Orientador: Marcos Benevenuto Jardim / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-10T08:38:10Z (GMT). No. of bitstreams: 1 Prata_DanielaMoura_M.pdf: 537246 bytes, checksum: 34750d4837b03d877cf678e318e84f40 (MD5) Previous issue date: 2008 / Resumo: Nesta dissertação o principal objetivo é introduzir na categoria de representações torcidas de um quiver Q as definições e resultados já co-nhecidos para categorias de representações de quivers. O conceito de reapresentações torcidas foi introduzido por Gothen e King em [11] para estudar problemas envolvendo fibrados vetoriais sobre variedades algébricas. King também mostrou em [16] que, sobre certas condições, as representações semi-estáveis de um quiver são parametrizadas por uma variedade algébrica projetiva, normal, irredutível. Mostramos que o mesmo vale para representações torcidas de quivers. Nosso principal resultado, que 'e original, mostra equivalência entre a categoria de representações M - torcidas de um quiver Q, RepMQ, e a categoria de representações de um quiver ¿Q, Rep , onde Q depende de Q e dos espaços de M. Essa equivalência nos permitiu desenvolver um pouco da teoria já conhecida para Rep ¿Q na linguagem de RepMQ, reescrever resultados clássicos como o Teorema de Gabriel e de Kac para a categoria de representações torcidas e também relacionar RepQ com RepMQ / Abstract: The main goal of this thesis is to introduce for the category of twisted representations of a quiver Q the definitions and results one already knows for categories of representations of quivers. The concept of twisted representations was introduced by Gothen and King in [11] to study problems concerning vector bundles over algebraic varieties. King also showed in [16] that under certain conditions, semi-stable representations of a quiver are parametrized by an irreducible, normal projective algebraic variety. We show that we have the same results for twisted representations. Our main and original result provides an equivalence between the category of twisted representations of a quiver Q, RepMQ, and the category of representations of a quiver Q, Rep ¿Q, where ¿Q depends on Q and on the twisting factors. With this equivalence we developed the existing theory of representations of quivers for twisted representations, we rewrote classical results like Gabriel¿s theorem and Kac¿s theorem for the category of twisted representations and found a relation between RepQ and RepMQ / Mestrado / Algebra / Mestre em Matemática

Orientador: Marcos Benevenuto Jardim / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Científica / Made available in DSpace on 2018-08-13T06:54:55Z (GMT). No. of bitstreams: 1 Silva_VitorMorettoFernandesda_M.pdf: 773065 bytes, checksum: 87c9c9b184da7470d32ab571c3b760d1 (MD5) Previous issue date: 2009 / Resumo: Neste trabalho definimos quivers e discutimos como a categoria de módulos sobre uma álgebra conexa qualquer pode ser associada à categoria de representa equações de um quiver. Estudamos também o sistema de raízes da forma quadrática de Cartan associada a um quiver, que tem bijeção com os vetores dimensão de representação indecomponíveis. Estudamos a demonstração do Teorema de Gabriel, que caracteriza todos os quivers que têm quantidade finita de representações indecomponíveis a partir da forma de Cartan. O Teorema de Gabriel também define quando um quiver tem tipo manso. Apresentamos também a demonstração do Teorema de Ovsienko, que sob certas condições, caracteriza os quivers com relações que têm quantidade finita de representações indecomponíveis a partir da forma de Brenner / Abstract: In this work, we define quivers and their representations, and discuss how the category of modules over an arbitrary connected associative algebra can be associated to the category of representations of a quiver. We also study the root system of the Cartan quadratic form associated to a quiver, which is bijective with the set of dimension vectors for which an indecomposable representation exists. The proof of Gabriel's Theorem, which characterizes all quivers with finitely many indecomposable representations in terms of its Cartan form, is presented. Gabriel's Theorem also defines when a quiver is of tame time. Finally, we also describe a theorem due to Ovsienko which, under certain conditions, characterize the quivers with relations that admit only finitely many indecomposable representations in terms of its Brenner form / Mestrado / Mestre em Matemática

Techniques from the theory of matrix problems have proven to be helpful for studying problems within representation theory. In particular, matrix problems are well suited to use in problems related to classifying indecomposable representations of quivers and of posets. However, throughout the literature, there are many different types of matrix problems and little clarification of the relationships between them. In this thesis, we choose six types of matrix problems, place them all within a common framework and find correspondences between them. Moreover, we show that their use in the classification of finite-dimensional representations of quivers and posets are, in general, well-founded. Additionally, we investigate a direct relationship between the problem of classifying quiver representations and the problem of classifying poset representations.

A new connection between combinatorics and noncommutative algebra is established by relating a certain class of directed graphs to noncommutative Koszul algebras. The directed graphs in this class are called full graphs and are defined by a set of criteria on the edges. The structural properties of full graphs are studied as they relate to the edge criteria. A method is introduced for generating a Koszul algebra Lambda from a full graph G. The properties of Lambda are examined as they relate to the structure of G, with special attention being given to the construction of a projective resolution of certain semisimple Lambda-modules based on the structural properties of G. The characteristics of the Koszul algebra Lambda that is derived from the product of two full graphs G' and G' are studied as they relate to the properties of the Koszul algebras Lambda' and Lambda' derived from G' and G'. / Ph. D.

