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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Ordered spaces of continuous functions and bitopological spaces

Nailana, Koena Rufus 11 1900 (has links)
This thesis is divided into two parts: Ordered spaces of Continuous Functions and the algebras associated with the topology of pointwise convergence of the associated construct, and Strictly completely regular bitopological spaces. The Motivation for part of the first part (Chapters 2, 3 and 4) comes from the recent study of function spaces for bitopological spaces in [44] and [45]. In these papers we see a clear generalisation of classical results in function spaces ( [14] and [55]) to bi-topological spaces. The well known definitions of the pointwise topology and the compact open topology in function spaces are generalized to bitopological spaces, and then familiar results such as Arens' theorem are generalised. We will use the same approach in chapters 2, 3 and 4 to formulate analogous definitions in the setting of ordered spaces. Well known results, including Arens' theorem, are also generalised to ordered spaces. In these chapters we will also compare function spaces in the category of topological spaces and continuous functions, the category of bi topological spaces and bicontinuous functions, and the category of ordered topological spaces and continuous order-preserving functions. This work has resulted in the publication of [30] and [31]. Continuing our study of Function Spaces, we oonsider in Chapters 5 and 6 some Categorical aspects of the construction, motivated by a series of papers which includes [39], [40], [41] and [50]. In these papers the Eilenberg-Moore Category of algebras of the monad induced by the Hom-functor on the categories of sets and categories of topological spaces are classified. Instead of looking at the whole product topology we will restrict ourselves to the pointwise topology and give examples of the EilenbergMoore Algebras arising from this restriction. We first start by way of motivation, with the discussion of the monad when the range space is the real line with the usual topology. We then restrict our range space to the two point Sierpinski space, with the aim of discovering a topological analogue of the well known characterization of Frames as the Eilenberg-Moore Category of algebras associated with the Hom-F\mctor of maps into the Sierpinski space [11]. In this case the order structure features prominently, resulting in the category Frames with a special property called "balanced" and Frame homomorphisms as the Eilenberg-Moore category of M-algebras. This has resulted in [34]. The Motivation for the second part comes from [20] and [15]. In [20], J. D. Lawson introduced the notion of strict complete regularity in ordered spaces. A detailed study of this notion was done by H-P. A. Kiinzi in [15]. We shall introduce an analogous notion for bitopological spaces, and then shall also compare the two notions in the categories of bi topological spaces and bicontinuous functions, and of ordered topological spaces and continuous order-preserving functions via the natural functors considered in the previous chapters. We further study the Stone-Cech bicompactification and Stone-Cech ordered compactification in the two categories. This has resulted in [32] and [33] / Mathematical Sciences / D. Phil. (Mathematics)
22

A topological approach to nonlinear analysis

Peske, Wendy Ann 01 January 2005 (has links)
A topological approach to nonlinear analysis allows for strikingly beautiful proofs and simplified calculations. This topological approach employs many of the ideas of continuous topology, including convergence, compactness, metrization, complete metric spaces, uniform spaces and function spaces. This thesis illustrates using the topological approach in proving the Cauchy-Peano Existence theorem. The topological proof utilizes the ideas of complete metric spaces, Ascoli-Arzela theorem, topological properties in Euclidean n-space and normed linear spaces, and the extension of Brouwer's fixed point theorem to Schauder's fixed point theorem, and Picard's theorem.
23

Continuidade de atratores para sistemas dinâmicos: decomposição de Morse, equi-atração e domínios ilimitados / Continuity of attractors for dynamical systems: Morse decompositions, equiattraction and unbounded domains

Costa, Henrique Barbosa da 28 July 2016 (has links)
Neste trabalho estudamos a dinâmica assintótica de problemas parabólicos sob vista de diferentes teorias, particularmente interessados na estabilidade das propriedades dinâmicas dos sistemas. Estudamos a equi-atração no caso não autônomo pelos semifluxos skew-product, que transformam o sistema dinâmico não autônomo em um autônomo num espaço de fase conveniente. Para modelos multívocos, em que o semifluxo é uma função cujos valores são conjuntos, desenvolvemos a decomposição de Morse e mostramos sua equivalência com a existência de um funcional de Lyapunov, que é um resultado muito importante na teoria de semigrupos. Também estudamos a continuidade da dinâmica assintótica de um problema parabólico em um domínio ilimitado quando o aproximamos por domínios limitados específicos. / In this work we study assimptotic properties of parabolic problems under some different view of points, particularlly interested in the stability properties of the systems. We study equi-attraction in the non autonomous case using skew-product semiflows, which transform the non autonomous dynamical system into a autonomous one in a convenient phase space. For multivalued semiflows, in which the semiflow is a set valued function, we develop the Morse decomposition and show its equivalence with admiting a Lyapunov funcional, wich is a important result on the semigroup theory. We also study the continuity of the asymptotic dynamic for a parabolic problem in an unbouded domain when we approach it by bounded ones.
24

Aplicações da teoria dos espaços coarse a espaços de Banach e grupos topológicos / Applications of coarse spaces theory to Banach spaces and topological groups

