Master of Science / Department of Electrical and Computer Engineering / Caterina M. Scoglio / Recently, virtualization was proposed in many scientific fields. Virtualization is widely applied in telecommunications where networks are required to be extremely flexible to meet the current and the unpredictable future requirements. The creation of a virtual network over the physical network allows the application developers to design new services provided to the users without modifying the underlay resources. The creation of a virtual network of light paths and light trees over the optical network allows the resources managers to utilize the huge optical capacity more efficiently. In this thesis, we consider the optimal topology design for the virtual networks taking into consideration traffic demands and quality of service constraints of the applications. Considered examples of virtual networks are the overlay networks at the application layer and the virtual light path and light tree networks at the optical layer. In the design of overlay topologies, the performance of the virtual networks is affected by traffic characteristic, and behavior of nodes which can be selfish or cooperative. Both the static and dynamic traffic demand scenarios are considered. The static demand scenario follows well known probability distributions, while in the dynamic traffic scenario, the traffic matrix is predicted through measurements over each link in the network. We study the problem of finding the overlay topology that minimizes a cost function which takes into account the overlay link creation cost and the routing cost. We formulate the problem as an Integer Linear Programming and propose heuristics to find near-optimal overlay topologies with a reduced complexity. Virtual optical networks are designed to support many applications. Multicast sessions are an example of the applications running over the optical network. The main objective in creating the hybrid topology, composed by light paths and light trees, is to increase number of supported multicast sessions through sharing the network resources. The problem of establishing the hybrid topology is formulated using the Integer Linear Programming. Extensive data results and analysis are performed on the generated hybrid topologies for evaluation.

Orientador: Prof. Dr. Jesús Pascual Mena-Chalco / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência da Computação, 2015. / A busca pela origem de indivíduos apresenta-se como uma tentativa recorrente em obter respostas que expliquem o presente, com base no passado e permitam traçar os caminhos do futuro. A origem de um indivíduo esta ligada à algum tipo de relacionamento que possibilite identicar outro que o precedeu. Este modelo de estruturação de grupos sociais é objeto de estudo da genealogia. A genealogia acadêmica utiliza os relacionamentos de orientação entre professores (orientadores) e alunos (orientados) para criar a estrutura social que, comumente, é representada por um grafo de genealogia. O grafo descreve seus vértices como orientadores e orientados e suas arestas direcionadas descrevem as orientações acadêmicas existentes entre eles. Nesta dissertação de mestrado busca-se caracterizar os vértices de um grafo de genealogia considerando somente seus relacionamentos de orientação acadêmica. A caracterização dos vértices é realizada por meio do desenvolvimento e/ou adaptação de um conjunto de métricas topológicas. O conjunto é composto por 22 métricas, sendo 13 de composição descendente ((i) largura, (ii) número de folhas, (iii) profundidade, (iv) fecundidade, (v) fecundidade ponderada, (vi) maior largura, (vii) índice h genealógico, (viii) impacto, (ix) distância média, (x) média dos menores caminhos, (xi) pagerank inverso, (xii) pagerank inverso ponderado e (xiii) balanceamento pela fecundidade), 8 de composição ascendente ((xiv) fecundidade inversa, (xv) fecundidade média do território inverso, (xvi) fecundidade ponderada média do território inverso, (xvii) número de origens, (xviii) largura inversa, (xix) profundidade inversa, (xx) pagerank e (xxi) pagerank ponderado) e 1 de composição mista ((xxii) balanceamento global ). Acreditamos que todas as métricas propostas possam servir de insumo para analisar computacionalmente qualquer grafo de genealogia. Em particular, as métricas propostas foram calculadas para o conjunto de doutores em matemática cadastrados na plataforma do Mathematics Genealogy Project (MGP), que em Abril de 2014 contava com mais de 178 mil registros de 185 países, e permitiu realizar análises para: (i) observar características especícas dos vértices do grafo, (ii) estudar o efeito da abrangência das métricas (janela) na caracterização dos vértices e (iii) classicar os vértices em função dos conjuntos de valores de suas métricas. / The search for the origin of individuals is presented as a recurrent attempt to get answers to explain the present, based on the past and to retrace the paths of the future. The origin of a subject is linked to some kind of relationship that allows identify others that preceded it. The academic genealogy uses the orientation relationships between professors (advisors) and students (advisees) to create a social structure that, commonly, is represented by a genealogy graph. The graph describes its vertices as advisors/advisees and the directed edges describe their existing academic guidelines between them. In this master thesis we present a characterization of a genealogy graph considering only their academic guindance relationships. The characterization of the vertices is performed through the development and / or adaptation of a set of topological metrics. The set consists of 22 metrics. The first 13 descending composition metrics are related with: (i) width, (ii) leaf number, (iii) depth, (iv) fecundity, (v) weighted fecundity, (vi) max width, (vii) genealogical h-index, (viii) impact, (ix) average distance (x) average of the shortest paths, (xi) reverse pagerank, (xii) reverse pagerank weighted and (xiii) balanced fecundity. Eight ascending composition metrics related with: (xiv) reverse fecundity, (xv) fecundity of the reverse territory, (xvi) weighted average fecundity of the reverse territory, (xvii) number of origins, (xviii) reverse width, (xix) reverse depth, (xx) pagerank and (xxi) weighted pagerank. Finally, one mixed composition metrics called (xxii) overall balance. We believe that all proposed metrics can serve as input to analyze genealogy graphs. The proposed metrics were calculated for all PhDs in mathematics registered on Mathematics Genealogy Project (MGP), which in April 2014 had more than 178,000 records from 185 countries, and allowed to perform analysis in order: (i) to observe specic characteristics of the graph vertices, (ii) to study the eect of coverage metrics (i.e, window size) in the characterization of vertices and, (iii) to classify the vertices according to the sets of values of their metrics.