Research. Thesis (M.Sc.)--University of Melbourne, Dept. of Computer Science and Software Engineering, 2006. / Typescript. Includes bibliographical references (leaves 163-170).

Thesis (M.C.S.) - Carleton University, 2005. / Includes bibliographical references (p. 127-130). Also available in electronic format on the Internet.

Thesis (M.S.)--University of North Carolina at Wilmington, 2005. / Includes bibliographical references (leaves: 60-61)

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 132-133). Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 132-133). Also available on the Internet.

Orientadores: Marcelo Firer, Luiz Antonio Barrera San Martin / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-05T23:33:46Z (GMT). No. of bitstreams: 1 Talpo_HumbertoLuiz_D.pdf: 1408389 bytes, checksum: b11f884cbf1e05f81138a8e91a5980dc (MD5) Previous issue date: 2006 / Resumo: Seja G uma árvore homogênea e Aut(G) seu grupo de automorfismos. Um automorfismo f Î Aut(G) é par se d(f(x),x) º0 mod 2 para todo vértice x Î G, onde d(.,.) é a função distância definida pelo comprimento do menor caminho ligando os vértices. O conjunto Aut+(G) de todos os automorfismos pares é um subgrupo de índice 2 em Aut(G). Definimos uma geodésica g Ì G como um subgrafo isomorfo a Z (onde Z é visto como um grafo que possui arestas unindo inteiros consecutivos). Uma reflexão em uma geodésica g é um automorfismo involutivo f (f² =1) tal que f(x) = x se, e somente se, x Î G. Denotamos por R o conjunto de todas as reflexões em geodésicas. Neste trabalho (Capítulo 2) provamos que, dada uma árvore homogênea de grau par G, o número de cobertura de Aut+(G) pelas reflexões em geodésicas é 11, no seguinte sentido: dado f Î Aut+(G) existem f1, f2,... fk com k £ 11, tais que f(x) = fk °fk-1°...°f1(x) para todo vértice x em G. Além disso, considerando árvores homogêneas, sabemos que o grupo de automorfismos é completo e o subgrupo de automorfismos pares é simples. Flexibilizamos a condição de homogeneidade e conseguimos demonstrar (Capítulo 3) para o caso de árvores semi-homogêneas, que o grupo de automorfismos é simples e completo / Abstract: Let G be a homogeneous tree and Aut(G) its group of automorphism. An automorphism Î Aut(G) is said to be even if d(f(x),x) º0 mod 2 for every vertex x Î G of , where d(.,.) is the canonical distance function defined by the minimum length of paths connecting the vertices. The set Aut+(G) of all even automorphism is a subgroup of index 2 in Aut(G). We define a geodesic g Ì G as a subtree isomorphic to the standard tree of the integers Z, that is, a homogeneous subtree of degree 2. A reflection in a geodesic g is an involutive automorphism f (f² =1) such that f(x) = x if x Î G. We denote by R the set of all reflections in geodesics. In this work (Chapter 2) we prove that, for every even degree tree G, the covering number of Aut+(G) by reflections in geodesics is 11, in the sense that give f Î Aut+(G) there are f1, f2,... fk with k £ 11, such that f(x) = fk °fk-1°...°f1(x) for every vertex x in G.Moreover, if we consider homogeneous trees we know that automorphisms group is complete and the even automorphisms subgroup is simple. We vary the homogeneous condition and we prove that (Chapter 3) for the semi-homogeneous trees, the automorphisms group is simple and complete / Doutorado / Doutor em Matemática

