2,383 research outputs found

    Thue's 1914 paper: a translation

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    This paper includes notes to accompany a reading of Thue's 1914 paper "Probleme uber Veranderungen von Zeichenreihen nach gegebenen Reglen", along with a translation of that paper. Thue's 1914 paper is mainly famous for proving an early example of an undecidable problem, cited prominently by Post. However, Post's paper principally makes use of the definition of Thue systems, described on the first two pages of Thue's paper, and does not depend on the more specific results in the remainder of Thue's paper. A closer study of the remaining parts of that paper highlight a number of important themes in the history of computing: the transition from algebra to formal language theory, the analysis of the "computational power" (in a pre-1936 sense) of rules, and the development of algorithms to generate rule-sets

    A Catholic Surgeon

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    In the palm of your hand: supporting rural teacher professional development and practice through the use of mobile phones and other handheld digital devices

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    Given the huge growth of mobile phone access in Sub Saharan Africa (Minges, 2004) some of the most innovative uses of mobile devices are now to be found in the development context (Economist, 2005). Reviews of the use of mobile technologies point to a range of current and potential development for learning in classrooms, homes and the community (e.g. Naismith et al). This paper draws on the experience of two projects: a large scale project for SMS mediated school administration in Kenya and a small scale research project using eBooks and other digital tools for teacher professional development and practice, carried out in predominantly rural schools in the Eastern Cape, South Africa. This research is set in the wider context of the emerging theory, practice and evaluation of the use of mobile technologies for improving teaching and learning (Leach 2006, Power & Thomas 2006, Traxler & Kukulska-Hulme 2006). The paper considers the potential of currently common mobile phones to aid communication and break down isolation amongst rural teachers and the design, use and evaluation of e-book learning resources on handheld mobile devices, such as current ‘smart-phones’, which the authors anticipate will soon be the ‘normal’ ubiquitous mobile phone. Whilst there is only a small body of evidence on the application of mobile technologies to teacher learning, impacts on teacher development remain a matter for debate. Findings suggest that given the right conditions, uses of mobile technology can significantly enhance teacher professional learning and practice

    Metamodel Instance Generation: A systematic literature review

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    Modelling and thus metamodelling have become increasingly important in Software Engineering through the use of Model Driven Engineering. In this paper we present a systematic literature review of instance generation techniques for metamodels, i.e. the process of automatically generating models from a given metamodel. We start by presenting a set of research questions that our review is intended to answer. We then identify the main topics that are related to metamodel instance generation techniques, and use these to initiate our literature search. This search resulted in the identification of 34 key papers in the area, and each of these is reviewed here and discussed in detail. The outcome is that we are able to identify a knowledge gap in this field, and we offer suggestions as to some potential directions for future research.Comment: 25 page

    Coalgebraic Semantics for Timed Processes

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    We give a coalgebraic formulation of timed processes and their operational semantics. We model time by a monoid called a “time domain”, and we model processes by “timed transition systems”, which amount to partial monoid actions of the time domain or, equivalently, coalgebras for an “evolution comonad ” generated by the time domain. All our examples of time domains satisfy a partial closure property, yielding a distributive law of a monad for total monoid actions over the evolution comonad, and hence a distributive law of the evolution comonad over a dual comonad for total monoid actions. We show that the induced coalgebras are exactly timed transition systems with delay operators. We then integrate our coalgebraic formulation of time qua timed transition systems into Turi and Plotkin’s formulation of structural operational semantics in terms of distributive laws. We combine timing with action via the more general study of the combination of two arbitrary sorts of behaviour whose operational semantics may interact. We give a modular account of the operational semantics for a combination induced by that of each of its components. Our study necessitates the investigation of products of comonads. In particular, we characterise when a monad lifts to the category of coalgebras for a product comonad, providing constructions with which one can readily calculate. Key words: time domains, timed transition systems, evolution comonads, delay operators, structural operational semantics, modularity, distributive laws
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