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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.
31

Real Simple Lie Algebras: Cartan Subalgebras, Cayley Transforms, and Classification

Lewis, Hannah M. 01 December 2017 (has links)
The differential geometry software package in Maple has the necessary tools and commands to automate the classification process for complex simple Lie algebras. The purpose of this thesis is to write the programs to complete the classification for real simple Lie algebras. This classification is difficult because the Cartan subalgebras are not all conjugate as they are in the complex case. For the process of the real classification, one must first identify a maximally noncompact Cartan subalgebra. The process of the Cayley transform is used to find this specific Cartan subalgebra. This Cartan subalgebra is used to find the simple roots for the given real simple Lie algebra. With this information, we can then create a Satake diagram. Then we match our given algebra's Satake diagram to a Satake diagram of a known algebra. The programs explained in this thesis complete this process of classification.
32

Fusion of the Parastrophic Matrix and Weak Cayley Table

Perry, Nathan C. 16 June 2009 (has links) (PDF)
The parastrophic matrix and Weak Cayley Tables are matrices that have close ties to the character table. Work by Ken Johnson has shown that fusion of groups induces a relationship between the character tables of the groups. In this paper we will demonstrate a similar induced relationship between the parastrophic matrices and Weak Cayley Tables of the fused groups.
33

Gibbs Measures for Models on Lines and Trees / Medidas de Gibbs para modelos em retas e árvores

Endo, Eric Ossami 31 July 2018 (has links)
In this thesis we study various properties of the spins models, in particular, Ising and Dyson models. We study the stability of the phase transition of the nearest-neighbor ferromagnetic Ising model when we add a perturbation to the critical external field that becomes weaker far from the root of the Cayley tree. We also study the relation between g-measures and Gibbs measures, showing that the Dyson model at sufficiently low temperature is not a g-measure. Counting contours on trees is also studied, showing the characterization of the trees that have infinite number of contours, and comparisons between various definitions of contours. We also study the measures of the spatial Gibbs random graphs, and their local convergence. / Nesta tese estudamos diversas propriedades dos modelos de spins, em particular, os modelos de Ising e Dyson. Estudamos a estabilidade da transição de fase no modelo de Ising ferromagnético de primeiros vizinhos quando adicionamos uma perturbação no campo externo crítico pela qual se torna mais fraca ao estar distante da raiz da árvore de Cayley. Estudamos a relação entre g-medidas e medidas de Gibbs, mostrando que a medida de Gibbs do modelo de Dyson a temperaturas suficientemente baixas não é uma g-medida. Também estudamos contagem de contornos em árvores, mostramos uma caracterização das árvores que possuem um número infinito de contornos de um tamanho fixo envolvendo um vértice, e comparamos entre diversas definições de contornos. Estudamos também as medidas de grafos aleatórios spatial Gibbs, e suas convergências locais.
34

