x, 164 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / We study the topology of the space of metrics of positive scalar curvature on a compact manifold. The main tool we use for constructing such metrics is the surgery technique of Gromov and Lawson. We extend this technique to construct families of positive scalar curvature cobordisms and concordances which are parametrised by Morse functions and later, by generalised Morse functions. We then use these results to study concordances of positive scalar curvature metrics on simply connected manifolds of dimension at least five. In particular, we describe a subspace of the space of positive scalar curvature concordances, parametrised by generalised Morse functions. We call such concordances Gromov-Lawson concordances. One of the main results is that positive scalar curvature metrics which are Gromov-Lawson concordant are in fact isotopic. This work relies heavily on contemporary Riemannian geometry as well as on differential topology, in particular pseudo-isotopy theory. We make substantial use of the work of Eliashberg and Mishachev on wrinkled maps and of results by Hatcher and Igusa on the space of generalised Morse functions. / Committee in charge: Boris Botvinnik, Chairperson, Mathematics; James Isenberg, Member, Mathematics; Hal Sadofsky, Member, Mathematics; Christopher Phillips, Member, Mathematics; Michael Kellman, Outside Member, Chemistry

In this thesis, we investigate a special class of multi-agent systems, which we call reciprocal multi-agent (RMA) systems. The evolution of agents in a RMA system is governed by interactions between pairs of agents. Each interaction is reciprocal, and the magnitude of attraction/repulsion depends only on distances between agents. We investigate the class of RMA systems from four perspectives, these are two basic properties of the dynamical system, one formula for computing the Morse indices/co-indices of critical formations, and one formation control model as a variation of the class of RMA systems. An important aspect about RMA systems is that there is an equivariant potential function associated with each RMA system so that the equations of motion of agents are actually a gradient flow. The two basic properties about this class of gradient systems we will investigate are about the convergence of the gradient flow, and about the question whether the associated potential function is generically an equivariant Morse function. We develop systematic approaches for studying these two problems, and establish important results. A RMA system often has multiple critical formations and in general, these are hard to locate. So in this thesis, we consider a special class of RMA systems whereby there is a geometric characterization for each critical formation. A formula associated with the characterization is developed for computing the Morse index/co-index of each critical formation. This formula has a potential impact on the design and control of RMA systems. In this thesis, we also consider a formation control model whereby the control of formation is achieved by varying interactions between selected pairs of agents. This model can be interpreted in different ways in terms of patterns of information flow, and we establish results about the controllability of this control system for both centralized and decentralized problems. / Engineering and Applied Sciences

Orientador: Ketty Abaroa de Rezende / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação Científica / Made available in DSpace on 2018-08-24T17:12:31Z (GMT). No. of bitstreams: 1 EspirituLedesma_GuidoGerson_D.pdf: 1229937 bytes, checksum: 00f2d538b5b2a2c4147d828351f4ef16 (MD5) Previous issue date: 2014 / Resumo: Neste trabalho, usamos os grafos de Lyapunov como uma ferramenta combinat{\'o}ria para obter classifica\c{c}{\~o}es completas de fluxos Smale sobre $\ss$ e fluxos Morse-Novikov sobre superf{\'i}cies orient{\'a}veis e n{\~a}o orient{\'a}veis. Esta classifica\c{c}{\~a}o consiste em obter condi\c{c}{\~o}es necess{\'a}rias e suficientes que devem ser satisfeitas por um grafo de Lyapunov abstrato de forma a ser associado a um fluxo Smale sobre $\ss$ ou um fluxo Morse-Novikov sobre uma superf{\'i}cie respectivamente. Assim nesta tese de doutorado obtemos os seguintes resultados: \begin{enumerate} \item As condições locais que devem ser satisfeitas por cada vértice do grafo de Lyapunov, assim como as condições globais que devem ser satisfeitas pelos grafos para estarem associados a um fluxo Smale sobre $\ss$ ou a um fluxo Morse-Novikov sobre uma superfície s{\~a}o determinadas. \item A realização destes grafos abstratos sujeita {\'a}s condições determinadas acima, como fluxos Smale sobre $\ss$ ou fluxos Morse-Novikov sobre superfícies respectivamente, são obtidas. \end{enumerate} / Abstract: In this work Lyapunov graphs are used as a combinatorial tool in order to obtain a complete classification of Smale flows on $\ss$ and Morse-Novikov flows on orientable and non-orientable surfaces. This classification consists in determining necessary and sufficient conditions that must be satisfied by an abstract Lyapunov graph so that it is associated to a Smale flow on $\ss$ or to a Morse-Novikov flow on a surface respectively.\\ In summary in this doctoral thesis we obtain the following results: \begin{enumerate} \item The local conditions that must be satisfied by each vertex on a Lyapunov graph is determinated as well as the global conditions on the graph in order for it to be associated to a Smale flow on $\ss$ or a Morse-Novikov flow on a surface. \item The realization of these graphs subject to the conditions found above as Smale flows on $\ss$ or as Morse-Novikov flows on surfaces respectively is obtained. \end{enumerate} / Doutorado / Matematica / Doutor em Matemática

