27,371 research outputs found
Prospects for large-scale financial systems simulation
No full textAs the 21st century unfolds, we find ourselves having to control, support, manage or otherwise cope with large-scale complex adaptive systems to an extent that is unprecedented in human history. Whether we are concerned with issues of food security, infrastructural resilience, climate change, health care, web science, security, or financial stability, we face problems that combine scale, connectivity, adaptive dynamics, and criticality. Complex systems simulation is emerging as the key scientific tool for dealing with such complex adaptive systems. Although a relatively new paradigm, it is one that has already established a track record in fields as varied as ecology (Grimm and Railsback, 2005), transport (Nagel et al., 1999), neuroscience (Markram, 2006), and ICT (Bullock and Cliff, 2004). In this report, we consider the application of simulation methodologies to financial systems, assessing the prospects for continued progress in this line of research
Competition and the dynamics of group affiliation
No full textHow can we understand the interaction between the social network topology of a population and the patterns of group affiliation in that population? Each aspect influences the other: social networks provide the conduits via which groups recruit new members, and groups provide the context in which new social ties are formed. From an organisational ecology perspective, groups can be considered to compete with one another for the time and energy of their members. Such competition is likely to have an impact on the way in which social structure and group affiliation co-evolve. While many social simulation models exhibit group formation as a part of their behaviour (e.g., opinion clusters or converged cultures), models that explicitly focus on group affiliation are rare. We describe and explore the behaviour of a model in which, distinct from most current models, individual nodes can belong to multiple groups simultaneously. By varying the capacity of individuals to belong to groups, and the costs associated with group membership, we explore the effect of different levels of competition on population structure and group dynamics
Spatial embedding as an enabling constraint: Introduction to a special issue of complexity on the topic of “Spatial Organisation”
No full textWe introduce and discuss the role of spatial embedding as an enabling constraint on complex system structure and function
W. F. Mitchell
No full textEarlier this year, an article was published in the News Bulletin
(February 2012) on the background of Captain Boyns Hedley
Hocking, a dentist who became one of the first casualties in the
bombing of Darwin in 1942. The author, W F Mitchell, has kindly
provided a summary of the 70th anniversary activities held in
Darwin in February 2012 to commemorate this significant event in
the Northern Territory?s historyDate:2012-09News Bulletin no. 413, p. 36 - 37
Assessing the George W. Bush Presidency: A Tale of Two Terms
No full textIn one of the first volumes assessing the full two terms of the George W. Bush presidency, Wroe and Herbert have gathered the work of leading American and European scholars. In fifteen succinct and incisive chapters, authorities such as Jim Pfiffner, John Maltese, Graham Wilson and Alan Gitelson offer assessments of the Bush administration's successes and failures. Extensive attention is paid to Bush's foreign policy, including 'The War on Terror' but the focus is broadened to absorb not only the Bush Doctrine and its repercussions, but also his trade and homeland security policies. The president's domestic leadership in economics and social policy is investigated, as are his dealings as president with the other institutions of the U.S. political system. The result is a comprehensive guide to the Bush presidency and its legacy
Exploring adaptation with evolutionary activity plots
No full textEvolutionary activity statistics and their visualization are introduced, and their motivation is explained. Examples of their use are described, and their strengths and limitations are discussed. References to more extensive or general accounts of these techniques are provided
Spatially embedded dynamics and complexity
No full textTo gain a deeper understanding of the impact of spatial embedding on the dynamics of complex systems we employ a measure of interaction complexity developed within neuroscience using the tools of statistical information theory. We apply this measure to a set of simple network models embedded within Euclidean spaces of varying dimensionality in order to characterise the way in which the constraints imposed by low-dimensional spatial embedding contribute to the dynamics (rather than the structure) of complex systems. We demonstrate that strong spatial constraints encourage high intrinsic complexity, and discuss the implications for complex systems in general
Levins and the lure of artificial worlds
No full textWhat is it about simulation models that has led some practitioners to treat them as potential sources of empirical data on the real-world systems being simulated; that is, to treat simulations as ‘artificial worlds’ within which to perform computational ‘experiments’? Here we use the work of Richard Levins as a starting point in identifying the appeal of this model building strategy, and proceed to account for why this appeal is strongest for computational modellers. This analysis suggests a perspective on simulation modelling that makes room for ‘artificial worlds’ as legitimate science without having to accept that they should be treated as sources of empirical dat
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