Talking quiescence: a rigorous theory that supports parallel composition, action hiding and determinisation

The notion of quiescence - the absence of outputs - is vital in both behavioural modelling and testing theory. Although the need for quiescence was already recognised in the 90s, it has only been treated as a second-class citizen thus far. This paper moves quiescence into the foreground and introduces the notion of quiescent transition systems (QTSs): an extension of regular input-output transition systems (IOTSs) in which quiescence is represented explicitly, via quiescent transitions. Four carefully crafted rules on the use of quiescent transitions ensure that our QTSs naturally capture quiescent behaviour. We present the building blocks for a comprehensive theory on QTSs supporting parallel composition, action hiding and determinisation. In particular, we prove that these operations preserve all the aforementioned rules. Additionally, we provide a way to transform existing IOTSs into QTSs, allowing even IOTSs as input that already contain some quiescent transitions. As an important application, we show how our QTS framework simplifies the fundamental model-based testing theory formalised around ioco.Comment: In Proceedings MBT 2012, arXiv:1202.582

Protocol-Inspired Hardware Testing

The relevance of protocol conformance testing techniques to hardware testing is discussed. It is shown that the ioconf (input-output conformance) approach used in protocol testing can be applied to generate tests for a synchronous hardware design using its formal specification. The generated tests are automatically applied to a circuit by a VHDL testbench, thus giving confidence that the hardware design meets its high-level formal specification. Case studies illustrate how the ideas can be applied to standard hardware verification benchmarks such as the Single Pulser and Black-Jack Dealer

Vivienda contemporánea: apuntes para una teoría

Desde hace más de cien años, las reflexiones sobre la vivienda y sobre la arquitectura institucional y pública vienen desarrollándose de forma independiente en lo que respecta a métodos indagatorios, planteamientos teóricos, análisis críticos o sistemas clasificatorios. Hablar hoy de vivienda requiere términos específicos de carácter racional, objetivo, funcional o económico en respuesta a los que hasta hace poco avalaron los recientes dispendios formales y estructurales. El objetivo de la presente propuesta es localizar y analizar algunas de las palabras que empiezan a describir los actuales problemas de vivienda para construir con ellas los fundamentos teóricos que cabe deducir de los propios proyectos y de las ideas que sus arquitectos explicitan y sus críticos aportan, tratando de reconocer procedimientos de renovación proyectual, iniciativas experimentales y recientes concepciones residenciales. Términos como vivienda base, dispersión doméstica, atomización, flexibilidad, neutralidad, post-espacio público, reversibilidad, vivienda-ciudad o hibridación están consolidando nociones asociadas a nuevas formas de habitar que hacen inservibles muchas fórmulas convencionales. Extraer algunas de estas ideas estudiando ciertos conjuntos residenciales puede contribuir a hacer comprensible el panorama de la arquitectura doméstica actual, aportando una teoría propia, distinta a las tan consistentes de la primera mitad del siglo XX, pero reveladora tanto de continuidades con ellas como de novedades o cambios sustanciales de sus significados originales (este es el caso de la flexibilidad) o de completas desapariciones, como la otrora esencial búsqueda del Existenzminimum, hoy sustituida por las esperanzadoras nociones de espacio-extra o más por menos. Nuestro esfuerzo como equipo de investigación está orientado a contribuir con un glosario y, por tanto, un ideario, que ayude a construir la necesaria teoría de la vivienda del nuevo siglo

Compositional schedulability analysis of real-time actor-based systems

We present an extension of the actor model with real-time, including deadlines associated with messages, and explicit application-level scheduling policies, e.g.,"earliest deadline first" which can be associated with individual actors. Schedulability analysis in this setting amounts to checking whether, given a scheduling policy for each actor, every task is processed within its designated deadline. To check schedulability, we introduce a compositional automata-theoretic approach, based on maximal use of model checking combined with testing. Behavioral interfaces define what an actor expects from the environment, and the deadlines for messages given these assumptions. We use model checking to verify that actors match their behavioral interfaces. We extend timed automata refinement with the notion of deadlines and use it to define compatibility of actor environments with the behavioral interfaces. Model checking of compatibility is computationally hard, so we propose a special testing process. We show that the analyses are decidable and automate the process using the Uppaal model checke

Conformance-based doping detection for cyber-physical systems

We present a novel and generalised notion of doping cleanness for cyber-physical systems that allows for perturbing the inputs and observing the perturbed outputs both in the time– and value–domains. We instantiate our definition using existing notions of conformance for cyber-physical systems. We show that our generalised definitions are essential in a data-driven method for doping detection and apply our definitions to a case study concerning diesel emission tests