Graphages à type d'isomorphisme prescrit / Homogeneous Graphings

Mercier, Pierre-Adelin 24 September 2012 (has links)
On considère R une relation d’équivalence borélienne standard de type I I1 sur un espace de probabilités (X, µ). On étudie une certaine propriété d’homogénéité pour un graphage fixé de la relation R : on suppose que les feuilles du graphage sont toutes isomorphes à un certain graphe transitif (connexe, infini, localement fini) Γ. Que peut-on dire sur la relation ? Dans ce cas, en considérant une action "à la Mackey", on montre qu’il existe (Z ,η) un revêtement standard probabilisé de (X, µ), une action libre (qui préserve η) sur Z du groupe G (localement compact, à base dénombrable d’ouverts) des automorphismes du graphe et un isomorphisme stable des groupoïdes mesurés associés. On fait le lien entre les propriétés du groupe G et celles de la relation de départ ; en particulier la propriété (T), (H) et la moyennabilité "passent" du graphe à la relation et réciproquement. On déduit aussi de la construction quelques couplages d’équivalence mesurée (ou plus généralement des "randembeddings") entre certains sous-groupes des automorphismes de Γ et tout groupe qui contient orbitalement la relation R. Dans un deuxième chapitre, on aborde le cas particulier de la propriété (T) relative pour les paires de groupes (ΓxZ^2, Z^2), où Γ est un sous-groupe non moyennable de SL(2,Z). Cette propriété a d’abord été prouvée par Marc Burger, puis "re-démontrée" plus "visuellement" quelques années plus tard dans le cas de SL(2,Z)xZ^2 par Y. Shalom, en utilisant des découpages du plan. On reprend cette technique dans le cas général du théorème de Burger afin d’obtenir par un algorithme des constantes de Kazhdan explicites pour toute paire (ΓxZ^2, Z^2). / We consider a measure preserving standard borel equivalence relation R on a standard probability space (X,µ). We study a particular property of homogeneity for a fixed graphing of the relation R : We assume that the leaves of the graphing are all isomorphic to a given transitive graph Γ (connected, infinite, locally finite). What can be known about the relation ?In this case, considering a « Mackey action », we show that there exists a standard covering of (X,µ) i.e. a standard space Z; a probability measure η; a free, measure-preserving action on Z of G the (locally compact, second countable) group of all graph automorphisms of Γ and a stable isomorphism of the associated measured groupoid with R. We investigate some links between properties of G (resp. of the graph Γ) and those of R. In particular, Kazhdan property (T), Haagerup property (H) and amenability are preserved from the graph to the relation and conversely. We also deduce from the construction some couplings of measured equivalence (more generally some randembeddings) between subgroups of G and any group orbitally containing R. In a second chapter, we deal with the relative property (T) for the pairs (ΓxZ^2,Z^2), where Γ is a non-amenable subgroup of SL(2,Z). This property was first proved by M. Burger. Later on, Y. Shalom gave a more geometrical proof in the case of SL(2,Z)xZ^2, by using partitions of the plane. Following the same techniques in the general case of Burger's theorem, we develop an algorithm producing explicit constants for all pairs (ΓxZ^2,Z^2).
35

Graphes, Partitions et Classes : G-graphs et leurs applications / Graphs, Partitions and Cosets : G-graphs and Their Applications

Tanasescu, Mihaela-Cerasela 05 November 2014 (has links)
Les graphes définis à partir de structures algébriques possèdent d’excellentes propriétés de symétries particulièrement intéressantes. L’exemple le plus flagrant est la notion de graphe de Cayley qui s’est révélée très riche non seulement du point de vue théorique mais aussi pratique par ses applications à de nombreux domaines incluant l’architecture des réseaux ou les machines parallèles. Néanmoins, la régularité des graphes de Cayley se révèle parfois être une limite étant donné qu’ils sont toujours sommet-transitifs et donc en particulier non pertinents pour générer des réseaux semiréguliers.Cette observation a motivé, en 2005, la définition d’une nouvelle classe de graphes définis à partir d’un groupe, appelés G-graphes. Ils possèdent aussi de nombreuses propriétés de régularité mais de manière moins restrictive.Cette thèse propose un nouveau regard sur cette classe de graphes par une approche plutôt orientée recherche opérationnelle alors que la grande majorité des études précédentes est dominée par des approches essentiellement algébriques. Nous-nous sommes alors intéressés à plusieurs questions :— La caractérisation des G-graphes : nous proposons des améliorations par rapport aux précédents résultats.— Identifier des classes de graphes comme des G-graphes grâce à des isomorphismes ou en utilisant le théorème de caractérisation.— Etudier la structure et les propriétés de ces graphes, en particulier pour de possibles applications aux réseaux : colorations semi-régulières, symétries et robustesse.— Une approche algorithmique pour la reconnaissance de cette classe avec notamment un premier exemple de cas polynomial lorsque le groupe est abélien. / Interactions between graph theory and group theory have already led to interesting results for both domains. Graphs defined from algebraic groups have highly symmetrical structure giving birth to interesting properties. The most famous example is Cayley graphs, which revealed to be particularly interesting both from a theoretical and a practical point of view due to their applications in several domains including network architecture or parallel machines. Nevertheless, the regularity of Cayley graphs is also a limit as they are always vertex-transitive and therefore not relevant to generate semi-regular networks. This observation motivated the definition, in 2005, of a new family of graphs defined from a group, called G-graphs. They also have many regular properties but are less restrictive. These graphs are in particular semi-regular k-partite, with a chromatic number k directly given in the group representation and they can be either transitive or not.This thesis proposes a new insight into this class of graphs using an approach based on operational research while most of previous studies have been so far dominated by algebraic approaches. Then, the thesis addresses different kind of questions:— Characterizing G-graphs: we propose improvements of previous results.— Identifying some classes of graphs as G-graphs through isomorphism or using the characterization theorem.— Studying the structure and properties of these graphs, in particular for possible applications to networks: semi-regular coloring, symmetries and robustness.— Algorithmic approach for recognizing this class with a first example of polynomial case when the group is abelian.
36

