No description available.

James W. Alexander, no artigo[1],mostra que se tivermos um mergulho PL f : \'S POT. 1\' × \'S POT. 1\' \'S POT. 3\', então o fecho de uma das componentes conexas de \'S POT. 3\' f(\'S POT. 1\' × \'S POT. 1\') é homeomorfo a um toro sólido, isto é, homeomorfo a \'S POT. 1\' × \'D POT. 2\'. Este teorema ficou conhecido por Teorema do toro de Alexander. Nesta dissertação, estamos detalhando a demonstração deste teorema feita em[25] que é diferente da demonstração apresentada em [1]. Mais geralmente, para um mergulho diferenciável f : \'S POT. p\' × \'S POT. q\' \'S POT. p + q+1\' , demonstra-se que o fecho de uma das componentes conexasde \'S POT. p +q + 1\' f(\'S POT. p\' × \'S POT. q\') é difeomorfo a \'S POT. p\' × \'D POT. q + 1\' se p q 1 e p + q \'DIFERENTE DE\' 3 ou se p = 2 e q = 1 um dos fechos será homeomorfo a \'S POT. 2\' × \'D POT. 2\' , nesta dissertação estaremos também detalhando estas demonstrações feita em [20] / James W. Alexander shows in[1] that the closure of one of the two connected components of \'S POT. 3\'f( \'S POT. 1 × \'S POT. 1\') is homeomorphic to a solid torus \'S POT. 1\' × \'D POT. 2\' , where f : \'S POT. 1\' ×\' SPOT. 1\' \'S POT. 3\' is a PL embedding. This result became known as Alexanders torus theorem. In this dissertation we are detailing the proof of this theorem made in[25] which is different from the demonstration presented in[1]. More generally, when considering a smooth embeding f : \'S POT. p\' × \'S POT. q\' \' SPOT. p+q+1\' , it is demonstrated that the closure of one of the two connected components \'S POT. p+q+1\' f (\'S POT. p\' × \'S POT. q\' ) is diffeomorphic to \'S POT. p\' × \'D POT. q+1\' if p q 1 and p+q \'DIFFERENT OF\' 3 or if p = 2 and q = 1 one of the closures will be homeomorphic to \'S POT. 2\' × \'D POT. 2\'. In this work we are also detailing the proves made in[20]

James W. Alexander, no artigo[1],mostra que se tivermos um mergulho PL f : \'S POT. 1\' × \'S POT. 1\' \'S POT. 3\', então o fecho de uma das componentes conexas de \'S POT. 3\' f(\'S POT. 1\' × \'S POT. 1\') é homeomorfo a um toro sólido, isto é, homeomorfo a \'S POT. 1\' × \'D POT. 2\'. Este teorema ficou conhecido por Teorema do toro de Alexander. Nesta dissertação, estamos detalhando a demonstração deste teorema feita em[25] que é diferente da demonstração apresentada em [1]. Mais geralmente, para um mergulho diferenciável f : \'S POT. p\' × \'S POT. q\' \'S POT. p + q+1\' , demonstra-se que o fecho de uma das componentes conexasde \'S POT. p +q + 1\' f(\'S POT. p\' × \'S POT. q\') é difeomorfo a \'S POT. p\' × \'D POT. q + 1\' se p q 1 e p + q \'DIFERENTE DE\' 3 ou se p = 2 e q = 1 um dos fechos será homeomorfo a \'S POT. 2\' × \'D POT. 2\' , nesta dissertação estaremos também detalhando estas demonstrações feita em [20] / James W. Alexander shows in[1] that the closure of one of the two connected components of \'S POT. 3\'f( \'S POT. 1 × \'S POT. 1\') is homeomorphic to a solid torus \'S POT. 1\' × \'D POT. 2\' , where f : \'S POT. 1\' ×\' SPOT. 1\' \'S POT. 3\' is a PL embedding. This result became known as Alexanders torus theorem. In this dissertation we are detailing the proof of this theorem made in[25] which is different from the demonstration presented in[1]. More generally, when considering a smooth embeding f : \'S POT. p\' × \'S POT. q\' \' SPOT. p+q+1\' , it is demonstrated that the closure of one of the two connected components \'S POT. p+q+1\' f (\'S POT. p\' × \'S POT. q\' ) is diffeomorphic to \'S POT. p\' × \'D POT. q+1\' if p q 1 and p+q \'DIFFERENT OF\' 3 or if p = 2 and q = 1 one of the closures will be homeomorphic to \'S POT. 2\' × \'D POT. 2\'. In this work we are also detailing the proves made in[20]

No description available.

Submitted by Etelvina Domingos (etelvina.domingos@ufpe.br) on 2015-03-10T17:09:30Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) HLAG.pdf: 1126552 bytes, checksum: 1e1ac46e79a77b1688e9cb1f88285609 (MD5) / Made available in DSpace on 2015-03-10T17:09:30Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) HLAG.pdf: 1126552 bytes, checksum: 1e1ac46e79a77b1688e9cb1f88285609 (MD5) Previous issue date: 2012-01 / O objetivo desse trabalho é mostrar que os Top Intersection Numbers das Grassmannianas de retas G(2,n+2) satisfazem a relação de recorrência apresentada no artigo "Catalan Traffic at the Beach" e a conexão desses dois com os números de Catalan. Tudo isso será feito com a teoria das Derivações de Schubert e sua conexão com as Grassmannianas de retas.

