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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.
91

Módulos tipo Verma sobre álgebra TKK afim estendida / Verma type module over an extended affine TKK algebra.

Anliy Natsuyo Nashimoto Sargeant 30 March 2007 (has links)
As álgebras TKK afins estendidas pertencem à classe de álgebras de Lie chamada álgebras de Lie afins estendidas do tipo $A_1$. Elas são obtidas a partir de um semi-reticulado do $\\mathbbR^n$. Estudamos a estrutura dos módulos tipo Verma sobre a álgebra TKK afim estendida para um semi-reticulado (não-reticulado) do $\\mathbbR^2$. Quando fixamos um conjunto positivo de raízes isotrópicas chamado standard encontramos quatro órbitas da subálgebra de Borel que dão origem a distintos módulos tipo Verma sobre a álgebra TKK afim estendida. Estudamos as estruturas de seus submódulos e encontramos critérios de irredutibilidade para os módulos de Verma clássico e imaginário. / The extended affine TKK Lie algebras belong to a class of Lie algebras called extended affine Lie algebras of type $A_1$. They are obtained from a semilattice on $\\mathbbR^n$. We studied the structure of the Verma type modules for the extended affine TKK algebra obtained from a semi-lattice (non-lattice) on $\\mathbbR^2$. Fixing a set of positive isotropic roots called standard we found four orbits of the Borel subalgebra each of which give distinct Verma modules for the extended affine TKK algebra. We studied the structures of their submodules and found a criteria for irreducibility for the classic and imaginary Verma modules.
92

Propriedade de Specht e crescimento das identidades polinomiais graduadas de sl_2 / Specht property and growth of the graded polynomial identities of sl_2

Souza, Manuela da Silva, 1985- 22 August 2018 (has links)
Orientador: Plamen Emilov Kochloukov / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Científica / Made available in DSpace on 2018-08-22T00:36:15Z (GMT). No. of bitstreams: 1 Souza_ManueladaSilva_D.pdf: 983599 bytes, checksum: c9cf8976bde9d56083976fba17e385d9 (MD5) Previous issue date: 2013 / Resumo: O resumo poderá ser visualizado no texto completo da tese digital / Abstract: The abstract is available with the full electronic document / Doutorado / Matematica / Doutora em Matemática
93

Algèbres de Hopf d'arbres et structures pré-Lie / Hopf algebras of trees and pre-Lie structures

Saïdi, Abdellatif 17 December 2011 (has links)
Nous étudions dans cette thèse l’algèbre de Hopf H associée à l’opérade pré-Lie. L’espace des éléments primitifs du dual gradué est muni d’une structure pré-Lie à gauche notée ⊲ définie par l’insertion d’un arbre dans un autre. Nous retrouvons la relation de dérivation entre le produit pré-Lie ⊲ et le produit pré-Lie de greffe → sur les éléments primitifs du dual gradué de l’algèbre de Hopf de Connes Kreimer HCK. Nous mettons en évidence un coproduit sur le produit tensoriel H ⊗HCK, qui en fait une algèbre de Hopf dont le dual gradué est isomorphe à l’algèbre enveloppante du produit semi-direct des deux algèbres de Lie considérées. Nous montrons que l’espace engendré par les arbres enracinés qui ont au moins une arête, muni du produit d’insertion, est une algèbre pré-Lie (non libre) engendrée par deux éléments. Nous mettons en évidence deux familles de relations. De plus nous montrons un résultat similaire pour l’algèbre pré-Lie associée à l’opérade NAP. Finalement on introduit les opérades à débit constant et on montre que l’opérade pré-Lie s’obtient comme déformation de l’opérade NAP dans ce cadre. / We investigate in this thesis the Hopf algebra structure on the vector space H spanned by the rooted forests, associated with the pre-Lie operad. The space of primitive elements of the graded dual of this Hopf algebra is endowed with a left pre-Lie product denoted by ⊲, defined in terms of insertion of a tree inside another. In this thesis we retrieve the “derivation” relation between the pre-Lie structure ⊲ and the left pre-Lie product → on the space of primitive elements of the graded dual H0CK of the Connes-Kreimer Hopf algebra HCK, defined by grafting. We also exhibit a coproduct on the tensor product H⊗HCK, making it a Hopf algebra the graded dual of which is isomorphic to the enveloping algebra of the semidirect product of the two (pre-)Lie algebras considered. We prove that the span of the rooted trees with at least one edge endowed with the pre-Lie product ⊲ is generated by two elements. It is not free : we exhibit two families of relations. Moreover we prove a similar result for the pre-Lie algebra associated with the NAP operad. Finally, we introduce current preserving operads and prove that the pre-Lie operad can be obtained as a deformation of the NAP operad in this framework.
94

