Computing and Information Systems - Research Publications
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ItemLightweight Nontermination Inference with CHCs(SPRINGER INTERNATIONAL PUBLISHING AG, 2021)Non-termination is an unwanted program property (considered a bug) for some software systems, and a safety property for other systems. In either case, automated discovery of preconditions for non-termination is of interest. We introduce NtHorn, a fast lightweight non-termination analyser, able to deduce non-trivial sufficient conditions for non-termination. Using Constrained Horn Clauses (CHCs) as a vehicle, we show how established techniques for CHC program transformation and abstract interpretation can be exploited for the purpose of non-termination analysis. NtHorn is comparable in power to the state-of-the-art non-termination analysis tools, as measured on standard competition benchmark suites (consisting of integer manipulating programs), while typically solving problems an order of magnitude faster.
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ItemDisjunctive Interval Analysis(SPRINGER INTERNATIONAL PUBLISHING AG, 2021)We revisit disjunctive interval analysis based on the Boxes abstract domain. We propose the use of what we call range decision diagrams (RDDs) to implement Boxes, and we provide algorithms for the necessary RDD operations. RDDs tend to be more compact than the linear decision diagrams (LDDs) that have traditionally been used for Boxes. Representing information more directly, RDDs also allow for the implementation of more accurate abstract operations. This comes at no cost in terms of analysis efficiency, whether LDDs utilise dynamic variable ordering or not. RDD and LDD implementations are available in the Crab analyzer, and our experiments confirm that RDDs are well suited for disjunctive interval analysis.
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ItemNavigating Online Down Under: International Students’ Digital Journeys in Australia(Rowman & Littlefield, 2018)Research focusing on the experiences of international students tends to centre directly on their educational experiences rather than their everyday lives outside study. Moreover, much of this research has concentrated almost exclusively on the various impacts of the physical, geographic mobility of international students as they move from one country to another, with very little exploration of their digital experiences. There also exists extensive research on the social media and information seeking experiences of young people in different regions of the world. Some of this research provides a comparison between different sources of information and uses of social media. However, there has been little research on what happens when young people move between regions or countries. Borrowing Chang and Gomes’ (2017a) concept of the digital journey, where in crossing transnational borders, migrants might also cross digital borders, this chapter provides some concrete examples of the digital experiences of international students as they transition––wholly or partly––to the Australian digital environment. How do international students transition from certain online environments into others that may be completely different, even alien, to what they have previously experienced? Referring to qualitative and quantitative data collected from three separate projects conducted between 2012 and 2017, this chapter shows that in making the digital journey, international students in Australia do not so much quit their original digital comfort zones as widen their digital horizons. Understanding international students’ digital journeys is particularly significant since it has implications for future research in international student well-being and the provision of support services for students.
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ItemNo Preview AvailableWhy Young Children Don’t Play: Parents’ Accounts of Non-engagement with Digital Games(Cambridge Scholars Publishing, 2019)Focusing on the digital lives of children aged eight and under, and paying attention to their parents and educators, this book showcases research findings from the UK, Denmark, Turkey, Indonesia and Australia.
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Item"Adapt or Die": The funeral trade show as a site of institutional anxiety(Routledge, 2019-06-11)Funeral directors shot themselves in the foot over cremation, and cemeteries got splattered with the blood.
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ItemAutomating Digital Afterlives(Oxford University Press, 2021-08-26)The question of how the dead “live on” by maintaining a presence and connecting to the living within social networks has garnered the attention of users, entrepreneurs, platforms, and researchers alike. In this chapter we investigate the increasingly ambiguous terrain of posthumous connection and disconnection by focusing on a diverse set of practices implemented by users and offered by commercial services to plan for and manage social media communication, connection, and presence after life. Drawing on theories of self-presentation (Goffman) and technological forms of life (Lash), we argue that moderated and automated performances of posthumous digital presence cannot be understood as a continuation of personal identity or self-presentation. Rather, as forms of mediated human (after)life, posthumous social media presence materializes ambiguities of connection/disconnection and self/identity.
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ItemNo Preview Available6. Silenced by Power: Repression, Isolation & Persecution(transcript Verlag, 2021-12-03)
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ItemNo Preview AvailableModelling the Economic Impacts of Epidemics in Developing Countries Under Alternative Intervention Strategies(Springer, 2020)Modern levels of global travel have intensified the risk of new infectious diseases becoming pandemics. Particularly at risk are developing countries whose health systems may be less well equipped to detect quickly and respond effectively to the importation of new infectious diseases. This chapter examines what might have been the economic consequences if the 2014 West African Ebola epidemic had been imported to a small Asia-Pacific country. Hypothetical outbreaks in two countries were modelled. The post-importation estimations were carried out with two linked models: a stochastic disease transmission (SEIR) model and a quarterly version of the multi-country GTAP model, GTAP-Q. The SEIR model provided daily estimates of the number of persons in various disease states. For each intervention strategy the stochastic disease model was run 500 times to obtain the probability distribution of disease outcomes. Typical daily country outcomes for both controlled and uncontrolled outbreaks under five alternative intervention strategies were converted to quarterly disease-state results, which in turn were used in the estimation of GTAP-Q shocks to country-specific health costs and labour productivity during the outbreak, and permanent reductions in each country’s population and labour force due to mortality. Estimated behavioural consequences (severe reductions in international tourism and crowd avoidance) formed further shocks. The GTAP-Q simulations revealed very large economic costs for each country if they experienced an uncontrolled Ebola outbreak, and considerable economic costs for controlled outbreaks in Fiji due to the importance of the tourism sector to its economy. A major finding was that purely reactive strategies had virtually no effect on preventing uncontrolled outbreaks, but pre-emptive strategies substantially reduced the proportion of uncontrolled outbreaks, and in turn the economic and social costs.
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ItemSocial Planning for Trusted Autonomy(Springer International Publishing, 2018)In this chapter, we describe social planning mechanisms for constructing and representing explainable plans in human-agent interactions, addressing one aspect of what it will take to meet the requirements of a trusted autonomous system. Social planning is automated planning in which the planning agent maintains and reasons with an explicit model of the other agents, human or artificial, with which it interacts, including the humans’ goals, intentions, and beliefs, as well as their potential behaviours. The chapter includes a brief overview of the challenge of planning in human-agent teams, and an introduction to a recent body of technical work in multi-agent epistemic planning. The benefits of planning in the presence of nested belief reasoning and first-person multi-agent planning are illustrated in two scenarios, hence indicating how social planning could be used for planning human-agent interaction explicitly as part of an agent’s deliberation.
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ItemGuilt in DayZ(MIT Press, 2019-01-11)Death in most games is simply a metaphor for failure (Bartle 2010). Killing another player in a first-person shooter (FPS) game such as Call of Duty (Infinity Ward 2003) is generally considered to be as transgressive as taking an opponent’s pawn in chess. In an early exploratory study of players’ experiences and processing of violence in digital videogames, Christoph Klimmt and his colleagues concluded that “moral management does not apply to multiplayer combat games”(2006, 325). In other words, player killing is not a violation of moral codes or a source of moral concern for players. Subsequent studies of player experiences of guilt and moral concern in violent videogames (Hartmann, Toz, and Brandon 2010; Hartmann and Vorderer 2010; Gollwitzer and Melzer 2012) have consequently focused on the moral experiences associated with single-player games and the engagement with transgressive fictional, virtual narrative content.