Modular Composition of Language Features through Extensions of Semantic Language Models

Today, programming or specification languages are often extended in order to customize them for a particular application domain or to refine the language definition. The extension of a semantic model is often at the centre of such an extension. We will present a framework for linking basic and extended models. The example which we are going to use is the RSL concurrency model. The RAISE specification language RSL is a formal wide-spectrum specification language which integrates different features, such as state-basedness, concurrency and modules. The concurrency features of RSL are based on a refinement of a classical denotational model for process algebras. A modification was necessary to integrate state-based features into the basic model in order to meet requirements in the design of RSL. We will investigate this integration, formalising the relationship between the basic model and the adapted version in a rigorous way. The result will be a modular composition of the basic process model and new language features, such as state-based features or input/output. We will show general mechanisms for integration of new features into a language by extending language models in a structured, modular way. In particular, we will concentrate on the preservation of properties of the basic model in these extensions

The Impact of Alan Turing: Formal Methods and Beyond

© 2019, Springer Nature Switzerland AG. In this paper, we discuss the influence and reputation of Alan Turing since his death in 1954, specifically in the field of formal methods, especially for program proving, but also in a much wider context. Although he received some recognition during his lifetime, this image was tarnished by the controversy at the time of his death. While he was known and appreciated in scientific circles, he did not enter the public’s consciousness for several decades. A turning point was the definitive biography produced by Andrew Hodges in 1983 but, even then, the tide did not turn very rapidly. More recent events, such as the celebrations of his birth centenary in 2012 and the official British royal pardon in 2013, have raised Turing’s fame and popularity among the informed general public in the United Kingdom and elsewhere. Cultural works in the arts featuring Turing have enhanced his profile still further. Thus, the paper discusses not only Turing’s scientific impact, especially for formal methods, but in addition his historical, cultural, and even political significance. Turing’s academic ‘family tree’ in terms of heritage and legacy is also covered

Reflective teaching and disruptive behaviour in regular high school classrooms in London, Engand

Despite conflicting reports on the state of disruptive behaviour in schools it continues to be a perennial one for all teachers. The purpose of this self-study, which utilises personal experience stories in the form of vignettes taken from my experience of teaching in various high schools in London England, is to illustrate how teaching reflectively can result in the reinforcement of practical or work-related knowledge regarding the utilisation of appropriate behavioural management strategies in local schools. Although the study is limited to classrooms in England, disruptive behaviour is a world-wide occurrence therefore it has potential relevance for educators in other countries

UTP, Circus, and Isabelle

We dedicate this paper with great respect and friendship to He Jifeng on the occasion of his 80th birthday. Our research group owes much to him. The authors have over 150 publications on unifying theories of programming (UTP), a research topic Jifeng created with Tony Hoare. Our objective is to recount the history of Circus (a combination of Z, CSP, Dijkstra’s guarded command language, and Morgan’s refinement calculus) and the development of Isabelle/UTP. Our paper is in two parts. (1) We first discuss the activities needed to model systems: we need to formalise data models and their behaviours. We survey our work on these two aspects in the context of Circus. (2) Secondly, we describe our practical implementation of UTP in Isabelle/HOL. Mechanising UTP theories is the basis of novel verification tools. We also discuss ongoing and future work related to (1) and (2). Many colleagues have contributed to these works, and we acknowledge their support

The Pragmatics of Virtual Environments. Compliment responses in Second Life

ENThe advent of the Internet has dramatically changed, among other things, the way people learn a language. With the new ICT tools, more and more users can interact with native speakers in their target language, potentially without ever moving from home. To this regard, virtual worlds appear to be a resourceful place where language learners can meet and practice their L2. However, while these virtual worlds are being increasingly employed for language learning purposes, they still remain a linguistically unexplored ground. But if the Internet has changed the way people interact, it is also plausible that the pragmatic norms underlying this new form of communication have changed; therefore understanding their literacy would help understand their efficacy too. This study sets out to fill a gap in the literature by looking at how compliments are responded in Second Life. The results are then compared with compliment responses in real life to find out whether the language used in virtual environments faithfully reproduces the language used in face-to-face conversation, and to what extent it is convenient and significant for instructors to integrate such environments in their teaching practices. The results show a greater tendency to accept compliments than in real-life conversation. Possible pedagogical implications and directions for further research are discussed.Keywords: pragmatics; compliment responses; virtual environments; language learningITL’avvento di internet ha radicalmente cambiato, tra le altre cose, il modo in cui le persone imparano una lingua. Con i nuovi mezzi ICT, sempre più utenti possono interagire con parlanti nativi nella lingua d’arrivo, senza potenzialmente mai muoversi da casa. A questo riguardo/In questo ambito, i mondi virtuali sembrano essere un luogo pieno di risorse dove gli apprendenti di una lingua possono incontrarsi e praticare l’L2. Tuttavia, mentre questi mondi virtuali vengono sempre più utilizzati per l’apprendimento linguistico, rimangono ancora un terreno linguisticamente inesplorato. Ma se internet ha cambiato il modo in cui la gente interagisce, è anche plausibile che le norme sottostanti questa nuova forma di comunicazione siano cambiate; pertanto comprenderne il funzionamento aiuterebbe a comprenderne anche l’efficacia. Questo studio si propone di colmare un vuoto nella letteratura osservando come si risponde ai complimenti su Second Life. I risultati sono poi confrontati con le risposte ai complimenti nella conversazione reale per capire se la lingua usata negli ambienti virtuali riproduce fedelmente la lingua utilizzata nella conversazione faccia a faccia, e fino a che punto è conveniente e significativo per gli insegnanti integrare tali ambienti nelle pratiche d’insegnamento. I risultati mostrano una tendenza maggiore ad accettare i complimenti rispetto alla conversazione reale. Possibili implicazioni pedagogiche e indicazioni per ricerche future sono prese in considerazione.Parole chiave: pragmatica; risposte ai complimenti; ambienti virtuali; apprendimento linguistic

