Thinking about Attention in Games: Backward and Forward Induction

Behavioral economics improves economic analysis by using psychological regularity to suggest limits on rationality and self-interest (e.g. Camerer and Loewenstein 2003). Expressing these regularities in formal terms permits productive theorizing, suggests new experiments, can contribute to psychology, and can be used to shape economic policies which make normal people better off

A secular increase in continental crust nitrogen during the Precambrian

Recent work indicates the presence of substantial geologic nitrogen reservoirs in the mantle and continental crust. Importantly, this geologic nitrogen has exchanged between the atmosphere and the solid Earth over time. Changes in atmospheric nitrogen (i.e. atmospheric mass) have direct effects on climate and biological productivity. It is difficult to constrain, however, the evolution of the major nitrogen reservoirs through time. Here we show a secular increase in continental crust nitrogen through Earth history recorded in glacial tills (2.9 Ga to modern), which act as a proxy for average upper continental crust composition. Archean and earliest Palaeoproterozoic tills contain 66 $\pm$ 100 ppm nitrogen, whereas Neoproterozoic and Phanerozoic tills contain 290 $\pm$ 165 ppm nitrogen, whilst the isotopic composition has remained constant at ~4\permil. Nitrogen has accumulated in the continental crust through time, likely sequestered from the atmosphere via biological fixation. Our findings support dynamic, non-steady state behaviour of nitrogen through time, and are consistent with net transfer of atmospheric N to geologic reservoirs over time.Comment: 14 pages, 2 figures, 2 tables, supplemental informatio

Using tabu search and genetic algorithms in mathematics research

This paper discusses an ongoing project which uses computational heuristic search techniques such as tabu search and genetic algorithms as a tool for mathematics research. We discuss three ways in which such search techniques can be useful for mathematicians: in nding counterexamples to conjectures, in enumerating examples, and in nding sequences of transformations between two objects which are conjectured to be related. These problem-types are discussed using examples from topology

Towards a methodology for rigorous development of generic requirements patterns

We present work in progress on a methodology for the engineering, validation and verification of generic requirements using domain engineering and formal methods. The need to develop a generic requirement set for subsequent system instantiation is complicated by the addition of the high levels of verification demanded by safety-critical domains such as avionics. We consider the failure detection and management function for engine control systems as an application domain where product line engineering is useful. The methodology produces a generic requirement set in our, UML based, formal notation, UML-B. The formal verification both of the generic requirement set, and of a particular application, is achieved via translation to the formal specification language, B, using our U2B and ProB tools

The Nitrogen Budget of Earth

We comprehensively compile and review N content in geologic materials to calculate a new N budget for Earth. Using analyses of rocks and minerals in conjunction with N-Ar geochemistry demonstrates that the Bulk Silicate Earth (BSE) contains \sim7\pm4 times present atmospheric N (4\times10^18 kg N, PAN), with 27\pm16\times10^18 kg N. Comparison to chondritic composition, after subtracting N sequestered into the core, yields a consistent result, with BSE N between 17\pm13\times10^18 kg to 31\pm24\times10^18 kg N. In the chondritic comparison we calculate a N mass in Earth's core (180\pm110 to 300\pm180\times10^18 kg) and discuss the Moon as a proxy for the early mantle. Significantly, we find the majority of the planetary budget of N is in the solid Earth. The N estimate herein precludes the need for a "missing N" reservoir. Nitrogen-Ar systematics in mantle rocks and basalts identify two mantle reservoirs: MORB-source like (MSL) and high-N. High-N mantle is composed of young, N-rich material subducted from the surface and is identified in OIB and some xenoliths. In contrast, MSL appears to be made of old material, though a component of subducted material is evident in this reservoir as well. Using our new budget, we calculate a {\delta}15N value for BSE plus atmosphere of \sim2\permil. This value should be used when discussing bulk Earth N isotope evolution. Additionally, our work indicates that all surface N could pass through the mantle over Earth history, and the mantle may act as a long-term sink for N. Since N acts as a tracer of exchange between the atmosphere, oceans, and mantle over time, clarifying its distribution in the Earth is critical for evolutionary models concerned with Earth system evolution. We suggest that N be viewed in the same vein as carbon: it has a fast, biologically mediated cycle which connects it to a slow, tectonically-controlled geologic cycle.Comment: Manuscript accepted in Earth Science Review

Is it Time for Computational Creativity to Grow Up and Start being Irresponsible?

A recent definition of computational creativity has em- phasised that computational creativity systems should “take on certain responsibilities” for generating creative behaviour. This paper examines the notion of responsibilities in that definition, and looks at a number of aspects of the creative act and its context that might play a role in that responsibility, with an emphasis on artistic and musical creativity. This problematises the seemingly simple distinction between systems that have responsibilities for creative activity and those which support or provide tools for creativity. The paper con- cludes with a discussion of an alternative approach to the subject, which argues that the responsibility for creative action is typically diffused through a complex human/computer system, and that a “systems thinking” approach to locating computational creativity might ask better questions than one that tries to pin creative responsibility to a particular agent

A new sequential covering strategy for inducing classification rules with ant colony algorithms

Ant colony optimization (ACO) algorithms have been successfully applied to discover a list of classification rules. In general, these algorithms follow a sequential covering strategy, where a single rule is discovered at each iteration of the algorithm in order to build a list of rules. The sequential covering strategy has the drawback of not coping with the problem of rule interaction, i.e., the outcome of a rule affects the rules that can be discovered subsequently since the search space is modified due to the removal of examples covered by previous rules. This paper proposes a new sequential covering strategy for ACO classification algorithms to mitigate the problem of rule interaction, where the order of the rules is implicitly encoded as pheromone values and the search is guided by the quality of a candidate list of rules. Our experiments using 18 publicly available data sets show that the predictive accuracy obtained by a new ACO classification algorithm implementing the proposed sequential covering strategy is statistically significantly higher than the predictive accuracy of state-of-the-art rule induction classification algorithms

Camp Life: The Queer History of Manhood in the Civilian Conservation Corps, 1933-1937

Between 1933 and 1942 hundreds of thousands of young American men sought relief from the poverty and hopelessness of the Great Depression by joining FDR’s Emergency Work Relief program, otherwise known as the Civilian Conservation Corps. Although the Corps attracted men from both town and country, the vast majority of work camps to which It sent enrollees were located near small towns or in remote rural areas far from US urban centers. This essay explores the homosocial world of these camps paying particularly close attention to the traditions of gender-bending drag performance and homoerotic innuendo that grew up within them. Following the invitation of Martin Bauml Duberman, who first suggested in 1981 that the CCC might prove to be a worthy subject of inquiry for historians of the gay past, the essay argues that in the organization’s early years especially camp life was, in fact, a camp life—one in which the very meaning of American manhood was constantly being challenged, contested and reworked in ways that bear a striking resemblance to the sometimes coded, sometimes openly flamboyant techniques of sociability typically associated with urban sexual subcultures during this period. As such, it makes a claim for the CCC’s importance as a crucial point of historical connection between the proto-gay subcultures that flourished in American cities during the early twentieth century and the homosexual subculture that arose in another federal entity—the US military—during the Second War World

Event-based graphical monitoring in the EpochX genetic programming framework

EpochX is a genetic programming framework with provision for event management – similar to the Java event model – allowing the notification of particular actions during the lifecycle of the evolutionary algorithm. It also provides a flexible Stats system to gather statistics measures. This paper introduces a graphical interface to the EpochX genetic programming framework, taking full advantage of EpochX's event management. A set of representation-independent and tree-dependent GUI components are presented, showing how statistic information can be presented in a rich format using the information provided by EpochX's Stats system