Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 345-346).

Les mathématiques tropicales sont une branche des mathématiques correspondant à l'étude d'une algèbre modifiée grâce à la redéfinition de l'addition et de la multiplication. Les mathématiques tropicales sont généralement définies grâce au minimum et à l'addition (algèbre min-plus) mais le terme est parfois utilisé pour désigner l'algèbre max-plus, définie grâce au maximum et à l'addition. Briec et Horvath ont introduit une notion de convexité très proche qui apparait comme un cas limite d’opérateurs utilisés en théorie de l’optimisation par Avriel (1972) et de Ben-Tal (1977). En suivant cette ligne d’investigation, nous allons proposer, dans le domaine de l’économie de la production et de l’optimisation de portefeuille, une certaine classe de modèles économiques à élaborés à partir de ces notions. Pour ce faire, nous introduisons une nouvelle classe de technologie de production permettant de prendre en compte les structures d’homothe´tie-translation dans la mesure de productivité au travers du concept de la Convexité Max-Plus. Ensuite, nous allons établir une relation topologique entre plusieurs classes de modèles convexes généralisés connus. Nous analysons pour cela la limite de Painlevé-Kuratowski des modèles CES-CET et des technologies non paramétriques satisfaisant une hypothèse de rendements d’échelle alpha. On montre que leurs limites topologiques convergent vers les modèles de production B-convexe et Cobb-Douglas. Enfin, nous allons montrer que l'amélioration de l'efficacité technique d’une coalition d’entreprises s'avère compatible avec les technologies de semi-treillis dans un jeu coopératif. Nous introduisons ensuite, le concept d’écart absolu moyen dans la sélection du portefeuille en utilisant le « Shortage Function » qui prend en compte simultanément la réduction des inputs et l’augmentation des outputs comme dans la théorie de la production. Enfin, nous allons étendre le concept de B-convexité et de l’inverse B-convexité en se concentrant sur le calcul des mesures d’efficacité technique dans le graphe. / Tropical algebra is the tropical analogue of linear algebra by redefining the usual operation addition by the maximization operation and the usual addition operation as multiplication. Briec and Horvath introduced a concept of convexity very close to this concept quoted above which appears as one of the limits of use of the theory of optimization by Avriel (1972) and Ben-Tal (1977). Following this line of investigation, we give an overview of contributions involving a semilattice structure of production technologies and an optimization portfolio. To do that, firstly, we propose a framework allowing to consider both semilattice structure and translation homothetic properties in productivity measurement. We introduce the concept of Max-Plus convexity which combine both an upper semilattice structure and an additivity assumption. We establish a topological relation between several classes of known generalized convex models using some basic algebraic convex structures. We analyze the Painlevé-Kuratowski limit of the CES-CET and Alpha-returns to scale models. It is shown that their topological limits yield the B-convex and Cobb-Douglas production models. Moreover, we show that the improvement of technical efficiency is compatible with semilattice technologies in a cooperative game. Then, we introduce a criterion to measure portfolio efficiency based upon the minimization of the maximum absolute deviation and minimum absolute deviation from the expected return using the Shortage function. Finally, we derive simple closed-form expressions to calculate the hyperbolic measure in the case of inverse and B-Convexity that evaluates technical efficiency in the full input-output space.

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Thesis (MSc (Mathemathical Sciences))--Stellenbosch University, 2009. / We have the familiar Kuratowski-Mr owka theorem in topology, where compactness is characterised by a closure and a projection-map (X is compact i p : X Y ! Y is a closed mapping, for any space Y , i.e. p(A) = p(A) A X Y ). Using this as our starting point, we generalise compactness to a categorical setting. We then generalise even further to "asymmetric" compactness. Then we discuss a functional approach to compactness, where we do not explicitly mention closure operators. All this provides economical proofs as well as applications in di erent areas of mathematics.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The present dissertation aims to introduce the basic concepts of graph theory to explore the concept of planarity and present a beautiful theorem connected to this theme. Graph theory is a very effective tool for solving problems involving several areas of knowledge. Some of these problems are related to planarity of graphs. Thus, this work presents Kuratowski’s theorem, with the beauty of its demonstration, which provides a necessary and sufficient condition for a graph to be planar, observing if it contains a specific type of subgraph related to complete and split graphs. / A presente dissertaçãoo tem como objetivo introduzir os conceitos básicos da teoria dos grafos para explorar o conceito de planaridade e apresentar um belo teorema ligado a esse tema. A teoria dos grafos é uma ferramenta muito eficaz na resolução de problemas que envolvem diversas áreas de conhecimento. Alguns destes problemas estão relacionados `a planaridade de grafos. Dessa forma, este trabalho apresenta o teorema de Kuratowski, com a beleza de sua demonstra¸c˜ao, que fornece uma condição necessária e suficiente para um grafo ser planar, observando se o mesmo contém um tipo específico de subgrafo relacionado a grafos completos e bipartidos. / São Cristóvão, SE

O principal objetivo deste trabalho é estudar a existência de soluções para alguns problemas de valores de contorno de equações diferenciais ordinárias não lineares em dimensão finita e infinita. Todos os sistemas considerados nesta investigação são transformados em equações funcionais nas quais o objetivo é encontrar um ponto fixo de um oportuno operador definido em um espaço de funções (que depende do problema estudado). Para isso, faremos uso do grau de Leray-Schauder e de um conceito de grau topológico, devido a R. Nussbaum, para perturbações não compactas da identidade em espaços de Banach. / The main purpose of this work is to study the existence of solutions to some boundary value problems for nonlinear ordinary differential equations in finite and infinite dimension. All systems considered in this research are transformed into functional equations in which the objective is to find a fixed point of a suitable operator defined in a space of functions (which depends on the studied problem). To do this, we use the Leray-Schauder degree and a concept of topological degree due to R. Nussbaum for non-compact perturbations of identity in Banach spaces.

O principal objetivo deste trabalho é estudar a existência de soluções para alguns problemas de valores de contorno de equações diferenciais ordinárias não lineares em dimensão finita e infinita. Todos os sistemas considerados nesta investigação são transformados em equações funcionais nas quais o objetivo é encontrar um ponto fixo de um oportuno operador definido em um espaço de funções (que depende do problema estudado). Para isso, faremos uso do grau de Leray-Schauder e de um conceito de grau topológico, devido a R. Nussbaum, para perturbações não compactas da identidade em espaços de Banach. / The main purpose of this work is to study the existence of solutions to some boundary value problems for nonlinear ordinary differential equations in finite and infinite dimension. All systems considered in this research are transformed into functional equations in which the objective is to find a fixed point of a suitable operator defined in a space of functions (which depends on the studied problem). To do this, we use the Leray-Schauder degree and a concept of topological degree due to R. Nussbaum for non-compact perturbations of identity in Banach spaces.