Graphical representation of covariant-contravariant modal formulae

Covariant-contravariant simulation is a combination of standard (covariant) simulation, its contravariant counterpart and bisimulation. We have previously studied its logical characterization by means of the covariant-contravariant modal logic. Moreover, we have investigated the relationships between this model and that of modal transition systems, where two kinds of transitions (the so-called may and must transitions) were combined in order to obtain a simple framework to express a notion of refinement over state-transition models. In a classic paper, Boudol and Larsen established a precise connection between the graphical approach, by means of modal transition systems, and the logical approach, based on Hennessy-Milner logic without negation, to system specification. They obtained a (graphical) representation theorem proving that a formula can be represented by a term if, and only if, it is consistent and prime. We show in this paper that the formulae from the covariant-contravariant modal logic that admit a "graphical" representation by means of processes, modulo the covariant-contravariant simulation preorder, are also the consistent and prime ones. In order to obtain the desired graphical representation result, we first restrict ourselves to the case of covariant-contravariant systems without bivariant actions. Bivariant actions can be incorporated later by means of an encoding that splits each bivariant action into its covariant and its contravariant parts.Comment: In Proceedings EXPRESS 2011, arXiv:1108.407

Equational Characterization of Covariant-Contravariant Simulation and Conformance Simulation Semantics

Covariant-contravariant simulation and conformance simulation generalize plain simulation and try to capture the fact that it is not always the case that "the larger the number of behaviors, the better". We have previously studied their logical characterizations and in this paper we present the axiomatizations of the preorders defined by the new simulation relations and their induced equivalences. The interest of our results lies in the fact that the axiomatizations help us to know the new simulations better, understanding in particular the role of the contravariant characteristics and their interplay with the covariant ones; moreover, the axiomatizations provide us with a powerful tool to (algebraically) prove results of the corresponding semantics. But we also consider our results interesting from a metatheoretical point of view: the fact that the covariant-contravariant simulation equivalence is indeed ground axiomatizable when there is no action that exhibits both a covariant and a contravariant behaviour, but becomes non-axiomatizable whenever we have together actions of that kind and either covariant or contravariant actions, offers us a new subtle example of the narrow border separating axiomatizable and non-axiomatizable semantics. We expect that by studying these examples we will be able to develop a general theory separating axiomatizable and non-axiomatizable semantics.Comment: In Proceedings SOS 2010, arXiv:1008.190

FVE project manager: gestión de procesos software y control de versiones sobre dotproject

Nuestro proyecto tiene como finalidad aportar una aplicación libre y de código abierto que permita asistir en el desarrollo de un proyecto software facilitando la elección de un proceso de desarrollo; su ejecución entendida como la obtención de los resultados esperables de un proceso de desarrollo; y el acceso al mismo por parte de los participantes elegidos. Esta aplicación se llama FVE Project Manager. Existen algunas soluciones libres, pero distan mucho de ser completas, sobre todo por no estar integradas con sistemas de control de versiones. Así, en lugar de iniciar un proyecto desde cero, decidimos modificar un gestor de proyectos existente, dotProject, ampliando sus características. Con nuestra herramienta se pueden crear nuevas definiciones de procesos o importarlas en formato XML desde EPFComposer. Se permite la creación de productos de trabajo, gestión de los roles del proceso y personalización de las tareas. Una vez instanciado el proceso, los participantes pueden empezar a trabajar en el proyecto con todos los elementos definidos en el mismo mediante una intuitiva interfaz gráfica que brinda la aplicación. Otro logro notable es el de integrar un sistema de control de cambios (SVN). Ahora mismo, no existe ninguna extensión de dotproject para soportar SVN. Este servicio se integra de tal forma que no hay necesidad de que el cliente instale ningún tipo de programa adicional en su ordenador, pudiendo además acceder a este repositorio de forma independiente a dotProject. El sistema ha sido desarrollado en los lenguajes PHP, JSP, Java y Javascript y requiere para su despliegue de un servidor con servicios web compatibles con PHP, un servidor de base de datos MySQL, un servidor de aplicaciones para J2EE y la instalación de los servicios de Subversion en el servidor. Todas las herramientas utilizadas para el desarrollo son Open Source, por lo que podemos devolver a la comunidad de desarrolladores el beneficio de poder usar estas herramientas con una aplicación libre que ofrece servicios disponibles generalmente bajo pago. La agrupación de todas estas características sobre un gestor de proyectos libre como dotProject supone la creación de una funcionalidad no existente en aplicaciones libres y da respuesta a un gran número de solicitudes por parte de la comunidad de usuarios. [ABSTRACT] The purpose of our project is contributing a free and Open Source application that allows the administration of a project management entire cycle by the supplying of new functionalities that provide more power and flexibility to the execution of these projects. The name of this application is FVE Project Manager. There are several free solutions, but they are far from being complete, especially for not being integrated with version control systems. So, instead of starting a project from scratch, we decided to modify an existing project manager, dotproject, expanding its features. With our tool it is possible to create new process definitions or import them in XML format from EPFComposer. It allows the creation of workproducts, process roles management and personalization of the process of tasks. Once the process is instantiated, the participants may start working on it with all the defined elements in it through an intuitive graphical interface that the application provides. Another remarkable achievement is integrating a version control system (SVN). Right now, there is no extension of dotproject that works with SVN. This service is integrated so that there is no need for the customer to install any additional software on his computer. He can also access this repository independently from dotproject. The system has been developed in PHP, JSP, Java and Javascript languages. It requires for its deployment a PHP compatible web services server, a MySQL database server, a J2EE application server and the installation of the Subversion services in the server. All the tools that we used in the development are Open Source, so we can return to the developer community the benefit of being able to use these tools with a free application that provides non-free services. The grouping of all these features on a free project manager as dotproject involves creating a non-existent feature in free applications and responded to numerous requests by the user community

