In this thesis, we set out to provide an enhanced set of techniques for determining the eigenvalues of the Laplacian in polygonal domains. Currently, finite-element methods provide a numerical means by which we can approximate these eigenvalues with ease. However, we would like a more analytic method which may allow us to avoid a basic parameter sweep in finite-element software such as COMSOL to determine what could possibly be an "optimal" distribution of eigenvalues. The hope is that this would allow us to draw conclusions about the acoustic quality of a pentagonally-shaped room. First, we find the eigenvalues using a common finite-element method through COMSOL Multiphysics. We then examine another method which makes use of conformal maps and Schwarz-Christoffel transformations with the prospect that it might provide a more analytic understanding of the calculation of these eigenvalues and possibly allow for variation of certain parameters. This method, as far as we could find, had not yet been developed on the pentagon. We end up carrying this method through nearly all of the steps necessary in finding these eigenvalues. We find that the finite-element method is not only easier to use, but is also more efficient in terms of computing power. / Master of Science

In this thesis we present a formalization of the combinatorial part of the proof of Feit-Higman theorem on generalized polygons. Generalised polygons are abstract geometric structures that generalize ordinary polygons and projective planes. They are closely related to finite groups. The formalization is carried out in Agda, a dependently typed functional programming language and proof assistant based on the intuitionist type theory by Per Martin-Löf.

Este trabalho aborda dois problemas de geometria computacional: união de círculos e união de (vários) polígonos. Para o problema da união de círculos, os principais algoritmos da literatura são revisados e um algoritmo simples, porém ineficiente, é introduzido. Este algoritmo é então adaptado para resolver o problema da união de polígonos, produzindo um algoritmo que é competitivo com o estado da arte e, dependendo da aplicação, utiliza menos armazenamento. / This work deals with two problems from the field of computational geometry: union of circles and union of (many) polygons. For the union of circles problem, the main algorithms in the literature are revised and a simple, albeit inefficient, algorithm is introduced. This algorithm is then adapted to solve the union of polygons problem, resulting in an algorithm that is competitive with the state of the art and, depending on the application, makes use of less storage.

The subject of this thesis is the asymptotic behaviour of generating functions of different combinatorial models of two-dimensional lattice walks and polygons, enumerated with respect to different parameters, such as perimeter, number of steps and area. These models occur in various applications in physics, computer science and biology. In particular, they can be seen as simple models of biological vesicles or polymers. Of particular interest is the singular behaviour of the generating functions around special, so-called multicritical points in their parameter space, which correspond physically to phase transitions. The singular behaviour around the multicritical point is described by a scaling function, alongside a small set of critical exponents. Apart from some non-rigorous heuristics, our asymptotic analysis mainly consists in applying the method of steepest descents to a suitable integral expression for the exact solution for the generating function of a given model. The similar mathematical structure of the exact solutions of the different models allows for a unified treatment. In the saddle point analysis, the multicritical points correspond to points in the parameter space at which several saddle points of the integral kernels coalesce. Generically, two saddle points coalesce, in which case the scaling function is expressible in terms of the Airy function. As we will see, this is the case for Dyck and Schröder paths, directed column-convex polygons and partially directed self-avoiding walks. The result for Dyck paths also allows for the scaling analysis of Bernoulli meanders (also known as ballot paths). We then construct the model of deformed Dyck paths, where three saddle points coalesce in the corresponding integral kernel, thereby leading to an asymptotic expression in terms of a bivariate, generalised Airy integral.

In Voronoi-based nearest neighbor search, the Voronoi cell of every point p in a database can be used to check whether p is the closest to some query point q. We extend the notion of Voronoi cells to support uncertain objects, whose attribute values are inexact. Particularly, we propose the Possible Voronoi cell (or PV-cell). A PV-cell of a multi-dimensional uncertain object o is a region R, such that for any point p ∈ R, o may be the nearest neighbor of p. If the PV-cells of all objects in a database S are known, they can be used to identify objects that have a chance to be the nearest neighbor of q. However, there is no efficient algorithm for computing an exact PV-cell. We hence study how to derive an axis-parallel hyper-rectangle (called the Uncertain Bounding Rectangle, or UBR) that tightly contains a PV-cell. We further develop the PV-index, a structure that stores UBRs, to evaluate probabilistic nearest neighbor queries over uncertain data. An advantage of the PV-index is that upon updates on S, it can be incrementally updated. Extensive experiments on both synthetic and real datasets are carried out to validate the performance of the PV-index. / published_or_final_version / Computer Science / Master / Master of Philosophy

