We discuss linear and nonlinear boundary conditions for wave propagation problems. The concepts of well-posedness and stability are discussed by considering a specific example of a boundary condition occurring in the modeling of earthquakes. That boundary condition can be formulated in a linear and nonlinear way and implemented in a characteristic and non-characteristic way. These differences are discussed and the implications and difficulties are pointed out. Numerical simulations that illustrate the theoretical discussion are presented together with an application that show that the methodology can be used for practical problems.

As part of a larger study on the transition between upper secondary and tertiarymathematics education, this paper reports findings from an investigation of therelation between the students’ understanding of the criteria for legitimate mathematicalknowledge and their achievement during the first year in their undergraduatemathematics studies. As a methodology, we used interviews in whichengineering students were given excerpts from different, more or less formal,mathematics textbooks and asked whether they could rank these texts as being“more or less mathematical” and explain why. The results of our case studyindicate differences in the students’ views that are related to their achievement.

This book constitutes the refereed proceedings of the 5th International Conference on Network Optimization, INOC 2011, held in Hamburg, Germany, in June 2011. The 65 revised full papers presented were carefully reviewed and selected from numerous submissions. The papers highlight recent developments in network optimization and are organized in the following topical sections: theoretical problems, uncertainty, graph theory and network design; network flows; routing and transportation; and, further optimization problems and applications (energy oriented network design, telecom applications, location, maritime shipping, and graph theory).

Riemann surfaces is a thriving area of mathematics with applications to hyperbolic geometry, complex analysis, fractal geometry, conformal dynamics, discrete groups, geometric group theory, algebraic curves and their moduli, various kinds of deformation theory, coding, thermodynamic formalism, and topology of three-dimensional manifolds. This collection of articles, authored by leading authorities in the field, comprises 16 expository essays presenting original research and expert surveys of important topics related to Riemann surfaces and their geometry. It complements the body of recorded research presented in the primary literature by broadening, re-working and extending it in a more focused and less formal framework, and provides a valuable commentary on contemporary work in the subject. An introductory section sets the scene and provides sufficient background to allow graduate students and research workers from other related areas access to the field.

This book brings together 27 state-of-the-art research and review papers by leading experts and practitioners in mathematical methods in biomedical imaging, in intensity-modulated radiation therapy (IMRT) and in optimization and inverse problems. These papers were presented at the Huangguoshu International Interdisciplinary Conference on Biomedical Mathematics Promising Directions in Imaging, Therapy Planning, and Inverse Problems November 3 9, 2008 in China. The emphasis is on trying to discover relations and connections between these fields that will enhance progress in each of them. As this volume shows, applicable mathematical work in these fields goes hand-in-hand with real-world applications and the mutual technology transfers between them leads to further progress. The topics covered here include mathematical aspects and practical problems in current major and emerging technologies in diagnostic and therapeutic medicine and biology research. The contributed work signifies the interdisciplinary cooperation between mathematicians and scientists from medical physics, engineering, clinical medicine, and biology that leads to mathematically based better solutions of practical problems in biomedical imaging and IMRT.

Iceland, Denmark and contributions from Finland provides the first comprehensive and unified treatment of historical and contemporary research trends in mathematics education in the Nordic world. The book is organized in sections co-ordinated by active researchers in mathematics education in Norway, Sweden, Iceland, Denmark, and Finland. The purpose of this sourcebook is to synthesize and survey the established body of research in these countries with findings that have influenced ongoing research agendas, informed practice, framed curricula and policy. The sections for each country also include historical articles in addition to exemplary examples of recently conducted research oriented towards the future. The book will serve as a standard reference for mathematics education researchers, policy makers, practitioners and students both in and outside the Nordic countries. This Sourcebook includes over 50 chapters from the Nordic world. Section I- Norwegian Research in Mathematics Education Section Editor: Simon Goodchild Introduction to the Norwegian part of the Sourcebook of Nordic Research in Mathematics Education Simon Goodchild The development of mathematics education as a research field in Norway - an insider's personal reflections, Trygve Breiteig and Simon Goodchild Section II- Swedish Research in Mathematics Education Section Editor: Christer Bergsten Mathematics education research in Sweden - An introduction Christer Bergsten Some theoretical orientations of Swedish research Learning difficulties and mathematical reasoning Johan Lithner, Torulf Palm Section III - Icelandic Research in Mathematics Education Section Editors: Guðbjörg Pálsdóttir, Bharath Sriraman Mathematics Education in Iceland: Explaining the Non-homogeneity in a Homogenous System, Guðný Helga Gunnarsdóttir, Guðbjörg Pálsdóttir, Bharath Sriraman The History of Public Education in Mathematics in Iceland and its Relations to Secondary Education, Kristín Bjarnadóttir Section IV - Danish Research in Mathematics Education Section Editors: Bettina Dahl, Bharath Sriraman Section V- Contributions from Finland Section Editor: Lenni HaapasaloShow.