Garcia, Denis de Assis Pinto 24 June 2019 (has links)
Este trabalho é uma contribuição ao estudo da geometria de larga escala de espaços de Banach e de grupos topológicos. Embora esses dois campos sejam tradicionalmente estudados de forma independente, em 2017, Christian Rosendal mostrou que eles podem ser encarados como faces distintas de algo maior: a geometria grosseira de grupos topológicos. Uma ferramenta essencial para o desenvolvimento dessa nova abordagem é a noção de estrutura coarse, introduzida por John Roe em 2003, a qual pode ser vista como a contraparte de larga escala do conceito de estrutura uniforme. Por essa razão, os capítulos iniciais da dissertação destinam-se a apresentar uma introdução elementar à teoria dos espaços uniformes e dos espaços coarse, destacando os conceitos-chave para a compreensão dos demais capítulos e conferindo particular atenção ao estudo de uniformidades e estruturas coarse associadas a grupos topológicos, dentre as quais são enfatizadas as estruturas uniforme à esquerda e coarse à esquerda de um grupo topológico. No capítulo 5, são discutidos resultados recentes de Christian Rosendal acerca da existência de mergulhos uniformes e mergulhos grosseiros entre espaços de Banach. Dois dos mais importantes afirmam que, se existir uma função f uniformemente contínua e não colapsada entre os espaços de Banach (X, ||·||_X) e (E, ||·||_E), então, para todo p em [1, + infty[, existirá um mergulho uniforme de (X, ||·||_X) em (l_p(E), ||·||_p) o qual é, também, um mergulho grosseiro, e que, se f for, também, limitada, existirá um mergulho grosseiro uniformemente contínuo de (X, ||·||_X) em (ExE, ||·||_(ExE)). Já no capítulo 6, estuda-se a classe das estruturas coarse invariantes à esquerda sobre grupos. Inicialmente, mostra-se como uma estrutura coarse invariante à esquerda em um grupo (G, · ) pode ser descrita em função de um certo ideal sobre G, e vice-versa. Em seguida, utiliza-se esse resultado para caracterizar a estrutura coarse à esquerda E_L de um grupo topológico (G, · , T) em termos da coleção dos conjuntos grosseiramente limitados em (G, E_L) e, com isso, provar que a estrutura coarse à esquerda associada ao grupo aditivo de um espaço normado coincide com a estrutura coarse limitada induzida pela norma. / This work is a contribution to the study of large-scale geometry of Banach spaces and topological groups. Although these two fields are traditionally studied independently, in 2017, Christian Rosendal showed they can be regarded as different aspects of a more general theory: the coarse geometry of topological groups. An essential tool for the development of this new approach is the notion of coarse structure, introduced by John Roe in 2003, which can be seen as the large-scale counterpart of the concept of uniform structure. For this reason, the initial chapters of this work intend to present an elementary introduction to both uniform and coarse spaces theory, highlighting the key concepts for the understanding of the other chapters and paying particular attention to the study of uniform and coarse structures associated with topological groups, and, mainly, to the left-uniform and the left-coarse structures of a topological group. In Chapter 5, we discuss Rosendal\'s recent results on the existence of uniform and coarse embeddings between Banach spaces. Two of the most important state that, if there is an uncollapsed uniformly continuous function f between the Banach spaces (X, ||·||_X) and (E, ||·||_E), then, for all p in [1, + infty[, (X, ||·||_X) admits a simultaneously uniform and coarse embedding into (l_p(E), ||·||_p), and that, if, in addition, we assume that f maps into a bounded set, then (X, ||·||_X) also admits a uniformly continuous coarse embedding into (ExE, ||·||_(ExE)). On the other hand, in chapter 6, we focus our attention on the class of left-invariant coarse structures on groups. In the first section, we show how a left-invariant coarse structure on a group (G, · ) can be described in terms of a certain ideal on G, and vice versa. After that, we use this result to characterize the left-coarse structure E_L of a topological group (G, · , T) in terms of the collection of the coarsely bounded sets of (G, E_L) and, with this, we prove that the left-coarse structure associated with the additive group of a normed space is simply the bounded coarse structure induced by its norm.
25

Continuidade de atratores para sistemas dinâmicos: decomposição de Morse, equi-atração e domínios ilimitados / Continuity of attractors for dynamical systems: Morse decompositions, equiattraction and unbounded domains

Henrique Barbosa da Costa 28 July 2016 (has links)
Neste trabalho estudamos a dinâmica assintótica de problemas parabólicos sob vista de diferentes teorias, particularmente interessados na estabilidade das propriedades dinâmicas dos sistemas. Estudamos a equi-atração no caso não autônomo pelos semifluxos skew-product, que transformam o sistema dinâmico não autônomo em um autônomo num espaço de fase conveniente. Para modelos multívocos, em que o semifluxo é uma função cujos valores são conjuntos, desenvolvemos a decomposição de Morse e mostramos sua equivalência com a existência de um funcional de Lyapunov, que é um resultado muito importante na teoria de semigrupos. Também estudamos a continuidade da dinâmica assintótica de um problema parabólico em um domínio ilimitado quando o aproximamos por domínios limitados específicos. / In this work we study assimptotic properties of parabolic problems under some different view of points, particularlly interested in the stability properties of the systems. We study equi-attraction in the non autonomous case using skew-product semiflows, which transform the non autonomous dynamical system into a autonomous one in a convenient phase space. For multivalued semiflows, in which the semiflow is a set valued function, we develop the Morse decomposition and show its equivalence with admiting a Lyapunov funcional, wich is a important result on the semigroup theory. We also study the continuity of the asymptotic dynamic for a parabolic problem in an unbouded domain when we approach it by bounded ones.

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