Geometrické řízení hadům podobných robotů / Geometrically controlled snake-like robot model

Shehadeh, Mhd Ali January 2020 (has links)
This master’s thesis describes equations of motion for dynamic model of nonholonomic constrained system, namely the trident robotic snakes. The model is studied in the form of Lagrange's equations and D’Alembert’s principle is applied. Actually this thesis is a continuation of the study going at VUT about the simulations of non-holonomic mechanisms, specifically robotic snakes. The kinematics model was well-examined in the work of of Byrtus, Roman and Vechetová, Jana. So here we provide equations of motion and address the motion planning problem regarding dynamics of the trident snake equipped with active joints through basic examples and propose a feedback linearization algorithm.
95

Arithmetic and hyperbolic structures in string theory / Structures arithmétiques et hyperboliques en théorie des cordes

Persson, Daniel 12 June 2009 (has links)
Résumé anglais: <p><p>This thesis consists of an introductory text followed by two separate parts which may be read independently of each other. In Part I we analyze certain hyperbolic structures arising when studying gravity in the vicinity of spacelike singularities (the BKL-limit). In this limit, spatial points decouple and the dynamics exhibits ultralocal behaviour which may be mapped to an auxiliary problem given in terms of a (possibly chaotic) hyperbolic billiard. In all supergravities arising as low-energy limits of string theory or M-theory, the billiard dynamics takes place within the fundamental Weyl chambers of certain hyperbolic Kac-Moody algebras, suggesting that these algebras generate hidden infinite-dimensional symmetries of gravity. We investigate the modification of the billiard dynamics when the original gravitational theory is formulated on a compact spatial manifold of arbitrary topology, revealing fascinating mathematical structures known as galleries. We further use the conjectured hyperbolic symmetry E10 to generate and classify certain cosmological (S-brane) solutions in eleven-dimensional supergravity. Finally, we show in detail that eleven-dimensional supergravity and massive type IIA supergravity are dynamically unified within the framework of a geodesic sigma model for a particle moving on the infinite-dimensional coset space E10/K(E10). <p><p>Part II of the thesis is devoted to a study of how (U-)dualities in string theory provide powerful constraints on perturbative and non-perturbative quantum corrections. These dualities are typically given by certain arithmetic groups G(Z) which are conjectured to be preserved in the effective action. The exact couplings are given by moduli-dependent functions which are manifestly invariant under G(Z), known as automorphic forms. We discuss in detail various methods of constructing automorphic forms, with particular emphasis on a special class of functions known as (non-holomorphic) Eisenstein series. We provide detailed examples for the physically relevant cases of SL(2,Z) and SL(3,Z), for which we construct their respective Eisenstein series and compute their (non-abelian) Fourier expansions. We also discuss the possibility that certain generalized Eisenstein series, which are covariant under the maximal compact subgroup K(G), could play a role in determining the exact effective action for toroidally compactified higher derivative corrections. Finally, we propose that in the case of rigid Calabi-Yau compactifications in type IIA string theory, the exact universal hypermultiplet moduli space exhibits a quantum duality group given by the emph{Picard modular group} SU(2,1;Z[i]). To verify this proposal we construct an SU(2,1;Z[i])-invariant Eisenstein series, and we present preliminary results for its Fourier expansion which reveals the expected contributions from D2-brane and NS5-brane instantons. <p><p>/<p><p>Résumé francais: <p><p>Cette thèse est composée d'une introduction suivie de deux parties qui peuvent être lues indépendemment. Dans la première partie, nous analysons des structures hyperboliques apparaissant dans l'étude de la gravité au voisinage d'une singularité de type espace (la limite BKL). Dans cette limite, les points spatiaux se découplent et la dynamique suit un comportement ultralocal qui peut être reformulé en termes d'un billiard hyperbolique (qui peut être chaotique). Dans toutes les supergravités qui sont des limites de basse énergie de théories de cordes ou de la théorie M, la dynamique du billiard prend place à l'intérieur des chambres de Weyl fondamentales de certaines algèbres de Kac-Moody hyperboliques, ce qui suggère que ces algèbres correspondent à des symétries cachées de dimension infinie de la gravité. Nous examinons comment la dynamique du billard est modifiée quand la théorie de gravité originale est formulée sur une variété spatiale compacte de topologie arbitraire, révélant ainsi de fascinantes structures mathématiques appelées galleries. De plus, dans le cadre de la supergravité à onze dimensions, nous utilisons la symétrie hyperbolique conjecturée E10 pour engendrer et classifier certaines solutions cosmologiques (S-branes). Finalement, nous montrons en détail que la supergravité à onze dimensions et la supergravité de type IIA massive sont dynamiquement unifiées dans le contexte d'un modèle sigma géodesique pour une particule se déplaçant sur l'espace quotient de dimension infinie E10/K(E10).<p><p><p>La deuxième partie de cette thèse est consacrée à étudier comment les dualités U en théorie des cordes fournissent des contraintes puissantes sur les corrections quantiques perturbatives et non perturbatives. Ces dualités sont typiquement données par des groupes arithmétiques G(Z) dont il est conjecturé qu'ils préservent l'action effective. Les couplages exacts sont donnés par des fonctions des moduli qui sont manifestement invariantes sous G(Z), et qu'on appelle des formes automorphiques. Nous discutons en détail différentes méthodes de construction de ces formes automorphiques, en insistant particulièrement sur une classe spéciale de fonctions appelées séries d'Eisenstein (non holomorphiques). Nous présentons comme exemples les cas de SL(2,Z) et SL(3,Z), qui sont physiquement pertinents. Nous construisons les séries d'Eisenstein correspondantes et leurs expansions de Fourier (non abéliennes). Nous discutons également la possibilité que certaines séries d'Eisenstein généralisées, qui sont covariantes sous le sous-groupe compact maximal, pourraient jouer un rôle dans la détermination des actions effectives exactes pour les théories incluant des corrections de dérivées supérieures compactifiées sur des tores.<p><p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished
96

