Unwinding biological systems

Unwinding conditions have been fruitfully exploited in Information Flow Security to define persistent security properties. In this paper we investigate their meaning and possible uses in the analysis of biological systems. In particular, we elaborate on the notion of robustness and propose some instances of unwinding over the process algebra Bio-PEPA and over hybrid automata. We exploit such instances to analyse two case-studies: Neurospora crassa circadian system and Influenza kinetics models

Commande d'une classe de systèmes hybrides par automates hybrides rectangulaires

Notre travail de recherche concerne l étude de la commande à base de modèles pour une sous-classe de systèmes dynamiques hybrides (SDH). L outil de modélisation choisi est l automate hybride rectangulaire (AHR) pour sa puissance d analyse. Nous proposons ainsi une méthode pour la synthèse de la commande des SDH modélisés par des AHR. Cette méthode repose sur l application d une procédure amont/aval de commande hors-ligne qui détermine d une façon maximale permissive les nouvelles gardes de transition de l automate respectant des spécifications de commande imposées par l utilisateur. Tous les calculs réalisés reposent sur la détermination de la durée de séjour, valeur contrainte par l espace atteignable du sommet correspondant. La garde portant à la fois sur l état continu et sur l événement discret, la commande se fait par ce dernier car il s agit du seul élément contrôlable. Nous nous intéressons alors à la construction du contrôleur temporisé autorisant l occurrence des événements contrôlables du système dans un intervalle d horloge défini au sens de la maximale permissivité.In this thesis, we study the control of a class of hybrid dynamic systems (HDS). The chosen modeling tool is the rectangular hybrid automaton (RHA) for his analysis power. We propose a method for the control synthesis of HDS modeled with RHA. This method consists on the application of a downstream/upstream offline control procedure that determines in a maximal permissive way the new automaton transition guards respecting the desired control specifications. All computations are based on the determination of the duration of stay, a value constrained by the reachable space of the corresponding location. Since the guard refers to both continuous state and discrete event, the control is made by the latter because it is the controllable element. Then we are interested in the construction of the timed controller authorizing the system controllable event occurrence in a clock interval defined in a maximal permissive way.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

State Equivalences for Rectangular Hybrid Automata

. Three natural equivalence relations on the infinite state space of a hybrid automaton are language equivalence, simulation equivalence, and bisimulation equivalence. When one of these equivalence relations has a finite quotient, certain model checking and controller synthesis problems are decidable. When bounds on the number of equivalence classes are obtained, bounds on the running times of model checking and synthesis algorithms follow as corollaries. We characterize the time-abstract versions of these equivalence relations on the state spaces of rectangular hybrid automata (RHA), in which each continuous variable is a clock with bounded drift. These automata are useful for modeling communications protocols with drifting local clocks, and for the conservative approximation of more complex hybrid systems. Of our two main results, one has positive implications for automatic verification, and the other has negative implications. On the positive side, we find that the (finite) language..

State Equivalences for Rectangular Hybrid Automata

Three natural equivalence relations on the infinite state space of a hybrid automaton are language equivalence, simulation equivalence, and bisimulation equivalence. When one of these equivalence relations has a finite quotient, certain model checking and controller synthesis problems are decidable. When bounds on the number of equivalence classes are obtained, bounds on the running times of model checking and synthesis algorithms follow as corollaries. We characterize the time-abstract versions of these equivalence relations on the state spaces of rectangular hybrid automata (RHA), in which each continuous variable is a clock with bounded drift. These automata are useful for modeling communications protocols with drifting local clocks, and for the conservative approximation of more complex hybrid systems. Of our two main results, one has positive implications for automatic veri cation, and the other has negative implications. On the positive side, we find that the (finite) language equivalence quotient for RHA is coarser than was previously known by a multiplicative exponential factor. On the negative side, we show that simulation equivalence for RHA is equality (which obviously has an infinit