.The purpose of this paper is to provide insights into the history of the micareta in Brazil, from its origin as a mi-carême (mid-lent celebration) to its current expression. Although this research is in part a synthesis of the rare publications on the subject, most of the data comes from extensive historical archive research, carried out mainly in the Brazilian national and local press. The micareta is an old festival (started in 1908) and its history is closely linked to the carnival in Salvador. It resulted from an evolution of the trio elétrico and from the Bahian trio bands. Tied in with the successive waves of expansion of the micareta throughout Brazil, five distinct developmental stages are discussed. Their salient features reflect the gradual commercialization of the micareta

An Efficient Modular Method for the Control of Concurrent Discrete Event Systems: A Language-Based Approach

International audienceIn this paper, we are interested in the control of a particular class of Concurrent Discrete Event Systems defined by a collection of components that interact with each other. We investigate the computation of the supremal controllable language contained in the language of the specification. We do not adopt the decentralized approach. Instead, we have chosen to use a modular centralized approach and to perform the control on some approximations of the plant derived from the behavior of each component. The behavior of these approximations is restricted so that they respect a new language property for discrete event systems called partial controllability condition that depends on the specification. It is shown that, under some assumptions, the intersection of these ``controlled approximations'' corresponds to the supremal controllable language contained in the specification with respect to the plant. This computation is performed without having to build the whole plant, hence avoiding the state space explosion induced by the concurrent nature of the plant. It is finally shown that the class of specifications on which our method can be applied strictly subsumes the class of separable specifications

Safety Control of Hierarchical Synchronous Discrete Event Systems: A State-Based Approach

International audienceIn this paper, we discuss the control of a particular class of Hierarchical Discrete Event Systems and the state avoidance control problem is considered. A methodology is provided that locally computes on each component of the system the set of bad states (these are the states that may lead to the forbidden states via an uncontrollable trajectory). This is performed without computing the whole system. At this point, the supervisor is evaluated on the fly w.r.t. the bad states and thus requires an on-line evaluation in order to determine the set of events that has to be disabled by control. It is performed in such a way that the global partial transition function does not need to be built

Supervisory Control Problems of Hierarchical Finite State Machines

International audienceThe situation under consideration is that of a given Discrete Event System (DES), whose behavior has to be modified by means of a feedback control (named Supervisor) in order to achieve a given set of requirements that the initial DES did not satisfy. To do so, the DES is modeled as a Hierarchical Finite State Machine (HFSM). Further, instead of translating the HFSM to ordinary state machines and using classical synthesis tools on the resulting FSM, we here present algorithms that solve the Supervisory Control Problem (for a particular case of forbidden state avoidance problem) as well as the Optimal Control Problem without expanding the HFS

Supervisory Control of Product and Hierarchical Discrete Event Systems

International audienceIn this paper, the supervisory control of a class of Discrete Event Systems is investigated. Discrete event systems are modeled either by a collection of Finite State Machines that behave asynchronously or by a Hierarchical Finite State Machine. The basic problem of interest is to ensure the invariance of a set of particular configurations in the system. When the system is modeled as asynchronous FSMs, we provide algorithms that, based on a particular decomposition of the set of forbidden configurations, solve the control problem locally (i.e. on each component without computing the whole system) and produce a global supervisor ensuring the desired property. We then provide sufficient conditions under which the obtained controlled system is non-blocking. This kind of objectives may be useful to perform dynamic interactions between different parts of a system. Finally, we apply these results to the case of Hierarchical Finite State Machine

Supervisory Control and Deadlock Avoidance Control Problem for Concurrent Discrete Event Systems

International audienceIn this paper, we tackle the Supervisory Control Problem control for Concurrent Discrete Event Systems. These are systems that are defined by a collection of components that interact with each other. In this study, we first outline the method allowing to solve the state avoidance control problem on concurrent system, without having to compute the whole system. We then present results offering an efficient method to detect deadlock states in the controlled system due either to the composition or to the control that is performed on the syste

Supervisory Control of Asynchronous and Hierarchical Finite State Machines

International audienceIn this paper, modular supervisory control of a class of Discrete Event Systems is investigated. Discrete event systems are modeled by a Hierarchical Finite State Machine. The basic problem of interest is to solve the State Avoidance Control Problem. We provide algorithms that, based on a particular decomposition of the set of forbidden configurations, locally solve the control problem (i.e. on each component without computing the whole system) and produce a global supervisor ensuring the desired property. This kind of objectives may be useful to perform dynamic interactions between different parts of a syste

Une approche modulaire pour le contrôle de systèmes à événements discrets concurrents

National audienceDans cet article, nous nous intéressons au contrôle de systèmes à événements discrets concurrents définis par une collection de sous-systèmes interagissant les uns avec les autres. Étant donné un objectif de contrôle, le but consiste à calculer un superviseur maximal assurant cet objectif, sans construire explicitement le système à contrôler. Des approximations du système G sont dérivés à partir des sous-systèmes qui le composent, et une propriété appelée contrôlabilité partielle, devant être vérifiée par l'objectif sur ces approximations, est introduite. Assurer la contrôlabilité partielle de l'objectif sur chacune des approximations permet, sous certaines hypothèses, d'en déduire un superviseur maximal assurant l'objectif de contrôle sur G. Les calculs effectués ont une faible complexité et ne nécessitent pas de construire explicitement le système G, évitant ainsi l'explosion combinatoire inhérente aux systèmes concurrent

Contrôle de systèmes à événements discrets hiérarchiques

National audienceDans ce papier, nous nous intéressons au contrôle de systèmes à événements discrets modélisés par des machines à états finis hiérarchiques. Le problème du contrôle que nous nous posons est d'assurer l'interdiction d'un ensemble particulier de configurations dans le système. Nous présentons des algorithmes qui, basés sur une décomposition particulière de cet ensemble, résolvent localement les problèmes de contrôle (i.e. sur chaque composant du système sans avoir à calculer explicitement le système) et produisent un contrôleur global assurant la propriété attendue. Ce type d'objectifs peut être utilisé pour décrire/assurer des interactions entre différents sous-systèmes