Dash: declarative behavioural modelling in Alloy with control state hierarchy

This is a post-peer-review, pre-copyedit version of an article published in Software and Systems Modeling. The final authenticated version is available online at: https://doi.org/10.1007/s10270-022-01012-1We present Dash, an extension to the Alloy language to model dynamic behaviour using the labelled control state hierarchy of Statecharts. From Statecharts, Dash borrows the concepts to specify hierarchy, concurrency, and communication for describing behaviour in a compositional manner. From Alloy, Dash uses the expressiveness of relational logic and set theory to abstractly and declaratively describe structures, data, and operations. We justify our semantic design decisions for Dash, which carefully mix the usual semantic understanding of control state hierarchy with the declarative perspective. We describe and implement the semantics of a Dash model by translating it to Alloy, taking advantage of Alloy language features. We evaluate our Dash translation and perform model checking analysis, enabled by our translation, in the Alloy Analyzer using several case studies. Dash provides modellers with a language that seamlessly combines the semantics of control-modelling paradigms with Alloy’s existing strengths in modelling data and operations abstractly

On the mechanisation of the logic of partial functions

PhD ThesisIt is well known that partial functions arise frequently in formal reasoning about programs. A partial function may not yield a value for every member of its domain. Terms that apply partial functions thus may not denote, and coping with such terms is problematic in two-valued classical logic. A question is raised: how can reasoning about logical formulae that can contain references to terms that may fail to denote (partial terms) be conducted formally? Over the years a number of approaches to coping with partial terms have been documented. Some of these approaches attempt to stay within the realm of two-valued classical logic, while others are based on non-classical logics. However, as yet there is no consensus on which approach is the best one to use. A comparison of numerous approaches to coping with partial terms is presented based upon formal semantic definitions. One approach to coping with partial terms that has received attention over the years is the Logic of Partial Functions (LPF), which is the logic underlying the Vienna Development Method. LPF is a non-classical three-valued logic designed to cope with partial terms, where both terms and propositions may fail to denote. As opposed to using concrete undfined values, undefinedness is treated as a \gap", that is, the absence of a defined value. LPF is based upon Strong Kleene logic, where the interpretations of the logical operators are extended to cope with truth value \gaps". Over the years a large body of research and engineering has gone into the development of proof based tool support for two-valued classical logic. This has created a major obstacle that affects the adoption of LPF, since such proof support cannot be carried over directly to LPF. Presently, there is a lack of direct proof support for LPF. An aim of this work is to investigate the applicability of mechanised (automated) proof support for reasoning about logical formulae that can contain references to partial terms in LPF. The focus of the investigation is on the basic but fundamental two-valued classical logic proof procedure: resolution and the associated technique proof by contradiction. Advanced proof techniques are built on the foundation that is provided by these basic fundamental proof techniques. Looking at the impact of these basic fundamental proof techniques in LPF is thus the essential and obvious starting point for investigating proof support for LPF. The work highlights the issues that arise when applying these basic techniques in LPF, and investigates the extent of the modifications needed to carry them over to LPF. This work provides the essential foundation on which to facilitate research into the modification of advanced proof techniques for LPF.EPSR

A Framework for the Analysis and User-Driven Evaluation of Trust on the Semantic Web

This project will examine the area of trust on the Semantic Web and develop a framework for publishing and verifying trusted Linked Data. Linked Data describes a method of publishing structured data, automatically readable by computers, which can linked to other heterogeneous data with the purpose of becoming more useful. Trust plays a significant role in the adoption of new technologies and even more so in a sphere with such vast amounts of publicly-created data. Trust is paramount to the effective sharing and communication of tacit knowledge (Hislop, 2013). Up to now, the area of trust in Linked Data has not been adequately addressed, despite the Semantic Web stack having included a trust layer from the very beginning (Artz and Gil, 2007). Some of the most accurate data on the Semantic Web lies practically unused, while some of the most used linked data has high numbers of errors (Zaveri et al., 2013). Many of the datasets and links that exist on the Semantic Web are out of date and/or invalid and this undermines the credibility and validity, and ultimately, the trustworthiness of both the dataset and the data provider (Rajabi et al., 2012). This research will examine a number of datasets to determine the quality metrics that a dataset is required to meet to be considered ‘trusted’. The key findings will be assessed and utilized in the creation of a learning tool and a framework for creating trusted Linked Data