Estudo da função de correlação do modelo de Potts na rede de Bethe. / Study of pair correlation function of the Potts model in the Bethe lattice.

Martinez, Alexandre Souto 21 November 1988 (has links)
Neste trabalho consideramos o modelo de Potts na árvore de Cayley submetida a um campo magnético. Esse campo pode ser representado pela interação dos spins da árvore com um spin adicional, denominado spin fantasma. Essa nova rede passa a ser chamada de árvore de Cayley fechada e assimétrica. Sendo uma rede hierárquica, ela representa soluções exatas que são obtidas quando as técnicas do grupo de renormalização no espaço real são aplicadas. Subtraindo os efeitos de superfície e considerando somente o interior da árvore (rede de Bethe), esses resultados reproduzem os resultados da aproximação de campo médio de Bethe-Peierls. Com a finalidade de estudar a função de correlação do modelo de Potts na rede de Bethe, consideramos primeiramente uma cadeia de Potts interagindo com um spin fantasma. Através das regras de composição em série e paralelo e do método da quebra e colapso para as trasmissividades térmicas (função de correlação) obtemos uma fórmula de recorrência para a função de correlação entre quaisquer dois spins na cadeia. Mostramos então que pela invariança translacional da rede de Bethe qualquer par de spins pode ser mapeado no sistema anterior. A seguir consideramos o modelo de Potts de um estado na árvore de Cayley fechada e assimétrica. Decimando os spins interiores da unidade geradora da rede, obtemos um mapa polinomial quadrático para a transformação do grupo de renormalização (mapa de Bethe-Peierls). O diagrama de fase desse sistema é então obtido do conjunto de Mandelbrot através de uma transformação de Mobius. O mapa de Bethe-Peierls apresenta dois pontos fixos, que são relacionados com as fases ferro e paramagnética e o regime caótico é identificado com a fase vidro de spin. Esse sistema revela ser o exemplo mais simples de vidro de spin de McKay-Berker-Kirkpatrick. Na rede de Bethe e a campo nulo esse sistema apresenta transições de fase de segunda ordem. Analisando o comportamento crítico da função de correlação e de suas derivadas, vemos que se identificarmos a função de correlação entre o spin fantasma e qualquer spin da rede com a magnetização (por spin) e a função de correlação entre dois spins primeiros vizinhos com a energia interna do sistema, cinco expoentes críticos ((&#948, &#946, &#947 &#8217, &#945, &#945 &#8217) são calculados e satisfazem as relações de escala. Para ilustrar o procedimento recursivo apresentado para calcular a função de correlação entre dois spins separados por ligações m na rede de Bethe, consideramos os spins de Potts de um estado. Obtemos então de forma explícita as correlações para m=1, 2 e 3.0 / In this work we consider the Potts model on the Cayley tree subjected to a magnetic Field. This field can be represented by the interaction of the tree spins with an additional one, denominated ghost spin. This new lattice is then called closed-asymmetric Cayley tree. Being a hierarchical lattice it comes to have exact solutions which are obtained when the real-space renormalization group techniques are applied. Subtracting the surface effects and considering only the tree interior (Bethe lattice), these results reproduce the results of Bethe-Peierls mean-field approximation. With the objective of studying the pair-correlation function of the Potts model on the Bethe lattice, we at first consider a Potts chain interacting with a ghost spin. Throughout the series-parallel composition rules and the break-collapse method for the thermal transmissivities (pair-correlation function) we obtain a recursive relation for the correlation function between any two spins on the chain. We then show, due to the translational invariance of the Bethe lattice, that any pair of spins can be mapped into the latter system. Next we consider the one-state Potts model on the closed asymmetric tree. Decimating the inner spins of the generating unit for the lattice, we obtain a quadratic polynomial map for the renormalization group transformation (Bethe-Peierls map). The phase diagram of this system is obtained from the Mandelbrot set throughout a Mobius transformation. The Bethe-Peierls map has two stable fixed points which are related to the ferro and paramagnetic phases and the chaotic regime is identified with the spin-glass phase. This system turns out to be the simplest example of a McKay-Berker-Kirkpatrick spin glass. On the Bethe lattice with vanishing field this system presents second-order phase transitions. Analyzing the critical behavior of the pair-correlation function and of this derivatives, we see that if we identify the correlation function between the ghost spin and any spin on the lattice with the magnetization (per spin), and the correlation function between two nearest-neighbor spins with the internal energy of the system, five critical exponents (&#948, &#946, &#947 &#8217, &#945, &#945 &#8217) are calculated and they satisfy the scaling relations. In order to illustrate the recursive procedure presented to calculate the pair-correlation function between spins m bonds apart on the Bethe lattice, we consider the one-state Potts spins. We obtain explicitly the correlation for m=1, 2 and 3.
37

