Investigating Strategies for Cooperative Planning of Independent Agents through Prototype Evaluation

This paper discusses the application of the prototyping approach to investigating the requirements on strategies for cooperative planning and conflict resolution of independent agents by means of an example application: the strategic game "Scotland Yard". The strategies for coordinating the agents, which are parallel algorithms, are developed with a prototyping approach using ProSet-Linda. ProSet-Linda designed for prototyping parallel algorithms. We concentrate o

Strong Completeness for Markovian Logics

In this paper we present Hilbert-style axiomatizations for three logics for reasoning about continuous-space Markov processes (MPs): (i) a logic for MPs defined for probability distributions on measurable state spaces, (ii) a logic for MPs defined for sub-probability distributions and (iii) a logic defined for arbitrary distributions.These logics are not compact so one needs infinitary rules in order to obtain strong completeness results. We propose a new infinitary rule that replaces the so-called Countable Additivity Rule (CAR) currently used in the literature to address the problem of proving strong completeness for these and similar logics. Unlike the CAR, our rule has a countable set of instances; consequently it allows us to apply the Rasiowa-Sikorski lemma for establishing strong completeness. Our proof method is novel and it can be used for other logics as well

Probabilistic Bisimulation: Naturally on Distributions

In contrast to the usual understanding of probabilistic systems as stochastic processes, recently these systems have also been regarded as transformers of probabilities. In this paper, we give a natural definition of strong bisimulation for probabilistic systems corresponding to this view that treats probability distributions as first-class citizens. Our definition applies in the same way to discrete systems as well as to systems with uncountable state and action spaces. Several examples demonstrate that our definition refines the understanding of behavioural equivalences of probabilistic systems. In particular, it solves a long-standing open problem concerning the representation of memoryless continuous time by memory-full continuous time. Finally, we give algorithms for computing this bisimulation not only for finite but also for classes of uncountably infinite systems

Semantics for probabilistic programming: higher-order functions, continuous distributions, and soft constraints

We study the semantic foundation of expressive probabilistic programming languages, that support higher-order functions, continuous distributions, and soft constraints (such as Anglican, Church, and Venture). We define a metalanguage (an idealised version of Anglican) for probabilistic computation with the above features, develop both operational and denotational semantics, and prove soundness, adequacy, and termination. They involve measure theory, stochastic labelled transition systems, and functor categories, but admit intuitive computational readings, one of which views sampled random variables as dynamically allocated read-only variables. We apply our semantics to validate nontrivial equations underlying the correctness of certain compiler optimisations and inference algorithms such as sequential Monte Carlo simulation. The language enables defining probability distributions on higher-order functions, and we study their properties

ER modelling from first relational principles

Entity-Relationship (ER) modelling is a popular technique for data modelling. Despite its popularity and widespread use, it lacks a firm semantic foundation. We propose a translation of an ER-model into relation algebra, suggesting that this kind of algebra does provide suitable mechanisms for establishing a formal semantics of ER modelling. The work reported on here deals first with the techniques necessary for the translation, thus constructing a static view of an ER-model in an abstract setting of what might be called logic without variables. We then undertake a detailed analysis of the insertion and deletion operations for an ER-model represented in terms of the relation calculus