We consider different ways of describing a matroid to a Turing machine by listing the members of various families of subsets, and we construct an order on these different methods of description. We show that, under this scheme, several natural matroid problems are complete in classes thought not to be equal to P. We list various results linking parameters of basis graphs to parameters of their associated matroids. For small values of k we determine which matroids have the clique number, chromatic number, or maximum degree of their basis graphs bounded above by k. If P is a class of graphs that is closed under isomorphism and induced subgraphs, then the set of matroids whose basis graphs belong to P is closed under minors. We characterise the minor-closed classes that arise in this way, and exhibit several examples. One way of choosing a basis of a matroid at random is to select a total ordering of the ground set uniformly at random and use the greedy algorithm. We consider the class of matroids having the property that this procedure chooses a basis uniformly at random. Finally we consider a problem mentioned by Oxley. He asked if, for every two elements and n - 2 cocircuits in an n-connected matroid, there is a circuit that contains both elements and that meets every cocircuit. We show that a slightly stronger property holds for regular matroids.

The price of anarchy, a concept introduced by Koutsoupias and Papadimitriou [9], is the main topic of this thesis. It is a measure of the loss of efficiency that occurs when there is no central control over a system consisting of many "selfish" agents. We will be particularly interested in this in the context of network games, which can be used to model congestion in traffic and communication networks. / After an introduction of the relevant concepts and review of related work, we proceed with the new results of this thesis. We provide a new upper bound for the price of anarchy in the case of atomic unsplittable agents with polynomial cost functions, and demonstrate that it is tight by an explicit construction. We then introduce a new model for network routing that introduces priorities; users with a higher priority on a link will be able to traverse the link more quickly. Our model is fairly general, and allows various different priority schemes for modelling different situations. One particularly interesting version, which we have dubbed the timestamp game, assigns priorities according to the order of arrival at the start of the link. / We derive tight upper bounds for the price of anarchy in our model in the case of polynomial cost functions and nonatomic agents. We also obtain tight results in the unsplittable case with linear cost functions, and an upper bound with polynomial cost functions. / While we concentrate on network games, most of the results carry through to the more general class of congestion games, which we also discuss.

Cognitive complexity mitigation strategies are methods and approaches utilized by users to reduce the apparent complexity of problems thus making them easier to solve. These strategies often effective because they mitigate the limitations of human working memory and attention resources. Such cognitive complexity mitigation strategies are used throughout the design, development and operational processes of complex systems. Thus, a better understanding of these strategies, and methods that leverage them, can help improve the efficiency of such processes. Additionally, changes in the use of these strategies across various environments can identify cognitive differences in operating and developing across these contexts. This knowledge can help improve the effectiveness of cross-context user transfers by suggesting change management processes that incorporate the degree of cognitive difference across contexts. In order to document cognitive complexity mitigation strategies and the change in their usage, two application domains are studied. Firstly, cognitive complexity mitigation strategies used by designers during the engineering design process are found through an ethnographic immersion with a participating engineering firm, followed by an analysis of the designer's logbooks and validation interviews with the designers. Results include identification of five strategies used by the designers to mitigate design complexity. These strategies include Blackbox Modeling, Whitebox Modeling, Decomposition, Visualization and Prioritized Lists. The five complexity mitigation strategies are probed further across a larger sample of engineering designers and the usage frequency of these strategies is assessed across commonly performed engineering design activities which include the Selection, Configuration and Parametric activities. The results indicate the preferred use of certain strategies based on the engineering activity being performed. Such preferential usage of complexity mitigation strategies is also assessed with regards to Original and Redesign projects types. However, there is no indication of biased strategy usage across these two project characterizations. These results are an example of a usage-frequency based difference analysis; such analyses help identify the strategies that experience increased or reduced usage when transferring across activities. In contrast to the first application domain, which captures changes in how often strategies are used across contexts, the second application domain is a method of assessing differences based on how a specific strategy is used differently across contexts. This alternative method is developed through a project that aims to optimize the transfer of air traffic controllers across different airspace sectors. The method uses a previously researched complexity mitigation strategy, knows as a structure based abstraction, to develop a difference analysis tool called the Sector Abstraction Binder. This tool is used to perform cognitive difference analyses between air traffic control sectors by leveraging characteristic variations in how structure based abstractions are applied across different sectors. This Sector Abstraction Binder is applied to two high-level airspace sectors to demonstrate the utility of such a method.

