The Lie algebra Vec(ℝ) of polynomial vector fields on the line acts naturally on ℂ[]. This action has a one-parameter family of deformations called the tensor density modules F_λ. The bounded indecomposable modules of Vec(ℝ) of length 2 composed of tensor density modules have been classified by Feigin and Fuchs. We present progress towards describing the annihilators of the unique indecomposable extension of F_λ by F_(λ+2) in the non-resonant case λ ≠ -½. We give the intersection of the annihilator and the subalgebra of lowest weight vectors of the universal enveloping algebra (Vec(ℝ)) of Vec(ℝ). This result is found by applying structural descriptions of the lowest weight vectors of (Vec(ℝ)).

Although both female and male mass murderers have been studied, less attention has been paid to women who commit mass murder. Current literature suggests mass murders committed by women, regardless of offender choice, are well planned, predisposing factors and precipitating events prior to the offence have been noted. This study explored the patterns among the crimes of female family annihilators. This study focuses on an exploratory sample of North American cases, occurring between 1970 and 2010, where females were identified as killing four or more family members during what has been described as a single homicidal event. Using a North American database of newspaper accounts, patterns are uncovered by comparing variables including, but not limited to: motive, number of victims, method of murder, age of offender and victim age. The findings suggest that a clearer profile and set of definitions need to be adopted in discussions of female family annihilators. Practical and theoretical implications will be discussed. / UOIT

No description available.

The superline has one even and one odd coordinate. We consider the Lie superalgebra of contact vector fields on the superline. Its tensor density modules are a one-parameter family of deformations of the natural action on the ring of polynomials on the superline. They are parameterized by a complex number, and they are irreducible when this parameter is not zero. In this dissertation, we describe the annihilating ideals of these representations in the universal enveloping algebra of this Lie superalgebra by providing their generators. We also describe the intersection of all such ideals: the annihilator of the direct sum of the tensor density modules. The annihilating ideal of an irreducible non-zero left module is called a primitive ideal, and the space of all such ideals in the universal enveloping algebra is its primitive spectrum. The primitive spectrum is endowed with the Jacobson topology, which induces a topology on the annihilators of the tensor density modules. We conclude our discussion with a description of the annihilators as a topological space.

No description available.

La recherche d’annulateurs du groupe des classes d’idéaux d’une extension abélienne de Q est un sujet classique et remonte à des travaux de Kummer et Stickelberger. La conjecture de Brumer-Stark porte sur les extensions abéliennes de corps de nombres et prédit qu’un élément de l’anneau de groupe du groupe de Galois, appelé élément de Brumer-Stickelberger, est un annulateur du groupe des classes de l’extension. De plus, elle stipule que les générateurs des idéaux principaux obtenus possèdent des propriétés bien particulières. Cette thèse est dédiée à la généralisation de cette conjecture aux extensions de corps de nombres galoisiennes mais non abéliennes. Dans un premier temps, nous nous focalisons sur l’étude de l’analogue non abélien de l’élément de Brumer, nécessaire à l’établissement d’une conjecture non abélienne. La seconde partie est consacrée à l’énoncé de la conjecture de Brumer-Stark non abélienne et à ses reformulations, ainsi qu’aux propriétés qu’elle vérifie. Nous nous intéressons notamment aux propriétés de changement d’extension. Nous étudions ensuite le cas spécifique des extensions dont le groupe de Galois possède un sous-groupe abélien H distingué d’indice premier. Sous la validité de la conjecture de Brumer-Stark associée à certaines extensions abéliennes, nous en déduisons deux résultats suivant la parité du cardinal de H : dans le cas impair, nous démontrons la conjecture de Brumer-Stark non abélienne, et dans le cas pair, nous établissons un résultat d’abélianité permettant d’obtenir, sous des hypothèses supplémentaires, la conjecture non abélienne. Enfin nous effectuons des vérifications numériques de la conjecture non abélienne permettant de démontrer cette conjecture dans les exemples testés. / Finding annihilators of the ideal class group of an abelian extension of Q is a classical subject which goes back to work of Kummer and Stickelberger. The Brumer-Stark conjecture deals with abelian extensions of number fields and predicts that a group ring element, called the Brumer-Stickelberger element, annihilates the ideal class group of the extension under consideration. Moreover it specifies that the generators thus obtained have special properties. The aim of this work is to generalize this conjecture to non-abelian Galois extensions. We first focus on the study of a non-abelian analogue of the Brumer element, necessary to establish a non-abelian generalization of the conjecture. The second part is devoted to the statement of our non-abelian conjecture, and the properties it satisfies. We are particularly interested in extension change properties. We then study the specific case of extensions whose Galois group has an abelian normal subgroup H of prime index. If the Brumer-Stark conjecture associated to certain abelian subextensions holds, we prove two results according to the parity of the cardinal of H : in the odd case, we get the non-abelian Brumer-Stark conjecture, and in the even case, we establish an abelianity result implying under additional hypotheses the proof of the non-abelian conjecture. Thanks to PARI-GP, we finally do some numerical verifications of the nonabelian conjecture, proving its validity in the tested examples.

Ce mémoire de thèse traite de la stabilité en temps fini et de la stabilisation en temps fini des systèmes dynamiques. En effet, il est souvent important de garantir que pendant le régime transitoire, les trajectoires d'état ne dépassent pas certaines limites prédéfinies afin d'éviter les saturations et l'excitation des non-linéarités du système. Un système dynamique est dit stable en temps fini FTS si, pour tout état initial appartenant à un ensemble borné prédéterminé, la trajectoire d'état reste comprise dans un autre ensemble borné prédéterminé pendant un temps fini et fixé. Lorsque le système est perturbé, on parle de bornitude en temps fini FTB. Premièrement, des nouvelles conditions suffisantes assurant la synthèse d'un correcteur FTB par retour de sortie dynamique des systèmes linéaires continus invariants perturbés ont été développées via une approche descripteur originale. Le résultat a été établi par une transformation de congruence particulière. Les conditions obtenues sont sous forme de LMIs. Deuxièmement, l'utilisation de la notion d'annulateur combinée avec le lemme de Finsler, permet d’obtenir des nouvelles conditions sous formes LMIs garantissant la stabilité et la stabilisation en temps fini des systèmes non linéaires quadratiques. Enfin, pour obtenir des conditions encore moins pessimistes dans un contexte de stabilité en temps fini, de nouveaux développements ont été proposés en utilisant des fonctions de Lyapunov polynomiales / This dissertation deals with the finite time stability and the finite time stabilization of dynamic systems. Indeed, it is often important to ensure that during the transient regime, the state trajectories do not exceed certain predefined limits in order to avoid saturations and excitations of the nonlinearities of the system. Hence the interest is to study the stability of the dynamic system in finite time. A dynamic system is said to be stable in finite time (FTS) if, for any initial state belonging to a predetermined bounded set, the state trajectory remains within another predetermined bounded set for a finite and fixed time. When the system is disturbed, it is called finite time boundedness (FTB). In this manuscript, the goal is to improve the results of finite time stability used in the literature. First, new sufficient conditions expressed in terms of LMIs for the synthesis of an FTB controller by dynamic output feedback have been developed via an original descriptor approach. An original method has been proposed which consists in using a particular congruence transformation. Second, new LMI conditions for the study of finite time stability and finite time stabilization have been proposed for disturbed and undisturbed nonlinear quadratic systems. Third, to obtain even less conservative conditions, new developments have been proposed using polynomial Lyapunov functions