Rule Formats for Nominal Process Calculi

The nominal transition systems (NTSs) of Parrow et al. describe the operational semantics of nominal process calculi. We study NTSs in terms of the nominal residual transition systems (NRTSs) that we introduce. We provide rule formats for the specifications of NRTSs that ensure that the associated NRTS is an NTS and apply them to the operational specifications of the early and late pi-calculus. We also explore alternative specifications of the NTSs in which we allow residuals of abstraction sort, and introduce translations between the systems with and without residuals of abstraction sort. Our study stems from the Nominal SOS of Cimini et al. and from earlier works in nominal sets and nominal logic by Gabbay, Pitts and their collaborators

Reflection and Preservation of Properties in Coalgebraic (bi)Simulations

Our objective is to extend the standard results of preservation and reflection of properties by bisimulations to the coalgebraic setting, as well as to study under what conditions these results hold for simulations. The notion of bisimulation is the classical one, while for simulations we use that proposed by Hughes and Jacobs. As for properties, we start by using a generalization of linear temporal logic to arbitrary coalgebras suggested by Jacobs, and then an extension by Kurtz which includes atomic propositions too

Non-strongly stable orders also define interesting simulation relations

We present a study of the notion of coalgebraic simulation introduced by Hughes and Jacobs. Although in their original paper they allow any functorial order in their definition of coalgebraic simulation, for the simulation relations to have good properties they focus their attention on functors with orders which are strongly stable. This guarantees a so-called “composition-preserving” property from which all the desired good properties follow. We have noticed that the notion of strong stability not only ensures such good properties but also “distinguishes the direction” of the simulation. For example, the classic notion of simulation for labeled transition systems, the relation “p is simulated by q”, can be defined as a coalgebraic simulation relation by means of a strongly stable order, whereas the opposite relation, “p simulates q”, cannot. Our study was motivated by some interesting classes of simulations that illustrate the application of these results: covariant-contravariant simulations and conformance simulations

Rule Formats for Nominal Process Calculi

The nominal transition systems (NTSs) of Parrow et al. describe the operational semantics of nominal process calculi. We study NTSs in terms of the nominal residual transition systems (NRTSs) that we introduce. We provide rule formats for the specifications of NRTSs that ensure that the associated NRTS is an NTS and apply them to the operational specifications of the early and late pi-calculus. We also explore alternative specifications of the NTSs in which we allow residuals of abstraction sort, and introduce translations between the systems with and without residuals of abstraction sort. Our study stems from the Nominal SOS of Cimini et al. and from earlier works in nominal sets and nominal logic by Gabbay, Pitts and their collaborators

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