Códigos y grafos sobre anillos de enteros complejos

Martínez Fernández, María del Carmen 26 March 2007 (has links)
El objetivo de esta tesis es definir códigos perfectos sobre diferentes espacios de señal multidimensionales. Para resolver este problema, esta memoria presenta una relación original entre las Teorías de Grafos, Números y Códigos. Uno de nuestros principales resultados es la propuesta de una métrica adecuada sobre constelaciones de señal de tipo cuadrático, hexagonal y cuatro-dimensional. Esta métrica es la distancia entre los vértices de una nueva clase de grafos de Cayley definidos sobre diferentes anillos de enteros, en concreto, los enteros de Gauss, Eisenstein-Jacobi y Lipschitz. Así, resolvemos el problema de Teoría de Grafos conocido como el cálculo del conjunto perfecto dominante sobre las familias de grafos definidas en esta memoria. Para cada caso, daremos una condición suficiente para obtener dicho conjunto. La obtención de estos conjuntos de dominación implica directamente la construcción de códigos perfectos sobre los alfabetos que se consideran.Además, se obtendrán algunos resultados de isomorfía y embebimiento de grafos. En particular, se establecerán las relaciones entre grafos circulantes, toroidales y los que se presentan en este trabajo. Más concretamente, se mostrará que siempre existen órdenes para los cuales un grafo Toro puede ser embebido en un grafo Gaussiano, de Esenstein-Jacobi o de Lipschitz. Esto implica que la conocida distancia de Lee es un caso particular de las métricas presentadas en este trabajo. / The aim of this work is to define perfect codes for different multidimensional signal spaces. To solve this problem, this thesis presents an original relationship among the fields of Graph Theory, Number Theory and Coding Theory. One of our main findings is the proposal of a suitable metric over quadratic, hexagonal and four-dimensional constellations of signal points. This metric is the distance among vertices of a new class of Cayley graphs defined over integer rings, namely Gaussian integers, the Eisenstein-Jacobi integers and the Lipschitz integers.A problem in Graph Theory known as the perfect dominating set calculation is solved over the families of graphs defined in this memory. A sufficient condition for obtaining such a set is given for each case. The obtention of these sets of domination directly yields to the construction of perfect codes for the alphabets under consideration. In addition, some isomorphism and graph embedding results are going to be obtained. Specially, the relations between circulant, toroidal and the graphs presented in this work are stated. In particular, there always exist orders for which a Torus graph can be embedded in Gaussian, Eisenstein-Jacobi and Lipschitz graphs. This implies that the well-known Lee distance is a subcase of the metrics presented in this research.
38

Estudo da função de correlação do modelo de Potts na rede de Bethe. / Study of pair correlation function of the Potts model in the Bethe lattice.

