In this dissertation, let B be a triangulated category and let D be an extension-closed subcategory of B. First, we give some new characterizations of an Auslander-Reiten triangle in D, which yields some necessary and sufficient conditions for D to have Auslander-Reiten triangles. Next, we study when an Auslander-Reiten triangle in B induces an Auslander-Reiten triangle in D. As an application, we study Auslander-Reiten triangles in a triangulated category with a t-structure. In case the t-structure has a t-hereditary heart, we establish the connection between the Auslander-Reiten triangles in B and the Auslander-Reiten sequences in the heart. Finally, we specialize to the bounded derived category of all modules of a noetherian algebra over a complete local noetherian commutative ring. Our result generalizes the corresponding result of Happel’s in the bounded derived category of finite dimensional modules of a finite dimensional algebra over an algebraically closed field.

This thesis consists of three parts. In the first part we look at Hopf algebras. We classify pointed rank one Hopf algebras over fields of prime characteristic which are generated as algebras by the first term of the coradical filtration. These Hopf algebras were classified by Radford and Krop for fields of characteristic zero. We obtain three types of Hopf algebras presented by generators and relations. The third type is new and has not previously appeared in literature. The second part of this thesis deals with Auslander-Reiten theory of finitedimensional algebras over fields. We consider G-transitive algebras and develop necessary conditions for them to have Auslander-Reiten components with Euclidean tree class. Thereby a result in [F3, 4.6] is corrected and generalized. We apply these results to G-transitive blocks of the universal enveloping algebras of restricted p-Lie algebras. Finally we deduce a condition for a smash product of a local basic algebra Λ with a commutative semi-simple group algebra to have components with Euclidean tree class, in terms of the components of the Auslander-Reiten quiver of Λ. In the last part we introduce and analyze Auslander-Reiten components for the bounded derived category of a finite-dimensional algebra. We classify derived categories whose Auslander-Reiten quiver has either a finite stable component or a stable component with finite Dynkin tree class or a bounded stable component. Their Auslander-Reiten quiver is determined. We use these results to show that certain algebras are piecewise hereditary. Also a necessary condition for the existence of components of Euclidean tree class is deduced. We determine components that contain shift periodic complexes.

Made available in DSpace on 2015-03-26T13:45:37Z (GMT). No. of bitstreams: 1 texto completo.pdf: 446590 bytes, checksum: 8c515244f3fa52b730a12770059cccea (MD5) Previous issue date: 2014-02-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this paper, we prove the existence of Auslander-Reiten triangles (TAR) for compact objects in triangulated categories compactly generated. The prove presented is an application of the theorem of Brown representability in derived categories for compact complex, ie, given Z be a compact and indecomposable complex, we show that there is a Auslander-Reiten triangle X->U->Y->v->Z->w->TX in K-b(^) which is equivalent to D(^), where ^ is a finite-dimensional k-algebra over an algebraically closed field. Furthermore, we have that a triangle Auslander-Reiten wihch start with the projective resolution of a indecomposable and non-injective module T-¹pM->alfa->Y->Beta->(pDM)*->y->pM induces an Auslander-Reiten sequence(SAR) 0->M->alfa¹->Cok¹ (Y)-> beta¹->Tr DM->0. How Mod(^) and D(^) are Krull-Schmidt, and classes of indecomposable objects and generators of irreducible morphisms of these categories occur in the SAR's and TAR's, respectively, these results provide us with a skillful tool to know the structures Mod(^) and D(^) of k-algebras. Moreover, we present examples using the representation theory of quivers of an algebra of paths. / Neste trabalho, apresentamos uma prova da existência de triângulos de Auslander-Reiten(TAR) para objetos compactos em categorias trianguladas compactamente geradas. A prova apresentada é uma aplicação do Teorema da Representabilidade de Brown em categorias derivadas para complexos compactos, ou seja, dado Z um complexo compacto e indecomponíveL mostramos que existe um triângulo X->U->Y->v->Z->w->TX de Auslander-Reiten em K-b(^) que é equivalente à Db(^), onde ^ é uma k-álgebra de dimensão finita sobre um corpo algébricamente fechado. Além disso, temos que um triângulo de Auslander-Reiten que começa com a resolução projetiva de um módulo indecomponível não-injetivo T-¹pM->alfa->Y->Beta->(pDM)*->y->pM induz uma sequência de Auslander-Reiten(SAR) 0->M->alfa¹->Cok¹ (Y)-> beta¹->Tr DM->0. Como MOd(^) e D(^) são Krull-Remak-Schmidt, e as classes de objetos inde- componíveis e os geradores de morfismos irredutíveis destas categorias ocorrem nas SAR's e nos TAR's, respectivamente, estes resultados nos fornecem uma hábil ferramenta para conhecer as estruturas de Mod(^) e D(^) de k-álgebras. Além disso, apresentamos exemplos utilizando a teoria de representação de quivers de uma álgebra de caminhos.