Orientadores: Roberto de Alencar Lotufo, Letícia Rittner / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-25T05:00:23Z (GMT). No. of bitstreams: 1 Souza_RobertoMedeirosde_M.pdf: 27462483 bytes, checksum: fd6e6b42169addd0201eeda81c058aea (MD5) Previous issue date: 2014 / Resumo: A Árvore de Componentes é uma estrutura de dados que representa uma imagem através da relação de hierarquia de seus componentes conexos. Ela é uma estrutura adequada para a implementação de filtros conexos e que foi utilizada com sucesso em muitas aplicações. A Árvore Máxima é uma estrutura compacta para a representação da Árvore de Componentes. A principal contribuiçãoo deste trabalho é a proposta do filtro de Simplificação Maximal da Árvore Máxima (MMS) com dois possíveis critérios para efetuar o seu cálculo: um critério de limiarização normalizada (MMS-T) e um critério de Regiões Extremais Maximamente Estáveis (MMS-MSER). Uma metodologia para aplicar o filtro MMS em associação com o filtro de Extinção, que é formalmente definido nesse trabalho, é apresentada. É mostrado que após a aplicação da metodologia de simplificação, a qual escolhe o número de máximos relevantes a serem mantidos na imagem, o número de nós da Árvore Máxima simplificada é no máximo duas vezes o número de máximos mantidos. Para definir o filtro MMS, novos conceitos, como nó composto e sub-ramo são apresentados. Esses conceitos são importantes para definir muitos algoritmos da Árvore Máxima, e eles possuem interpretações interessantes em termos de processamento de imagem. Possíveis aplicações da metodologia proposta, tais como localização de texto, simplificação/segmentação de imagens e reconhecimento de objetos são ilustrados para mostrar o potencial da metodologia. Também, estudos explortatórios de detecção de regiões salientes em imagens e análise da robustez da topologia da Árvore Máxima são apresentados / Abstract: The Component Tree is a data structure that represents an image through the hierarchical relationship of its connected components. It is an adequate structure to implement connected filters, and it has been successfully used in many applications. The Max-Tree is a compact structure for the Component Tree representation. The main contribution of this work is the proposal of the Maximal Max-Tree Simplification (MMS) filter with two possible criteria to compute the filter: a normalized threshold criterion (MMS-T) and a Maximally Stable Extremal Regions (MSER) criterion (MMS-MSER). A methodology to apply the MMS filter in association to the Extinction filter, which is formally defined in this work, is presented. It is shown that after applying our simplification methodology, which sets the number of relevant maxima in the image to be kept, the number of nodes in the simplified Max-Tree is at most twice this number. In order to define the MMS filter, new concepts, such as composite node and sub-branches are introduced. These concepts are important to define many Max-Tree algorithms, and they have interesting interpretations in terms of image processing. Possible applications of the methodology proposed, such as text location, object recognition, and image simplification/segmentation are illustrated to demonstrate the potential of this methodology. Also, exploratory studies, such as detection of distinguished regions in the image, and analysis of the robustness of the Max-tree topology are presented / Mestrado / Engenharia de Computação / Mestre em Engenharia Elétrica

The main contribution of this dissertation proposes a new paradigm, called the parentheses matching paradigm. It claims that this paradigm is well suited for designing efficient parallel algorithms for a broad class of nonnumeric problems. To demonstrate its applicability, we present three cost-optimal parallel algorithms for breadth-first traversal of general trees, sorting a special class of integers, and coloring an interval graph with the minimum number of colors.

This study examines the performance of concurrent algorithms for B-trees and linear hashing. B-trees are widely used as an access method for large, single key, database files, stored in lexicographic order on secondary storage devices. Linear hashing is a fast and reliable hash algorithm, suitable for accessing records stored unordered in buckets. This dissertation presents performance results on implementations of concurrent Bunk-tree and linear hashing algorithms, using lock-based, partitioned and distributed methods on the Sequent Symmetry shared memory multiprocessor system and on a network of distributed processors created with PVM (Parallel Virtual Machine) software. Initial experiments, which started with empty data structures, show good results for the partitioned implementations and lock-based linear hashing, but poor ones for lock-based Blink-trees. A subsequent test, which started with loaded data structures, shows similar results, but with much improved performances for locked Blink- trees. The data also highlighted the high cost of split operations, which reached up to 70% of the total insert time.

Image representation plays an important role in image processing applications, which usually. contain a huge amount of data. An image is a two-dimensional array of points, and each point contains information (eg: color). A 1024 by 1024 pixel image occupies 1 mega byte of space in the main memory. In actual circumstances 2 to 3 mega bytes of space are needed to facilitate the various image processing tasks. Large amounts of secondary memory are also required to hold various data sets. In this thesis, two different operations on the quadtree are presented. There are, in general, two types of data compression techniques in image processing. One approach is based on elimination of redundant data from the original picture. Other techniques rely on higher levels of processing such as interpretations, generations, inductions and deduction procedures (1, 2). One of the popular techniques of data representation that has received a considerable amount of attention in recent years is the quadtree data structure. This has led to the development of various techniques for performing conversions and operations on the quadtree. Klinger and Dyer (3) provide a good bibliography of the history of quadtrees. Their paper reports experiments on the degree of compaction of picture representation which may be achieved with tree encoding. Their experiments show that tree encoding can produce memory savings. Pavlidis [15] reports on the approximation of pictures by quadtrees. Horowitz and Pavidis [16] show how to segment a picture using traversal of a quadtree. They segment the picture by polygonal boundaries. Tanimoto [17] discusses distortions which may occur in quadtrees for pictures. Tanimoto [18, p. 27] observes that quadtree representation is particularly convenient for scaling a picture by powers of two. Quadtrees are also useful in graphics and animation applications [19, 20] which are oriented toward construction of images from polygons and superpositiofis of images. Encoded pictures are useful for display, especially if encoding lends itself to processing.