We study Cheeger-Simons differential characters in order to define higher form U(1) gauge fields and their Wilson lines. We then go on to define generalized global symmetries. This is a topological formulation of symmetries which has interesting consequences when the charged operators extend through space. Our main source of such charged operators are the generalized Wilson lines. A higher form Noether theorem and a Ward identity are given for transformations of Wilson lines. As examples of quantum field theories with generalized symmetries we cover Sigma models, Maxwell theory and BF-theory. These are examples of Z, U(1) and Zn symmetries respectively. Finally we discuss spontaneous symmetry breaking for higher dimensional symmetries and a Goldstone theorem is provided. These massless Goldstone bosons are shown to have internal structure corresponding to non-zero spin. The photon is identified as the spin one Goldstone boson in QED. Our review of generalized symmetries is more formal than the ones in other papers. This makes various points explicit and leads to general selection rules. Many results of previous papers are reproduced in detail.

Cette thèse réunit en trois articles mon intérêt éclectique pour la théorie des graphes. Le premier problème étudié est la conjecture de Erdos-Faber-Lovász: La réunion de k graphes complets distincts, ayant chacun k sommets, qui ont deux-à-deux au plus un sommet en commun peut être proprement coloriée en k couleurs. Cette conjecture se caractérise par le peu de résultats publiés. Nous prouvons qu’une nouvelle classe de graphes, construite de manière inductive, satisfait la conjecture. Le résultat consistera à présenter une classe qui ne présente pas les limitations courantes d’uniformité ou de régularité. Le deuxième problème considère une conjecture concernant la couverture des arêtes d’un graphe: Si G est un graphe simple avec alpha(G) = 2, alors le nombre minimum de cliques nécessaires pour couvrir l’ensemble des arêtes de G (noté ecc(G)) est au plus n, le nombre de sommets de G. La meilleure borne connue satisfaite par ecc(G) pour tous les graphes avec nombre d’indépendance de deux est le minimum de n + delta(G) et 2n − omega(racine (n log n)), où delta(G) est le plus petit nombre de voisins d’un sommet de G. Notre objectif a été d’obtenir la borne ecc(G) <= 3/2 n pour une classe de graphes la plus large possible. Un autre résultat associé à ce problème apporte la preuve de la conjecture pour une classe particulière de graphes: Soit G un graphe simple avec alpha(G) = 2. Si G a une arête dominante uv telle que G \ {u,v} est de diamètre 3, alors ecc(G) <= n. Le troisième problème étudie le jeu de policier et voleur sur un graphe. Presque toutes les études concernent les graphes statiques, et nous souhaitons explorer ce jeu sur les graphes dynamiques, dont les ensembles d’arêtes changent au cours du temps. Nowakowski et Winkler caractérisent les graphes statiques pour lesquels un unique policier peut toujours attraper le voleur, appellés cop-win, à l’aide d’une relation <= définie sur les sommets de ce graphe: Un graphe G est cop-win si et seulement si la relation <= définie sur ses sommets est triviale. Nous adaptons ce théorème aux graphes dynamiques. Notre démarche nous mène à une relation nous permettant de présenter une caractérisation des graphes dynamiques cop-win. Nous donnons ensuite des résultats plus spécifiques aux graphes périodiques. Nous indiquons aussi comment généraliser nos résultats pour k policiers et l voleurs en réduisant ce cas à celui d’un policier unique et un voleur unique. Un algorithme pour décider si, sur un graphe périodique donné, k policiers peuvent capturer l voleurs découle de notre caractérisation. / This thesis represents in three articles my eclectic interest for graph theory. The first problem is the conjecture of Erdos-Faber-Lovász: If k complete graphs, each having k vertices, have the property that every pair of distinct complete graphs have at most one vertex in common, then the vertices of the resulting graph can be properly coloured by using k colours. This conjecture is notable in that only a handful of classes of EFL graphs are proved to satisfy the conjecture. We prove that the Erdos-Faber-Lovász Conjecture holds for a new class of graphs, and we do so by an inductive argument. Furthermore, graphs in this class have no restrictions on the number of complete graphs to which a vertex belongs or on the number of vertices of a certain type that a complete graph must contain. The second problem addresses a conjecture concerning the covering of the edges of a graph: The minimal number of cliques necessary to cover all the edges of a simple graph G is denoted by ecc(G). If alpha(G) = 2, then ecc(G) <= n. The best known bound satisfied by ecc(G) for all the graphs with independence number two is the minimum of n + delta(G) and 2n − omega(square root (n log n)), where delta(G) is the smallest number of neighbours of a vertex in G. In this type of graph, all the vertices at distance two from a given vertex form a clique. Our approach is to extend all of these n cliques in order to cover the maximum possible number of edges. Unfortunately, there are graphs for which it’s impossible to cover all the edges with this method. However, we are able to use this approach to prove a bound of ecc(G) <= 3/2n for some newly studied infinite families of graphs. The third problem addresses the game of Cops and Robbers on a graph. Almost all the articles concern static graphs, and we would like to explore this game on dynamic graphs, the edge sets of which change as a function of time. Nowakowski and Winkler characterize static graphs for which a cop can always catch the robber, called cop-win graphs, by means of a relation <= defined on the vertices of such graphs: A graph G is cop-win if and only if the relation <= defined on its vertices is trivial. We adapt this theorem to dynamic graphs. Our approach leads to a relation, that allows us to present a characterization of cop-win dynamic graphs. We will then give more specific results for periodic graphs, and we will also indicate how to generalize our results to k cops and l robbers by reducing this case to one with a single cop and a single robber. An algorithm to decide whether on a given periodic graph k cops can catch l robbers follows from our characterization.