Orientador: Ketty Abaroa de Rezende / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação Científica / Made available in DSpace on 2018-08-25T10:15:50Z (GMT). No. of bitstreams: 1 Lima_DahisyValadaodeSouza_D.pdf: 22146296 bytes, checksum: c88725de657b032422b9e4614ccd91a9 (MD5) Previous issue date: 2014 / Resumo: O tema principal desta tese é o estudo de fluxos gradientes associados a campos vetoriais $-\nabla f$ em variedades fechadas, onde $f$ é uma função do tipo Morse, Morse circular e Morse-Bott. Para obter informações dinâmicas em cada caso, utilizamos ferramentas algébricas e topológicas, tais como sequências espectrais e matrizes de conexão. No contexto de Morse, consideramos um complexo de cadeias $(C,\Delta)$ gerado pelos pontos críticos de $f$ onde $\Delta$ conta (com sinal) o número de linhas do fluxo entre dois pontos críticos consecutivos. Uma análise via sequências espectrais $(E^{r},d^{r})$ é feita para se obter resultados de continuação global em superfícies. Nós relacionamos as diferenciais da $r$-ésima página de $(E^{r},d^{r})$ com cancelamentos dinâmicos entre pontos críticos. No caso de função de Morse circular $f:M \rightarrow S^{1}$, o método da varredura para um complexo de Novikov $(\mathcal{N},\Delta)$ associado $f$ e gerado pelos pontos críticos de $f$ é definido sobre o anel $\mathbb{Z}((t))$. Este método produz a cada etapa matrizes de Novikov. Provamos que a matriz final produzida pelo método da varredura tem entradas polinomiais, o que é surpreendente, já que as matrizes intermediárias podem ter séries infinitas como entradas. Apresentamos resultados que mostram que os módulos e diferenciais de uma sequência espectral associada a $(\mathcal{N},\Delta)$ podem ser recuperados através do método da varredura. Para fluxos gradientes associados a funções de Morse-Bott, as singularidades formam variedades críticas. Usamos a teoria do índice de Conley para obter uma caracterização do conjunto de matrizes de conexão para fluxos Morse-Bott. Obtemos resultados sobre o efeito no conjunto de matrizes de conexão causado por mudanças na ordem parcial e na decomposição de Morse de um conjunto invariante isolado / Abstract: The main theme in this thesis is the study of gradient flows associated to a vector field $-\nabla f$ on closed manifolds, where $f$ is either a Morse function, a circle-valued Morse function or a Morse-Bott function. In order to obtain dynamical information, we make use of algebraic and topological tools such as spectral sequences and connection matrices. In the Morse context, consider a chain complex $(C,\Delta)$ generated by the critical points of $f$, where $\Delta$ counts the number of flow lines between consecutive critical points with signs. A spectral sequence $(E^{r},d^{r})$ analysis is used to obtain results on global continuation of flows on surfaces. A link is established between the differentials on the $r$-th page of $(E^{r},d^{r})$ and cancellation of critical points. In the circle-valued Morse case $f:M \rightarrow S^{1}$, a sweeping algorithm for the Novikov chain complex $(\mathcal{N},\Delta)$ associated to $f$ and generated by the critical points of $f$ is defined over the ring $\mathbb{Z}((t))$. This algorithm produces at each stage Novikov matrices. We prove that the last Novikov matrix has polynomial entries which is quite surprising since the matrices in the intermediary stages may have infinite series entries. We also present results showing that the modules and differentials of the spectral sequence associated to $(\mathcal{N},\Delta)$ can be retrieved through the sweeping algorithm. For gradient flows associated to Morse-Bott functions, the singularities form critical manifolds. We use the Conley index theory for the critical manifolds in order to characterize the set of connection matrices for Morse-Bott flows. Results are obtained on the effects on the set of connection matrices caused by a change in the partial ordering and Morse decomposition of isolated invariant sets / Doutorado / Matematica / Doutora em Matemática

