422,196 research outputs found
Geometric lattice structure of covering and its application to attribute reduction through matroids
The reduction of covering decision systems is an important problem in data
mining, and covering-based rough sets serve as an efficient technique to
process the problem. Geometric lattices have been widely used in many fields,
especially greedy algorithm design which plays an important role in the
reduction problems. Therefore, it is meaningful to combine coverings with
geometric lattices to solve the optimization problems. In this paper, we obtain
geometric lattices from coverings through matroids and then apply them to the
issue of attribute reduction. First, a geometric lattice structure of a
covering is constructed through transversal matroids. Then its atoms are
studied and used to describe the lattice. Second, considering that all the
closed sets of a finite matroid form a geometric lattice, we propose a
dependence space through matroids and study the attribute reduction issues of
the space, which realizes the application of geometric lattices to attribute
reduction. Furthermore, a special type of information system is taken as an
example to illustrate the application. In a word, this work points out an
interesting view, namely, geometric lattice to study the attribute reduction
issues of information systems
Evolution in Economic Geography: Institutions, Regional Adaptation and Political Economy
Economic geography has, over the last decade or so, drawn upon ideas from
evolutionary economics in trying to understand processes of regional growth and
change, with the concept of path dependence assuming particular prominence.
Recently, some prominent researchers have sought to delimit and develop an
evolutionary economic geography (EEG) as a distinct approach, aiming to create a
more coherent and systematic theoretical framework for research. This paper
contributes to debates on the nature and development of EEG. It has two main aims.
First, we seek to restore a broader conception of social institutions and agency to
EEG, informed by the recent writings of institutional economists like Geoffrey
Hodgson. Second, we link evolutionary concepts to political economy approaches,
arguing that the evolution of the economic landscape must be related to the broader
dynamics of capital accumulation, centred upon the creation, realisation and
geographical transfer of value. As such, we favour the utilisation of evolutionary and
institutional concepts within a geographical political economy approach rather than
the construction of a separate and theoretically ‘pure’ EEG; evolution in economic
geography, not an evolutionary economic geography
Interactive Tutorials For Upper Level Quantum Mechanics Courses
This thesis explores the ongoing need for interactive tutorials in the upper level undergraduate Quantum Mechanics course. It first summarizes the development and evaluation of tutorials at the introductory physics level by others, and then challenges the belief that upper level students do not need this type of intervention by citing research in student difficulties in learning Quantum Mechanics. Physics Education research shows that there are common student misconceptions that persist even in the upper level undergraduate courses such as Quantum Mechanics. Cognitive research serves as a guide for effective curriculum design. A description of the iterative process for developing and evaluating the tutorials is discussed. The development and evaluation of "The Time Evolution of a Wave Function" Quantum Interactive Learning Tutorial (QuILT) is described in detail. Finally, the success of the QuILT in reducing the common misconceptions about time evolution is discussed
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Modeling software design diversity
Design diversity has been used for many years now as a means of achieving a degree of fault tolerance in software-based systems. Whilst there is clear evidence that the approach can be expected to deliver some increase in reliability compared with a single version, there is not agreement about the extent of this. More importantly, it remains difficult to evaluate exactly how reliable a particular diverse fault-tolerant system is. This difficulty arises because assumptions of independence of failures between different versions have been shown not to be tenable: assessment of the actual level of dependence present is therefore needed, and this is hard. In this tutorial we survey the modelling issues here, with an emphasis upon the impact these have upon the problem of assessing the reliability of fault tolerant systems. The intended audience is one of designers, assessors and project managers with only a basic knowledge of probabilities, as well as reliability experts without detailed knowledge of software, who seek an introduction to the probabilistic issues in decisions about design diversity
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Evaluating the resilience and security of boundaryless, evolving socio-technical Systems of Systems
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