Alexandre Souto Martinez 21 November 1988 (has links)
Neste trabalho consideramos o modelo de Potts na árvore de Cayley submetida a um campo magnético. Esse campo pode ser representado pela interação dos spins da árvore com um spin adicional, denominado spin fantasma. Essa nova rede passa a ser chamada de árvore de Cayley fechada e assimétrica. Sendo uma rede hierárquica, ela representa soluções exatas que são obtidas quando as técnicas do grupo de renormalização no espaço real são aplicadas. Subtraindo os efeitos de superfície e considerando somente o interior da árvore (rede de Bethe), esses resultados reproduzem os resultados da aproximação de campo médio de Bethe-Peierls. Com a finalidade de estudar a função de correlação do modelo de Potts na rede de Bethe, consideramos primeiramente uma cadeia de Potts interagindo com um spin fantasma. Através das regras de composição em série e paralelo e do método da quebra e colapso para as trasmissividades térmicas (função de correlação) obtemos uma fórmula de recorrência para a função de correlação entre quaisquer dois spins na cadeia. Mostramos então que pela invariança translacional da rede de Bethe qualquer par de spins pode ser mapeado no sistema anterior. A seguir consideramos o modelo de Potts de um estado na árvore de Cayley fechada e assimétrica. Decimando os spins interiores da unidade geradora da rede, obtemos um mapa polinomial quadrático para a transformação do grupo de renormalização (mapa de Bethe-Peierls). O diagrama de fase desse sistema é então obtido do conjunto de Mandelbrot através de uma transformação de Mobius. O mapa de Bethe-Peierls apresenta dois pontos fixos, que são relacionados com as fases ferro e paramagnética e o regime caótico é identificado com a fase vidro de spin. Esse sistema revela ser o exemplo mais simples de vidro de spin de McKay-Berker-Kirkpatrick. Na rede de Bethe e a campo nulo esse sistema apresenta transições de fase de segunda ordem. Analisando o comportamento crítico da função de correlação e de suas derivadas, vemos que se identificarmos a função de correlação entre o spin fantasma e qualquer spin da rede com a magnetização (por spin) e a função de correlação entre dois spins primeiros vizinhos com a energia interna do sistema, cinco expoentes críticos ((&#948, &#946, &#947 &#8217, &#945, &#945 &#8217) são calculados e satisfazem as relações de escala. Para ilustrar o procedimento recursivo apresentado para calcular a função de correlação entre dois spins separados por ligações m na rede de Bethe, consideramos os spins de Potts de um estado. Obtemos então de forma explícita as correlações para m=1, 2 e 3.0 / In this work we consider the Potts model on the Cayley tree subjected to a magnetic Field. This field can be represented by the interaction of the tree spins with an additional one, denominated ghost spin. This new lattice is then called closed-asymmetric Cayley tree. Being a hierarchical lattice it comes to have exact solutions which are obtained when the real-space renormalization group techniques are applied. Subtracting the surface effects and considering only the tree interior (Bethe lattice), these results reproduce the results of Bethe-Peierls mean-field approximation. With the objective of studying the pair-correlation function of the Potts model on the Bethe lattice, we at first consider a Potts chain interacting with a ghost spin. Throughout the series-parallel composition rules and the break-collapse method for the thermal transmissivities (pair-correlation function) we obtain a recursive relation for the correlation function between any two spins on the chain. We then show, due to the translational invariance of the Bethe lattice, that any pair of spins can be mapped into the latter system. Next we consider the one-state Potts model on the closed asymmetric tree. Decimating the inner spins of the generating unit for the lattice, we obtain a quadratic polynomial map for the renormalization group transformation (Bethe-Peierls map). The phase diagram of this system is obtained from the Mandelbrot set throughout a Mobius transformation. The Bethe-Peierls map has two stable fixed points which are related to the ferro and paramagnetic phases and the chaotic regime is identified with the spin-glass phase. This system turns out to be the simplest example of a McKay-Berker-Kirkpatrick spin glass. On the Bethe lattice with vanishing field this system presents second-order phase transitions. Analyzing the critical behavior of the pair-correlation function and of this derivatives, we see that if we identify the correlation function between the ghost spin and any spin on the lattice with the magnetization (per spin), and the correlation function between two nearest-neighbor spins with the internal energy of the system, five critical exponents (&#948, &#946, &#947 &#8217, &#945, &#945 &#8217) are calculated and they satisfy the scaling relations. In order to illustrate the recursive procedure presented to calculate the pair-correlation function between spins m bonds apart on the Bethe lattice, we consider the one-state Potts spins. We obtain explicitly the correlation for m=1, 2 and 3.
39