Orientador: Marcos Benevenuto Jardim / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Científica / Made available in DSpace on 2018-08-17T21:21:11Z (GMT). No. of bitstreams: 1 Santos_RodrigoPiresdos_M.pdf: 1008454 bytes, checksum: e5ec1fd87b26efb201ece05c20531374 (MD5) Previous issue date: 2011 / Resumo: Apresentamos uma introdução aos conceitos de geometria complexa necessários à compreensão da correspondência Hitchin-Kobayashi. Enunciamos e provamos que todo fibrado que admite uma conexão de Hermite-Einstein é poliestável. Em seguida, discutimos resultados sobre Q-fibrados e enunciamos uma correspondência Hitchin-Kobayashi para esse caso. Por último, temos um resultado do autor que relaciona a estabilidade de fibrados com a estabilidade de Q-fibrados / Abstract: We present an introduction to the concepts of complex geometry necessary to the comprehension of the Hitchin-Kobayashi correspondence. We state and prove that every holomorphic vector bundle which admits a Hermite-Einstein connexion is polystable. Then, we discuss results regarding quiver bundles and state a Hitchin-Kobayashi correspondence for this case. Finally, we state and prove an author's result which relates the stability of vector bundles with the stability of quiver bundles / Mestrado / Geometria Diferencial / Mestre em Matemática

Orientador: Adriano Adrega de Moura / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Cientifica / Made available in DSpace on 2018-08-18T00:34:15Z (GMT). No. of bitstreams: 1 Brito_MatheusBatagini_M.pdf: 1577922 bytes, checksum: 6e151b2dd08dad43a9a5c9840dd36514 (MD5) Previous issue date: 2011 / Resumo: Na presente dissertação estudamos dois exemplos de relacionamento da teoria de álgebras de cluster com teoria de representações. A saber, estudamos os principais resultados dos artigos [5, 26]. O primeiro é uma relação entre álgebras de cluster e representações de certos quivers com relações que também estão relacionadas com triangulações de polígonos regulares. O segundo exemplo trata de um modelo de categorificação monoidal de certas álgebras de cluster via teoria de representações de dimensão finita do grupo quântico associado a uma álgebra de Kac-Moody afim de tipo A / Abstract: In this dissertation we study two examples of interplay between the theory of cluster algebras from one side and representation theory on the other. Namely, we study the main results of the articles [5, 26]. The first one is a relation between cluster algebras of type A and representations of certain quiver with relations which are also related to triangulations of regular polygons. The second example concerns a model of monoidal categorification of certain cluster algebras via finite dimensional representation theory of the quantum group associated to an affine Kac- Moody algebra of type A / Mestrado / Algebra / Mestre em Matemática

Orientador: Marcos Benevenuto Jardim / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Científica / Made available in DSpace on 2018-08-24T04:44:46Z (GMT). No. of bitstreams: 1 Silva_VitorMorettoFernandesda_D.pdf: 591420 bytes, checksum: aa507d8eca04760207f4e88b0636be83 (MD5) Previous issue date: 2013 / Resumo: Neste trabalho estudamos uma equivalência entre mônadas e representações de quivers. No segundo capítulo apresentamos um critério de decomponibilidade para mônadas lineares e, em particular, para instantons. No terceiro capítulo apresentamos exemplos de mônadas sobre espaços projetivos de dimensão par que generalizam a mônada de Horrocks-Mumford em P4 / Abstract: In this work, we study an equivalence between monads and representations of quivers. The second chapter presents a decomposability criterion for linear monads and, in particular, for instantons. In the third chapter we present new examples of monads on projective spaces of even dimension, which generalize the Horrocks-Mumford monad on P4 / Doutorado / Matematica / Doutor em Matemática

The work of this thesis focuses primarily on non-commutative algebras and actions of Hopf algebras. Specifically, we study the possible H-module algebra structures which can be imposed on path algebras of quivers, for a variety of Hopf algebras, H, and then given a possible action, classify the invariant ring. A Hopf algebra is a bialgebra (H, μ, η, ∆, ε) together with an antipode S : H → Hop which is compatible with the counit, ε, of H. A quiver is a directed graph, and the path algebra kQ of a quiver Q is a vector space where all the paths of the quiver form a basis, and multiplication is given by concatenation of paths whenever possible, and zero otherwise. In their paper, [9], Kinser and Walton classify Hopf actions of a specific family of Hopf algebras called a Taft algebras, T(n), on path algebras of loopless, finite, Schurian quivers. In this thesis, we extend their result to path algebras of any finite quiver and classify the invariant subring, kQT(n), in the case where the group like element g ∈ T(n) acts transitively on Q0. In the future, we hope that the ideas presented in this work extend to a classification of quantum groups, such as uq(sl2), acting on path algebras of finite quivers.

This thesis studies derived equivalences between total spaces of vector bundles and dg-quivers. A dg-quiver is a graded quiver whose path algebra is a dg-algebra. A quiver with superpotential is a dg-quiver whose differential is determined by a "function" Φ. It is known that the bounded derived category of representations of quivers with superpotential with finite dimensional cohomology is a Calabi- Yau triangulated category. Hence quivers with superpotential can be viewed as noncommutative Calabi- Yau manifolds. One might then ask if there are derived equivalences between Calabi-Yau manifolds and quivers with superpotential. In this thesis, we answer this question and, generalizing Bridgeland [15], give a recipe on how to construct such derived equivalences.

Orientador: Marcos Benevenuto Jardim / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Científica / Made available in DSpace on 2018-08-20T05:02:36Z (GMT). No. of bitstreams: 1 Prata_DanielaMoura_D.pdf: 839425 bytes, checksum: 24b3dac76766d8c843d040b951a4376a (MD5) Previous issue date: 2012 / Resumo: Neste trabalho relacionamos algumas classes de fibrados vetoriais...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: In this work we relate some classes of vector bundles on...Note: The complete abstract is available with the full electronic document / Doutorado / Matematica / Doutor em Matemática