Η παρούσα εργασία μελετά τη διδασκαλία της Γεωμετρίας στα σχολεία και τον τρόπο που παρουσιάζεται στα σχολικά εγχειρίδια του Δημοτικού και του Γυμνασίου σε σχέση με το πρόσφατο παρελθόν. Πιο συγκεκριμένα, αντικείμενο της εργασίας είναι ο τρόπος διδασκαλίας των πολυγώνων και πολυέδρων στις παραπάνω βαθμίδες και η ανάδειξη της σημασίας της συμμετρίας στα σχολικά εγχειρίδια. Μάλιστα, μέσα από την παρουσίαση ενός πειράματος με δύο μαθήτριες του Δημοτικού, σχετικά με τα κανονικά πολύγωνα, προτείνεται η μαιευτική μέθοδος ως κατάλληλος τρόπος διδασκαλίας, ιδιαίτερα μεταξύ λίγων συμμετεχόντων. Η εργασία αυτή χωρίζεται σε τέσσερα κεφάλαια. Το πρώτο κεφάλαιο αναφέρεται στη Γεωμετρία των αρχαίων χρόνων και τον τρόπο που αναδύθηκε, ιδιαίτερα κατά τη γεωμετρική εποχή. Συμπεριλαμβάνεται μία σύντομη αναφορά στα πολύγωνα και στα πολύεδρα με ορισμούς και σχετικά θεωρήματα από την εποχή πριν τον Ευκλείδη έως και σήμερα. Στο δεύτερο κεφάλαιο περιλαμβάνεται η ιστορία της διδασκαλίας της Γεωμετρίας. Αναφέρονται τα αναλυτικά προγράμματα στην Ελλάδα τα οποία αφορούν στη διδασκαλία της Γεωμετρίας στο Δημοτικό και στο Γυμνάσιο, ιδιαίτερα όσο αφορά τους γεωμετρικούς μετασχηματισμούς και τα πολύγωνα, και τα πολύγωνα, και συγκρίνονται με τα αντίστοιχα προγράμματα της Αγγλίας και της Γαλλίας. Στο τρίτο κεφάλαιο παρουσιάζεται η έννοια της συμμετρίας και η ύπαρξή της στη φύση. Στη συνέχεια, περιγράφονται τα θέματα της συμμετρίας που διδάσκονται στις σχολικές τάξεις του Δημοτικού και του Γυμνασίου και τονίζεται η σημασία της εισαγωγής των γεωμετρικών μετασχηματισμών στις μικρές τάξεις. Στο τέταρτο και τελευταίο κεφάλαιο παρουσιάζεται μία έρευνα μικρής κλίμακας στην Ε΄ Δημοτικού που αφορά στους μετασχηματισμούς βασικών σχημάτων, συγκεκριμένα στα στοιχεία συμμετρίας του ισοπλεύρου τριγώνου, του κανονικού εξαγώνου και του κανονικού δεκάγωνου. Ακολουθεί η ανάλυση των απαντήσεων και του ρόλου της «μαιευτικής μεθόδου» που ακολουθήθηκε στην εκπαιδευτική διαδικασία. / This study examines the teaching of geometry in schools and the ways it is presented in textbooks of primary and secondary schools in comparison with the past years. More specifically, the object of study is the method of teaching polygons in the above mentioned classes and the importance of including symmetry in textbooks. Moreover, through the presentation of an experiment with two schoolgirls, about geometric transformations of regular polygons, the Socratic dialogue is proposed, which is relevant especially when it is applied with a few participants. The study is divided into four chapters. The first chapter deals with the origins of geometry in ancient times, mainly through art. It includes a brief reference with definitions and theorems about polygons and polyhedra, dated from Euclid’s era until today. The second chapter includes the history of education of Geometry. The Elementary School and High School curriculum concerning geometry in Greece is compared, in what concerns geometric transformations, with the curricula of England and France. In the third chapter the concept of symmetry and its existence in nature is discussed. Then, the issues of symmetry taught in classrooms of elementary and middle school are outlined, and the importance of the introduction of geometric transformations in small classes is emphasized. In the fourth and final chapter, a small scale experiment is presented, which concerns transformations of regular shapes (equilateral triangle, regular hexagon and regular decagon). The role of the “Socratic Method” in the educational process is discussed in the analysis of the dialogue.

No description available.

Title page, abstract and table of contents only. The complete thesis in print form is available from the University of Adelaide Library. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1274742 / Thesis (Ph.D.) -- University of Adelaide, School of Psychology, 2007

Thesis (M.S.)--State University of New York at Binghamton, Department of Computer Science, 2005. / Includes bibliographical references.

Submitted by Maike Costa (maiksebas@gmail.com) on 2016-03-23T13:16:44Z No. of bitstreams: 1 arquivo total.pdf: 1967447 bytes, checksum: af6baac55076357093ed86cc379bab4b (MD5) / Made available in DSpace on 2016-03-23T13:16:44Z (GMT). No. of bitstreams: 1 arquivo total.pdf: 1967447 bytes, checksum: af6baac55076357093ed86cc379bab4b (MD5) Previous issue date: 2015-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this paper, we study a special class of planar curves, convex curves of constant width. Moreover show basic examples of these curves, starting with the Reuleaux triangle that indeed is what has the smallest area when the constant width is de ned unlike the circle has the largest area and is also constant width. We generalize the construction of the Reuleaux triangle to regular polygons with odd numbers of sides that are called Reuleaux polygons. Finally we propose activities for the polygons of study in primary and secondary education as a suggestion for a school education, by reference to the polygons of Reuleaux in particular the Reuleaux triangle. / Neste trabalho, estudaremos uma classe especial de curvas planas, as curvas convexas de largura constante. Mostraremos ademais os exemplos básicos destas curvas, começando com o Triângulo de Reuleaux que de fato é o que tem a menor área quando a largura constante é de nida ao contrário do círculo que tem a maior área e também é de largura constante. Generalizamos a construção do Triângulo de Reuleaux aos polígonos regulares com um número ímpar de lados que são chamados polígonos de Reuleaux. Por último propomos atividades para o estudo de polígonos no ensino fundamental e médio como sugestão para uma educação escolar, tendo como referência os Polígonos de Reuleaux em particular o Triângulo de Reuleaux.