Previous cultural research found that East Asian pictorial representations (e.g., paintings) contained more elements than North American ones, and that East Asians were more likely than North Americans to prefer context-rich information to context-impoverished information (Miyamoto, Nisbett, & Masuda, 2006; Masuda, Gonzalez, Kwan, & Nisbett, 2008). Four studies were conducted to examine the cultural variations of the complexity difference between East Asians and North Americans. Study 1 analyzed the posters collected at the SPSP conference and the results indicated that East Asians were more likely than North Americans to design complex posters when posters contained two or more studies; however, no cultural effect was found when posters contained a single study. In Study 2, I analyzed portal pages of governments and universities in East Asian (e.g., China, Japan, Korea) and North American societies (e.g., USA and Canada), and found that East Asian portal pages were more complex than North American ones. Based on the findings, I further investigated peoples speed in dealing with complex web information in Study 3 and simple web information in Study 4. The results showed that East Asians were faster than North Americans in dealing with information on complex WebPages, especially at the bottom of sections, but no cultural effect was found when participants were asked to perform the same tasks on simple WebPages. This research reinforced the previous cultural research on visual representations, and suggested that East Asians were more likely than North Americans to prefer to complex designs, which in turn can affect peoples patterns of attention and cognition. (255 words)

Research Doctorate - Doctor of Philosophy (PhD) / Gendered labour market inequalities are a key area of feminist enquiry. Current approaches to theorising labour market inequalities usually conceive agentic social action and existing social structures as opposing forces, rather than as highly complex interwoven levels of social reality, which together constitute and reconstitute labour market inequalities over time. Further, these analyses tend to privilege either the social construction of gender or the different material circumstances of women’s lives in their accounts, inadequately addressing interfaces between ‘gender’ and the ‘material’. This study attempts to integrate these facets and levels of social reality more closely, offering an alternative account of how gendered labour market inequalities may be shored up or destablised over time. It builds on innovative work outside the field of labour market studies to do so. While the key existing accounts of labour market inequalities offer quite diverse explanations for these inequalities, gendered marital power relations and child-raising responsibilities, along with gendered patterns of participation in, and outcomes from, education and paid work are prominent features of them all. To acknowledge this prior research and some of its insights, analysis of the ‘transitions’ young women are currently making in these domains is a central feature of this study. In doing so, I acknowledge the wealth of research and debate on the late modern fracturing of youth to ‘adult’ transitions, and the future social changes these imply. I further suggest that disruptions and continuities in the forms of education, work, parenting and relationships that young Australian women aspire to, along with shifts in the timing and form of these transitions, have important potential implications for the maintenance or destabilisation of existing broader labour market inequalities over time. The alternative account offered here is developed by drawing on data gathered through a mixed methods study design, incorporating qualitative interviews and survey responses from groups of high SES and low SES young Australian women. Young women’s accounts of their aspirations for parenting, partnering, education and work, are treated using discursive analysis of the interview texts and comparison of these findings with descriptive statistics generated from the survey results. Theoretically, this analysis is guided by feminist poststructuralist notions of discourse, subject positioning and subjectivity. However, these poststructuralist concepts are reconciled with a notion of socio-cultural capital as a resource, developed to allow a ‘materialist’ edge in the empirical analyses. Additionally, insights from complexity thought provide a means for this study to conceive of the relationships between macro social structures and micro social processes as co-producing the labour market inequalities that the study addresses. The thesis of this study is that the social construction of gender, the material circumstances of women’s lives, and their agentic negotiations with these, are critical and interactive features of an adequate account of the processes through which labour market inequalities are shored up or destabilised over time. I suggest that the synthesised theoretical framework developed and presented here may be highly effective for this task. The contribution of the study is therefore fourfold. Firstly, it provides a snapshot of the transitions young Australian women with different material circumstances are making into relationships and parenting, education and work. Secondly, it offers novel insights into the processes through which labour market inequalities may be maintained or not. Thirdly, it offers an integrated account of the interplay between discursive/cultural and material/economic social forces in producing these inequalities. Finally, it augments existing scholarship by introducing an innovative theoretical synthesis to the study of labour market inequalities.

Thesis (Ph. D.)--University of North Texas, Aug., 2007. / Title from title page display. Includes bibliographical references.

Univ., Habil.-Schr--Zürich. / Literaturverz. S. [149] - 157.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (p. [155]-167).

Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: private-key cryptography; Advanced Encryption Standard; K-secure; hermetic; block cipher; circuit complexity. Includes bibliographical references (p. 75-79).

Thesis (Th. M.)--Calvin Theological Seminary, 1995. / Abstract. Includes bibliographical references (leaves 189-200).