A semantics for behavior trees

In this paper we give a formal definition of the requirements translation language Behavior Trees. This language has been used with success in industry to systematically translate large, complex, and often erroneous requirements documents into a structured model of the system. It contains a mixture of state-based manipulations, synchronisation, message passing, and parallel, conditional, and iterative control structures. The formal semantics of a Behavior Tree is given via a structure-preserving translation to a version of Hoare’s process algebra CSP, extended with state-based constructs such as guards and updates, and a message passing facility similar to that used in publish/subscribe protocols. We first provide the extension of CSP and its operational semantics, which preserves the meaning of the original CSP operators, and then the Behavior Tree notation and its translation into the extended version of CSP

A semantics for Behavior Trees using CSP with specification commands

AbstractIn this paper we give a formal definition of the requirements translation language Behavior Trees. This language has been used with success in industry to systematically translate large, complex, and often erroneous requirements documents into a structured model of the system. It contains a mixture of state-based manipulations, synchronisation, message passing, and parallel, conditional, and iterative control structures. The formal semantics of a Behavior Tree is given via a translation to a version of Hoare’s process algebra CSP, extended with state-based constructs such as guards and updates, and a message passing facility similar to that used in publish/subscribe protocols. We first provide the extension of CSP and its operational semantics, which preserves the meaning of the original CSP operators, and then the Behavior Tree notation and its translation into the extended version of CSP

A type reduction theory for systems with replicated components

The Parameterised Model Checking Problem asks whether an implementation Impl(t) satisfies a specification Spec(t) for all instantiations of parameter t. In general, t can determine numerous entities: the number of processes used in a network, the type of data, the capacities of buffers, etc. The main theme of this paper is automation of uniform verification of a subclass of PMCP with the parameter of the first kind, i.e. the number of processes in the network. We use CSP as our formalism. We present a type reduction theory, which, for a given verification problem, establishes a function \phi that maps all (sufficiently large) instantiations T of the parameter to some fixed type T^ and allows us to deduce that if Spec(T^) is refined by \phi(Impl(T)), then (subject to certain assumptions) Spec(T) is refined by Impl(T). The theory can be used in practice by combining it with a suitable abstraction method that produces a t-independent process Abstr that is refined by {\phi}(Impl(T)) for all sufficiently large T. Then, by testing (with a model checker) if the abstract model Abstr refines Spec(T^), we can deduce a positive answer to the original uniform verification problem. The type reduction theory relies on symbolic representation of process behaviour. We develop a symbolic operational semantics for CSP processes that satisfy certain normality requirements, and we provide a set of translation rules that allow us to concretise symbolic transition graphs. Based on this, we prove results that allow us to infer behaviours of a process instantiated with uncollapsed types from known behaviours of the same process instantiated with a reduced type. One of the main advantages of our symbolic operational semantics and the type reduction theory is their generality, which makes them applicable in a wide range of settings

On Games and Computation

We introduce and investigate a range of general notions of a game. Our principal notion is based on a set of agents modifying a relational structure in a discrete evolution sequence. We also introduce and study a variety of ways to model incomplete and erroneous information in the setting. We discuss the connection of the related general setting to logic and computation formalisms, with emphasis on the recently introduced Turing-complete logic based on game-theoretic semantics

Caritas and Ren: a comparative study of Thomas Aquinas and Zhu Xi in the contexts of their traditions

The thesis is a comparison of Chinese and Western, Confucian and Christian, ideas and values. Its central focus is on caritas as the primary Christian virtue, and ren (benevolence) as the primary Confucian virtue. The comparison deals eventually with the way in which these virtues are read by Aquinas and xhu Xi, and situated within their philosophies as a whole. Aquinas and Zhu Xi are in read in relation to their traditions, in order to identify the tensions and presuppositions that are incorporated in their work. Attention is also given to the problems of reading Historical texts, and texts from different cultural traditions, both in terms of the hermeneutic issues at work in such reading, and the possible significance that such reading might have for contemporary culture

Italia Conquistata: The Role of Italy in Milton’s Early Poetic Development

My thesis explores the way in which the Italian language and literary culture contributed to John Milton’s early development as a poet (over the period up to 1639 and the composition of Epitaphium Damonis). I begin by investigating the nature of the cultural relationship between England and Italy in the late medieval and early modern periods. I then examine how Milton’s own engagement with the Italian language and its literature evolved in the context of his family background, his personal contacts with the London Italian community and modern language teaching in the early seventeenth century as he grew to become a ‘multilingual’ poet. My study then turns to his first published collection of verse, Poems 1645. Here, I reconsider the Italian elements in Milton’s early poetry, beginning with the six poems he wrote in Italian, identifying their place and significance in the overall structure of the volume, and their status and place within the Italian Petrarchan verse tradition. After considering the significance of the Italian titles of L’Allegro and Il Penseroso, I assess the impact of Italian verse forms (and particularly the canzone) upon Milton’s early poetry in English and the question of the nature of the relationship between Milton’s Mask presented at Ludlow Castle and Tasso’s ‘favola boschereccia’, Aminta. Finally, I consider the place in Milton’s career of his journey to Italy in 1938-9 and its importance to him as a personal ‘conquest’ of Italy. I suggest that, far from setting him upon the path toward poetic glory, as is often claimed, his return England marked the beginning of a lengthy hiatus in his poetic career. My argument is that Milton was much more Italianate, by background, accident of birth and personal bent, than has usually been recognised and that an appreciation of how this Italian aspect of his cultural identity contributed to his poetic development is central to an understanding of his poetry