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A communicating system is k -synchronizable if all of the message sequence charts representing the executions can be divided into slices of k sends followed by k receptions. It was previously shown that, for a fixed given k , one could decide whether a communicating system is k -synchronizable. This result is interesting because the reachability problem can be solved for k -synchronizable systems. However, the decision procedure assumes that the bound k is fixed. In this paper we improve this result and show, for mailbox communication, that it is possible to decide if such a bound k exists. [ABSTRACT FROM AUTHOR]

In this paper we address the issue of automatically learning parameters of spiking neural networks. Biological neurons are formalized as timed automata and synaptical connections are represented as shared channels among these automata. Such a formalism allows us to take into account several time-related aspects, such as the influence of past inputs in the computation of the potential value of each neuron, or the presence of the refractory period, a lapse of time immediately following the spike emission in which the neuron cannot emit. The proposed model is then formally validated: more precisely, we ensure that some relevant properties expressed as temporal logical formulae hold in the model. Once the validation step is accomplished, we take advantage of the proposed model to write an algorithm for learning synaptical weight values such that an expected behavior can be displayed. The technique we present takes inspiration from supervised learning ones: we compare the effective output of the network to the expected one and backpropagate proper corrective actions in the network. We develop several case studies including a mutual inhibition network. [ABSTRACT FROM AUTHOR]

ANDy, Activity Networks with Delays, is a discrete framework aiming at the qualitative modeling of time-dependent activities. The modular and expressive syntax makes ANDy suitable for a concise and natural modeling of time-dependent biological systems (i.e., regulatory pathways). Activities involve entities playing the role of activators, inhibitors or products of biochemical network operation. Activities may have a given duration, i.e., the time required to obtain results. An entity may represent an object (e.g., an agent, a biochemical species or a family of thereof) with a local attribute, a state denoting its level (e.g., concentration, strength). Entity levels may change as a result of an activity or may decay gradually as time passes by. The semantics of ANDy is formally given via high-level Petri nets ensuring this way some modularity. As main results we show that ANDy systems have finite state representations even for potentially infinite processes and it well adapts to the modeling of toxic behaviors. As an illustration, we present a classification of toxicity properties and give some hints on how they can be verified on ANDy systems with existing tools. A case study on blood glucose regulation is provided to exemplify the ANDy framework and the toxicity properties. [ABSTRACT FROM AUTHOR]

Communication-centric systems are software systems built as assemblies of distributed artifacts that interact following predefined communication protocols. Session-based concurrency is a type-based approach to ensure the conformance of communication-centric systems to such protocols. This paper presents a model of session-based concurrency with mechanisms for run-time adaptation. Our model allows us to specify communication-centric systems whose session behavior can be dynamically updated at run-time. We improve on previous work by proposing an event-based approach: adaptation requests, issued by the system itself or by its context, are assimilated to events which may trigger adaptation routines. These routines exploit type-directed checks to enable the reconfiguration of processes with active protocols. We equip our model with a type system that ensures communication safety and consistency properties: while safety guarantees absence of run-time communication errors, consistency ensures that update actions do not disrupt already established session protocols. We provide soundness results for binary and multiparty protocols. [ABSTRACT FROM AUTHOR]

Session types offer a powerful type-theoretic foundation for the analysis of structured communications, as commonly found in service-oriented systems. They are defined upon core programming calculi which offer only limited support for expressing requirements related to runtime adaptation . This is unfortunate, as service-oriented systems are increasingly being deployed upon highly dynamic infrastructures in which such requirements are central concerns. In previous work, we developed a process calculi framework of adaptable processes , in which concurrent processes can be replaced, suspended, or discarded at runtime. In this paper, we propose a session type discipline for a calculus with adaptable processes. Our typed framework offers a simple alternative for integrating runtime adaptation mechanisms in the modeling and analysis of structured communications. We show that well-typed processes enjoy safety and consistency properties: while the former property ensures the absence of communication errors at runtime, the latter guarantees that active session behavior is never disrupted by adaptation actions. [ABSTRACT FROM AUTHOR]