4,027 research outputs found
An Introduction to Pervasive Interface Automata
Pervasive systems are often context-dependent, component based systems in which components expose interfaces and offer one or more services. These systems may evolve in unpredictable ways, often through component replacement. We present pervasive interface automata as a formalism for modelling components and their composition. Pervasive interface automata are based on the interface automata of Henzinger et al, with several significant differences. We expand their notion of input and output actions to combinations of input, output actions, and callable methods and method calls. Whereas interfaces automata have a refinement relation, we argue the crucial relation in pervasive systems is component replacement, which must include consideration of the services offered by a component and assumptions about the environment. We illustrate pervasive interface autmotata and component replacement with a small case study of a pervasive application for sports predictions
An Algorithm for Probabilistic Alternating Simulation
In probabilistic game structures, probabilistic alternating simulation
(PA-simulation) relations preserve formulas defined in probabilistic
alternating-time temporal logic with respect to the behaviour of a subset of
players. We propose a partition based algorithm for computing the largest
PA-simulation, which is to our knowledge the first such algorithm that works in
polynomial time, by extending the generalised coarsest partition problem (GCPP)
in a game-based setting with mixed strategies. The algorithm has higher
complexities than those in the literature for non-probabilistic simulation and
probabilistic simulation without mixed actions, but slightly improves the
existing result for computing probabilistic simulation with respect to mixed
actions.Comment: We've fixed a problem in the SOFSEM'12 conference versio
La televisión como generadora de pautas de conducta en jóvenes salvadoreños
Este informe es producto de una investigación correlacional descriptiva realizada entre 1.207 jóvenes salvadoreños, con el objetivo de determinar si existe relación entre sus hábitos de consumo televisivo y sus pautas de conducta. Los resultados apuntan a la televisión como medio dominante —en la que se busca sobre todo entretenimiento—, con la Internet afianzándose en un sólido segundo lugar. Sin embargo, esa preferencia por el medio, aun y cuando los datos obtenidos permiten percibir una asociación entre su consumo y la manera en la que los jóvenes hablan, se comportan, lucen o piensan, no llegan a establecerse correlaciones estadísticas, con lo que habría que virar la vista hacia los hechos de que los receptores tienen un papel activo; que la influencia de la televisión no es una variable unidimensional, y que las interacciones sociales y el contexto deben ser considerados con profundidad. Para ello, es necesario recurrir a otros enfoques en la investigación, al estudio cualitativo. No obstante, la adopción de estrategias de educación para los medios, y especialmente para el consumo de la televisión, es una necesidad que se impone.La presente investigación fue subvencionada por la Universidad Tecnológica de El Salvador. Las solicitudes de información, separatas y otros documentos relativos al presente estudio pueden hacerse a la dirección postal: calle Arce, 1020, Universidad Tecnológica de El Salvador, Vicerrectoría de Investigación, Dirección de Investigaciones, calle Arce y 17ª. Avenida Norte, edificio José Martí, 2ª. Planta, o al correo electrónico [email protected] Tecnológica de El Salvado
Algorithms for Game Metrics
Simulation and bisimulation metrics for stochastic systems provide a
quantitative generalization of the classical simulation and bisimulation
relations. These metrics capture the similarity of states with respect to
quantitative specifications written in the quantitative {\mu}-calculus and
related probabilistic logics. We first show that the metrics provide a bound
for the difference in long-run average and discounted average behavior across
states, indicating that the metrics can be used both in system verification,
and in performance evaluation. For turn-based games and MDPs, we provide a
polynomial-time algorithm for the computation of the one-step metric distance
between states. The algorithm is based on linear programming; it improves on
the previous known exponential-time algorithm based on a reduction to the
theory of reals. We then present PSPACE algorithms for both the decision
problem and the problem of approximating the metric distance between two
states, matching the best known algorithms for Markov chains. For the
bisimulation kernel of the metric our algorithm works in time O(n^4) for both
turn-based games and MDPs; improving the previously best known O(n^9\cdot
log(n)) time algorithm for MDPs. For a concurrent game G, we show that
computing the exact distance between states is at least as hard as computing
the value of concurrent reachability games and the square-root-sum problem in
computational geometry. We show that checking whether the metric distance is
bounded by a rational r, can be done via a reduction to the theory of real
closed fields, involving a formula with three quantifier alternations, yielding
O(|G|^O(|G|^5)) time complexity, improving the previously known reduction,
which yielded O(|G|^O(|G|^7)) time complexity. These algorithms can be iterated
to approximate the metrics using binary search.Comment: 27 pages. Full version of the paper accepted at FSTTCS 200
Three Body Interactions, Angular Momentum and Black Hole Moduli Spaces
We investigate the dynamics of a pair of (4+1)-dimensional black holes in the
moduli approximation and with fixed angular momentum. We find that spinning
black holes at small separations are described by the de Alfaro, Fubini and
Furlan model. For more than two black holes, we find an explicit expression for
the three-body interactions in the moduli metric by associating them with the
one-loop three-point amplitude of a four-dimensional theory. We also
investigate the dynamics of a three black hole system in various
approximations.Comment: 20 pages, phyzz
New insight into WDVV equation
We show that Witten-Dijkgraaf-Verlinde-Verlinde equation underlies the
construction of N=4 superconformal multi--particle mechanics in one dimension,
including a N=4 superconformal Calogero model.Comment: 16 pages, no figures, LaTeX file, PACS: 04.60.Ds; 11.30.P
Adaptable transition systems
We present an essential model of adaptable transition systems inspired by white-box approaches to adaptation and based on foundational models of component based systems. The key feature of adaptable transition systems are control propositions, imposing a clear separation between ordinary, functional behaviours and adaptive ones. We instantiate our approach on interface automata yielding adaptable interface automata, but it may be instantiated on other foundational models of component-based systems as well. We discuss how control propositions can be exploited in the specification and analysis of adaptive systems, focusing on various notions proposed in the literature, like adaptability, control loops, and control synthesis
Average Effective Potential for the Conformal Factor
In a four dimensional theory of gravity with lagrangian quadratic in
curvature and torsion, we compute the effective action for metrics of the form
, with constant. Using standard
field-theoretic methods we find that one loop quantum effects produce a
nontrivial effective potential for . We explain this unexpected result by
showing how our regularization procedure differs from the one that is usually
adopted in Quantum Gravity. Using the method of the average effective
potential, we compute the scale dependence of the v.e.v. of the conformal
factor.Comment: 8 pages, plain TEX, SISSA 71/93-E
Mean-payoff Automaton Expressions
Quantitative languages are an extension of boolean languages that assign to
each word a real number. Mean-payoff automata are finite automata with
numerical weights on transitions that assign to each infinite path the long-run
average of the transition weights. When the mode of branching of the automaton
is deterministic, nondeterministic, or alternating, the corresponding class of
quantitative languages is not robust as it is not closed under the pointwise
operations of max, min, sum, and numerical complement. Nondeterministic and
alternating mean-payoff automata are not decidable either, as the quantitative
generalization of the problems of universality and language inclusion is
undecidable.
We introduce a new class of quantitative languages, defined by mean-payoff
automaton expressions, which is robust and decidable: it is closed under the
four pointwise operations, and we show that all decision problems are decidable
for this class. Mean-payoff automaton expressions subsume deterministic
mean-payoff automata, and we show that they have expressive power incomparable
to nondeterministic and alternating mean-payoff automata. We also present for
the first time an algorithm to compute distance between two quantitative
languages, and in our case the quantitative languages are given as mean-payoff
automaton expressions
- …