When unmanned aerial vehicles (UAVs) are used to survey distant targets, it is important to transmit sensor information back to a base station. As this communication often requires high uninterrupted bandwidth, the surveying UAV often needs afree line-of-sight to the base station, which can be problematic in urban or mountainous areas. Communication ranges may also belimited, especially for smaller UAVs. Though both problems can be solved through the use of relay chains consisting of one or more intermediate relay UAVs, this leads to a new problem: Where should relays be placed for optimum performance? We present two new algorithms capable of generating such relay chains, one being a dual ascent algorithm and the other a modification of the Bellman-Ford algorithm. As the priorities between the numberof hops in the relay chain and the cost of the chain may vary, wecalculate chains of different lengths and costs and let the ground operator choose between them. Several different formulations for edge costs are presented. In our test cases, both algorithms are substantially faster than an optimized version of the original Bellman-Ford algorithm, which is used for comparison.

The premise of the 15th ICMI Study is that teachers are key to students' opportunities to learn mathematics. What teachers of mathematics know, care about, and do is a product of their experiences and socialization, together with the impact of their professional education. The Professional Education and Development of Teachers of Mathematics assembles important new international work- development, research, theory and practice - concerning the professional education of teachers of mathematics. As it examines critical areas to reveal what is known and what significant questions and problems warrant collective attention, the volume also contributes to the strengthening of the international community of mathematics educators. The Professional Education and Development of Teachers of Mathematics is of interest to the mathematics education community as well as to other researchers, practitioners and policy makers concerned with the professional education of teachers.

 Grundat på en klassificering av teoretiska perspektiv, aspekter av matematiska problem, kunskapsbildning och undervisning, presenteras en epistemologisk modell för problemslösningens roll i en matematisk praktik.

We study the problem of finding two solutions to a constraint satisfaction problem which differ on the assignment of as many variables as possible – the Max Hamming Distance problem for CSPs – a problem which can, among other things, be seen as a domain independent way of quantifying “ignorance.” The first algorithm we present is an microstructure based algorithm for Max Hamming Distance 2-SAT, improving the previously best known algorithm for this problem, which has a running time of . We also give algorithms based on enumeration techniques for solving both Max Hamming Distance l-SAT, and the general Max Hamming Distance (d,l)-CSP, the first non-trivial algorithms for these problems. The main results here are that if we can solve l-SAT in and (d,l)-CSP in , then the corresponding Max Hamming problems can be solved in and , respectively.

Numerical techniques for data analysis and feature extraction are discussed using the framework of matrix rank reduction. The singular value decomposition (SVD) and its properties are reviewed, and the relation to Latent Semantic Indexing (LSI) and Principal Component Analysis (PCA) is described. Methods that approximate the SVD are reviewed. A few basic methods for linear regression, in particular the Partial Least Squares (PLS) method, are presented, and analyzed as rank reduction methods. Methods for feature extraction, based on centroids and the classical Linear Discriminant Analysis (LDA) , as well as an improved LDA based on the generalized singular value decomposition (LDA/GSVD) are described. The effectiveness of these methods are illustrated using examples from information retrieval, and 2 dimensional representation of clustered data.