A álgebra dos complexos/quatérnios/octônios e a construção de Cayley-Dickson / A álgebra dos complexos/quatérnios/octônios e a construção de Cayley-Dickson

Santos, Davi José dos 30 August 2016 (has links)
Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2016-12-15T15:01:25Z No. of bitstreams: 2 Dissertação - Davi José dos Santos - 2016.pdf: 5567090 bytes, checksum: 5606aa47f640cc5cd4495d2694f38cda (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2016-12-15T17:28:21Z (GMT) No. of bitstreams: 2 Dissertação - Davi José dos Santos - 2016.pdf: 5567090 bytes, checksum: 5606aa47f640cc5cd4495d2694f38cda (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-12-15T17:28:21Z (GMT). No. of bitstreams: 2 Dissertação - Davi José dos Santos - 2016.pdf: 5567090 bytes, checksum: 5606aa47f640cc5cd4495d2694f38cda (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-08-30 / This research with theoretical approach seeks to investigate inmathematics, octonions,which is a non-associative extension of the quaternions. Its algebra division 8-dimensional formed on the real numbers is more extensive than can be obtained by constructing Cayley-Dickson. In this perspective we have as main goal to answer the following question: "What number systems allow arithmetic operations addition, subtraction, multiplication and division? " In the genesis of octonions is the Irish mathematician William Rowan Hamilton, motivated by a deep belief that quaternions could revolutionize mathematics and physics, was the pioneer of a new theory that transformed the modern world. Today, it is confirmed that the complexs/quaternions/octonions and its applications are manifested in different branches of science such as mechanics, geometry, mathematical physics, with great relevance in 3D animation and robotics. In order to investigate the importance of this issue and make a small contribution, we make an introduction to the theme from the numbers complex and present the rationale and motivations of Hamilton in the discovery of quaternions/octonions. Wemake a presentation of the algebraic structure and its fundamental properties. Then discoremos about constructing Cayley-Dickson algebras that produces a sequence over the field of real numbers, each with twice the previous size. Algebras produced by this process are known as Cayley-Dickson algebras; since they are an extension of complex numbers, that is, hypercomplex numbers. All these concepts have norm, algebra and conjugate. The general idea is that the multiplication of an element and its conjugate should be the square of its norm. The surprise is that, in addition to larger, the following algebra loses some specific algebraic property. Finally, we describe and analyze certain symmetry groups with multiple representations through matrixes and applications to show that This content has a value in the evolution of technology. / Esta pesquisa com abordagem teórica busca investigar na matemática, os octônios, que é uma extensão não-associativa dos quatérnios. Sua álgebra com divisão formada de 8 dimensões sobre os números reais é a mais extensa que pode ser obtida através da construção de Cayley-Dickson. Nessa perspectiva temos comometa principal responder a seguinte questão: "Que sistemas numéricos permitemas operações aritméticas de adição, subtração, multiplicação e divisão?" Na gênese dos octônios está o matemático irlandêsWilliam Rowan Hamilton que, motivado por uma profunda convicção de que os quatérnios poderiam revolucionar a Matemática e a Física, foi o pioneiro de uma nova teoria que transformou o mundo moderno. Hoje, confirma-se que os complexos/quatérnios/octônios e suas aplicações se manifestam em diferentes ramos da ciências tais como a mecânica, a geometria, a física matemática, com grande relevância na animação 3D e na robótica. Com o propósito de investigar a importância deste tema e dar uma pequena contribuição, fazemos uma introdução ao tema desde os números complexos e apresentamos o raciocínio e motivações de Hamilton na descoberta dos quatérnios/octônios. Fazemos uma apresentação da estrutura algébrica, bem como as suas propriedades fundamentais. Emseguida discoremos sobre a construção de Cayley-Dickson que produz uma sequência de álgebras sobre o campo de números reais, cada uma com o dobro do tamanho anterior. Álgebras produzidas por este processo são conhecidas como álgebras Cayley-Dickson; uma vez que elas são uma extensão dos números complexos, isto é, os números hipercomplexos. Todos esses conceitos têm norma, álgebra e conjugado. A idéia geral é que o produto de um elemento e seu conjugado deve ser o quadrado de sua norma. A surpresa é que, além de maior dimensão, a álgebra seguinte perde alguma propriedade álgebrica específica. Por fim, descrevemos e analisamos alguns grupos de simetria, com várias representações através de matrizes e aplicações que demonstram que este conteúdo tem uma utilidade na evolução da tecnologia.
40