Les algèbres de Temperley-Lieb originales, aussi dites régulières, apparaissent dans de nombreux modèles statistiques sur réseau en deux dimensions: les modèles d'Ising, de Potts, des dimères, celui de Fortuin-Kasteleyn, etc. L'espace d'Hilbert de l'hamiltonien quantique correspondant à chacun de ces modèles est un module pour cette algèbre et la théorie de ses représentations peut être utilisée afin de faciliter la décomposition de l'espace en blocs; la diagonalisation de l'hamiltonien s'en trouve alors grandement simplifiée. L'algèbre de Temperley-Lieb diluée joue un rôle similaire pour des modèles statistiques dilués, par exemple un modèle sur réseau où certains sites peuvent être vides; ses représentations peuvent alors être utilisées pour simplifier l'analyse du modèle comme pour le cas original. Or ceci requiert une connaissance des modules de cette algèbre et de leur structure; un premier article donne une liste complète des modules projectifs indécomposables de l'algèbre diluée et un second les utilise afin de construire une liste complète de tous les modules indécomposables des algèbres originale et diluée. La structure des modules est décrite en termes de facteurs de composition et par leurs groupes d'homomorphismes. Le produit de fusion sur l'algèbre de Temperley-Lieb originale permet de «multiplier» ensemble deux modules sur cette algèbre pour en obtenir un autre. Il a été montré que ce produit pouvait servir dans la diagonalisation d'hamiltoniens et, selon certaines conjectures, il pourrait également être utilisé pour étudier le comportement de modèles sur réseaux dans la limite continue. Un troisième article construit une généralisation du produit de fusion pour les algèbres diluées, puis présente une méthode pour le calculer. Le produit de fusion est alors calculé pour les classes de modules indécomposables les plus communes pour les deux familles, originale et diluée, ce qui vient ajouter à la liste incomplète des produits de fusion déjà calculés par d'autres chercheurs pour la famille originale. Finalement, il s'avère que les algèbres de Temperley-Lieb peuvent être associées à une catégorie monoïdale tressée, dont la structure est compatible avec le produit de fusion décrit ci-dessus. Le quatrième article calcule explicitement ce tressage, d'abord sur la catégorie des algèbres, puis sur la catégorie des modules sur ces algèbres. Il montre également comment ce tressage permet d'obtenir des solutions aux équations de Yang-Baxter, qui peuvent alors être utilisées afin de construire des modèles intégrables sur réseaux. / The original Temperley-Lieb algebra, also called regular, appears in numerous integrable statistical models on two dimensional lattices: the Ising model, the Potts model, the dimers model, the Fortuin-Kasteleyn model, etc. The Hilbert space of the corresponding quantum hamiltonian is then a module over this algebra; its representation theory can be used to split this space in a direct sum of smaller spaces, and thus block diagonalize the corresponding quantum model. The dilute Temperley-Lieb algebra plays a similar role for dilute models, for instance those where lattice sites can be empty; its representation theory thus plays a similar role for these models. However, doing this requires a detailled knowledge of its modules and their structure; the first paper presents a complete list of the projective indecomposable modules for the dilute Temperley-Lieb algebra and a second constructs a complete set of indecomposable modules for both the regular and dilute algebras. In both articles the structure of the modules are exposed through their composition factors and homomorphism groups. The fusion product on the original Temperley-Lieb algebra defines how two modules can be «multiplied» together to obtain a module. It has been shown in some cases that this product can be used to simplify the block diagonalization of quantum hamiltonians, and some speculate that it could be used to determine the continuum limit of the models. A third paper defines a straightforward generalization of this product for the dilute algebra, then introduces an efficient way of computing it. It then calculates this product for the most common classes of indecomposable modules for both the original and dilute algebras; this fills a hole in the known fusion rules for the original algebra that were left out of previous calculations. Finally, it happens that the Temperley-Lieb algebras can be grouped together in a braided monoidal category, whose structure is compatible with the fusion product described above. The fourth article builds explicitly this braiding, both for the Temperley-Lieb category, and for its module category. It also shows how this braiding can be used to obtain solutions to the Yang-Baxter equation, which can then be used to build integrable lattice models.