Ce mémoire présente une nouvelle méthode d’étudier des fonctions de Morse sur une variété compacte. Plus précisément, les croisements entre les lignes de flot de pseudo-gradients associés à des fonctions de Morse permettent de définir géométriquement des morphismes entre les complexes de Morse, morphismes qui ne peuvent généralement pas être obtenus par une homotopie. Cette nouvelle classe de morphismes mène à la définition d’une catégorie triangulée. La question centrale est de savoir si tout objet de cette catégorie est décomposable en cône itéré de fonctions de Morse parfaites. En effet, une telle décomposition simplifierait l’étude de la dynamique d’une fonction de Morse en l’interprétant plutôt comme plusieurs fonctions parfaites. Une seconde question d’importance porte sur une condition de généricité globale à laquelle est soumise cette catégorie triangulée. Nous étudions la possibilité de s’en soustraire en proposant une méthode de déformations des fonctions de Morse. / This master’s thesis introduces a new way to sudy Morse functions on a compact manifold. More specifically, crossings between flows of pseudo-gradients associated to Morse functions allow one to define geometric realisations of morphisms between the Morse complexes. This new class of morphisms leads to the definition of a triangulated category. The main question is to determine if every object of this category admits an iterated cone decomposition. Such a decomposition would greatly simplify the study of the dynamic of a Morse function by interpreting it as many perfect Morse functions. A second topic concerns the global genericity condition to which this category is subject. We study a way, through deformation of Morse functions, to avoid such a constraint.

Cette thèse est consacrée à l’étude de trois questions différentes concernant les groupoïdes de Lie et leurs applications. Le premier chapitre présente quelques préliminaires sur les groupoïdes de Lie. Dans le chapitre 2, on exprime la déformation de Witten à l’aide d’une déformation au cone normal et la théorie de C∗-modules ce qui nous permet de retrouver les inégalités de Morse. Notre méthode se généralise au cas des feuilletages. Dans le chapitre 3, on donne une construction simple du groupoïde de déformation construit par Choi-Pönge et Van Erp-Yuncken. Rappelons que celui-ci décrit le calcule pseudo-différentiel inhomogène grâce au travail de Debord-Skandalis et Van Erp- Yuncken. Notre construction montre que le groupoïde de déformation est en fait une déformation au cone normal classique itérée. Dans le chapitre 4, suivant le travail de Antonini, Azzali et Skandalis, on construit un élément en KK-théorie équivariante qui permet d’exprimer directement les invariants de Chern-Simons en K-théorie. Dans l’appendice on donne quelques rappels sur la KK-théorie équivariante et la KK-théorie réelle introduite par Antonini, Azzali et Skandalis. / This thesis is devoted to the study of three different questions concerning Lie groupoids and their applications. The first chapter presents some preliminaries on Lie groupoids. In Chapter 2, Witten’s deformation is expressed using deformation to the normal cone construction and the theory of C∗-modules, which allows us to reprove the Morse inequalities. Our method is generalised to the case of foliations. In Chapter 3, we give a simple construction of the deformation groupoid built by Choi-Pönge and Van Erp-Yuncken. Recall that this groupoid describes the inhomogeneous pseudo-differential calculus thanks to the work of Debord-Skandalis and Van Erp-Yuncken. Our construction shows that the deformation groupoid is actually an iterated classical deformation to the normal cone. In Chapter 4, following the work of Antonini, Azzali and Skandalis, we construct an element in equivariant KK-theory that allows us to express the Chern-Simons invariants directly in K-theory. In the appendix we give some reminders about the equivariant KK-theory and the real KK-theory introduced by Antonini, Azzali and Skandalis.