Cycles in graphs and arc colorings in digraphs / Cycles des graphes et colorations d’arcs des digraphes

He, Weihua 28 November 2014 (has links)
Dans cette thèse nous étudions quatre problèmes de théorie des graphes. En particulier,Nous étudions le problème du cycle hamiltonien dans les line graphes, et aussi nous prouvons l’existence de cycles hamiltoniens dans certains sous graphes couvrants d’un line graphe. Notre résultat principal est: Si L(G) est hamiltonien, alors SL(G) est hamiltonien. Grâce à ce résultat nous proposons une conjecture équivalente à des conjectures célèbres. Et nous obtenons deux résultats sur les cycles hamiltoniens disjoints dans les line graphes.Nous considérons alors la bipancyclicité résistante aux pannes des graphes de Cayley engendrés par transposition d’arbres. Nous prouvons que de tels graphes de Cayley excepté le “star graph” ont une bipancyclicité (n − 3)-arête résistante aux pannes.Ensuite nous introduisons la coloration des arcs d’un digraphe sommet distinguant. Nous étudions la relation entre cette notion et la coloration d’arêtes sommet distinguant dans les graphes non orientés. Nous obtenons quelques résultats sur le nombre arc chromatique des graphes orientés (semi-)sommet-distinguant et proposons une conjecture sur ce paramètre. Pour vérifier cette conjecture nous étudions la coloration des arcs d’un digraphe sommet distinguant des graphes orientés réguliers.Finalement nous introduisons la coloration acyclique des arcs d’un graphe orienté. Nous calculons le nombre chromatique acyclique des arcs de quelques familles de graphes orientés et proposons une conjecture sur ce paramètre. Nous considérons les graphes orientés de grande maille et utilisons le Lemme Local de Lovász; d’autre part nous considérons les graphes orientés réguliers aléatoires. Nous prouvons que ces deux classes de graphes vérifient la conjecture. / In this thesis, we study four problems in graph theory, the Hamiltonian cycle problem in line graphs, the edge-fault-tolerant bipancyclicity of Cayley graphs generated by transposition trees, the vertex-distinguishing arc colorings in digraph- s and the acyclic arc coloring in digraphs. The first two problems are the classic problem on the cycles in graphs. And the other two arc coloring problems are related to the modern graph theory, in which we use some probabilistic methods. In particular,We first study the Hamiltonian cycle problem in line graphs and find the Hamiltonian cycles in some spanning subgraphs of line graphs SL(G). We prove that: if L(G) is Hamiltonian, then SL(G) is Hamiltonian. Due to this, we propose a conjecture, which is equivalent to some well-known conjectures. And we get two results about the edge-disjoint Hamiltonian cycles in line graphs.Then, we consider the edge-fault-tolerant bipancyclicity of Cayley graphs generated by transposition trees. And we prove that the Cayley graph generated by transposition tree is (n − 3)-edge-fault-tolerant bipancyclic if it is not a star graph.Later, we introduce the vertex-distinguishing arc coloring in digraphs. We study the relationship between the vertex-distinguishing edge coloring in undirected graphs and the vertex-distinguishing arc coloring in digraphs. And we get some results on the (semi-) vertex-distinguishing arc chromatic number for digraphs and also propose a conjecture about it. To verify the conjecture we study the vertex-distinguishing arc coloring for regular digraphs.Finally, we introduce the acyclic arc coloring in digraphs. We calculate the acyclic arc chromatic number for some digraph families and propose a conjecture on the acyclic arc chromatic number. Then we consider the digraphs with high girth by using the Lovász Local Lemma and we also consider the random regular digraphs. And the results of the digraphs with high girth and the random regular digraphs verify the conjecture.

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