Jugando con el tiempo : semántica de pruebas para algebras de procesos temporizadas

en el presente trabajo hemos estudiado la semántica de pruebas para alebras de procesos temporizadas. En primer lugar hemos estudiado un álgebra de procesos temporizada básica, se trata de un lenguaje recursivo, secuencial no determinista. Puesto que las semánticas de pruebas son poco manejables, se hace necesario dar una caracterización alternativa de la misma; nosotros hemos dado una caracterizacion que depende unicamente de la semántica operacional de álgebra. A continuación hemos dotado al álgebra de una semántica denotacional, que ha resultado ser completamente abstracta con respecto a la semántica de pruebas. Seguidamente hemos estudiado una semántica axiomática, puesto que conseguimos probar que esta ultima es correcta y completa con respecto a la semántica detonaciones tenemos inmediatamente que tambien será correcta y completa con respecto a la semántica de pruebas. Puesto que todo lo anterior lo habíamos hecho con un álgebra bastante simple, es necesario introducir operadores mas complejos. En concreto hemos estudiado una serie de operadores que aparecen en la mayoria de las alebras de procesos temporizadas: . El operador de paralelo. El operador de ocultamiento, y. El operador de prefijo mediante acción visible con intervalo de tiempo. Por ultimo hemos estudiado un operador de elección tipo ccs, que tiene los problemas típicos con respecto a la congruenci

Denotational semantics for timed testing

In this paper we present a denotational semantics for a timed process algebra, which is fully abstract with respect to the must testing semantics previously developed [Lla96,LdFN96]. The domain of semantic processes is made up of consistent sets of barbs, which generalize the notion of acceptance sets, in such a way that the actions that are offered but not taken in each state are also recorded. the main difficulty when defining this denotational semantics has been that the natural ordering between semantic processes cannot be proved to be complete. So an alternative stronger complete ordering has to be considered, which is proved to be consistent with the original one, in the sense that lubs of chains with respect to the new ordering are also lubs with respect to the original one

A Semantic Framework to Debug Parallel Lazy Functional Languages

It is not easy to debug lazy functional programs. The reason is that laziness and higherorder complicates basic debugging strategies. Although there exist several debuggers for sequential lazy languages, dealing with parallel languages is much harder. In this case, it is important to implement debugging platforms for parallel extensions, but it is also important to provide theoretical foundations to simplify the task of understanding the debugging process. In this work, we deal with the debugging process in two parallel languages that extend the lazy language Haskell. In particular, we provide an operational semantics that allows us to reason about our parallel extension of the sequential debugger Hood. In addition, we show how we can use it to analyze the amount of speculative work done by the processes, so that it can be used to optimize their use of resources

MT-EA4Cloud: A Methodology For testing and optimising energy-aware cloud systems

Currently, using conventional techniques for checking and optimising the energy consumption in cloud systems is unpractical, due to the massive computational resources required. An appropriate test suite focusing on the parts of the cloud to be tested must be efficiently synthesised and executed, while the correctness of the test results must be checked. Additionally, alternative cloud configurations that optimise the energetic consumption of the cloud must be generated and analysed accordingly, which is challenging. To solve these issues we present MT-EA4Cloud, a formal approach to check the correctness – from an energy-aware point of view – of cloud systems and optimise their energy consumption. To make the checking of energy consumption practical, MT-EA4Cloud combines metamorphic testing, evolutionary algorithms and simulation. Metamorphic testing allows to formally model the underlying cloud infrastructure in the form of metamorphic relations. We use metamorphic testing to alleviate both the reliable test set problem, generating appropriate test suites focused on the features reflected in the metamorphic relations, and the oracle problem, using the metamorphic relations to check the generated results automatically. MT-EA4Cloud uses evolutionary algorithms to efficiently guide the search for optimising the energetic consumption of cloud systems, which can be calculated using different cloud simulators

Quantum invariants for the graph isomorphism problem

Graph Isomorphism is such an important problem in computer science, that it has been widely studied over the last decades. It is well known that it belongs to NP class, but is not NP-complete. It is thought to be of comparable difficulty to integer factorisation. The best known proved algorithm to solve this problem in general, was proposed by László Babai and Eugene Luks in 1983. Recently, there has been some research in the topic by using quantum computing, that also leads the present piece of research. In fact, we present a quantum computing algorithm that defines an invariant over Graph Isomorphism characterisation. This quantum algorithm is able to distinguish more non-isomorphic graphs than most of the known invariants so far. The proof of correctness and some hints illustrating the extent and reason of the improvement are also included in this paper

Empleo de herramientas de simulación con fines docentes para desarrollar prácticas de sistemas altamente distribuidos

El objetivo de este proyecto consiste en mitigar los problemas existentes para ejecutar aplicaciones distribuidas en las prácticas de la asignatura Programación de Sistemas Distribuidos. Para ello proponemos el uso del simulador SIMCAN, el cual ha sido validado contra arquitecturas reales. Concretamente, se propone adaptar este simulador, desarrollado en el contexto de la investigación, para fines docentes. Seguidamente, se utilizará la versión adaptada de SIMCAN en las prácticas de la asignatura Programación de Sistemas Distribuidos, del grado de Ingeniería de Computadores de la FDI/UCM

EXERCITA: una base de datos de material para prácticas de programación

Presentamos en este artículo el diseño y realización de una base de datos de materiales y herramientas para la práctica de la programación. El núcleo de dicha base de datos es el lenguaje eXercita, cuya descripción, implementación y uso se explican en estas páginas. Se expone igualmente la organización del contenido de la base de datos (principalmente ejercicios y prácticas), que da cuenta de sus posibilidades, flexibilidad y amplitud. Estas herramientas permiten distribuir el material en papel o en formato electrónico, ya sea mediante CD-ROM o a través de Internet

Análisis de rendimiento de aplicaciones MPI en clusters de Raspberries Pi3

La asignatura Programación de Sistemas Distribuidos (PSD) dedica una parte del temario a las aplicaciones de alto rendimiento y, en particular, a las aplicaciones desarrolladas con MPI. En resumen, estas aplicaciones despliegan en las máquinas físicas del sistema distribuido una serie de procesos, los cuales deben explotar -de la forma más eficiente posible- los recursos compartidos del sistema para incrementar su rendimiento. El objetivo principal de este proyecto consiste en analizar el rendimiento de clusters de bajo presupuesto, concretamente, de sistemas formados por placas Raspberry Pi3

Introducing friendly testing

We present a new testing semantics, called friendly testing, whose main property is that the induced preorder between processes v fr is consistent with the conformance relation, and so we have, for instance, a \Phi b v fr a v fr a + b. The new theory is strongly based on De Nicola & Hennessy's work on testing, and the structure of the paper closely follows that of Hennessy's book on the subject. Friendly tests are defined exactly as in his famous book, except that internal actions are not owed. However, this restriction is not enough and we also have to relax the conditions to pass a test in order to obtain the desired notion of friendly testing. Thus we obtain a new testing semantics and a new preorder between processes which is strictly weaker than the relation vmust . As a consequence, a fully abstract denotational semantics can be obtained as a quotient algebra of the corresponding construction for the must semantics, and the addition to the complete axiomatization of the latter of a single conformance axiom, gives us a complete axiomatization of our friendly testing semantics