The Lie Symmetries of a Few Classes of Harmonic Functions

Petersen, Willis L. 23 May 2005 (has links) (PDF)
In a differential geometry setting, we can analyze the solutions to systems of differential equations in such a way as to allow us to derive entire classes of solutions from any given solution. This process involves calculating the Lie symmetries of a system of equations and looking at the resulting transformations. In this paper we will give a general background of the theory necessary to develop the ideas of working in the jet space of a given system of equations, applying this theory to harmonic functions in the complex plane. We will consider harmonic functions in general, harmonic functions with constant Jacobian, harmonic functions with fixed convexity and a few other subclasses of harmonic functions.
97

Quantum Dynamics Using Lie Algebras, with Explorations in the Chaotic Behavior of Oscillators

Sayer, Ryan Thomas 06 August 2012 (has links) (PDF)
We study the time evolution of driven quantum systems using analytic, algebraic, and numerical methods. First, we obtain analytic solutions for driven free and oscillator systems by shifting the coordinate and phase of the undriven wave function. We also factorize the quantum evolution operator using the generators of the Lie algebra comprising the Hamiltonian. We obtain coupled ODE's for the time evolution of the Lie algebra parameters. These parameters allow us to find physical properties of oscillator dynamics. In particular we find phase-space trajectories and transition probabilities. We then search for chaotic behavior in the Lie algebra parameters as a signature for dynamical chaos in the quantum system. We plot the trajectories, transition probabilities, and Lyapunov exponents for a wide range of the following physical parameters: strength and duration of the driving force, frequency difference, and anharmonicity of the oscillator. We identify conditions for the appearance of chaos in the system.
98

Quasiconformal maps on a 2-step Carnot group

Gardiner, Christopher James 17 July 2017 (has links)
No description available.
99

Nilpotent Class Field Theory

Abramov, Gueorgui 13 January 1999 (has links)
No description available.
100

The classification and dynamics of the momentum polytopes of the SU(3) action on points in the complex projective plane with an application to point vortices

Shaddad, Amna January 2018 (has links)
We have fully classified the momentum polytopes of the SU(3) action on CP(2)xCP(2) and CP(2)xCP(2) xCP(2), both actions with weighted symplectic forms, and their corresponding transition momentum polytopes. For CP(2)xCP(2) the momentum polytopes are distinct line segments. The action on CP(2)xCP(2) xCP(2), has 9 different momentum polytopes. The vertices of the momentum polytopes of the SU(3) action on CP(2)xCP(2) xCP(2), fall into two categories: definite and indefinite vertices. The reduced space corresponding to momentum map image values at definite vertices is isomorphic to the 2-sphere. We show that these results can be applied to assess the dynamics by introducing and computing the space of allowed velocity vectors for the different configurations of two-vortex systems.

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