We study aspects of noncommutative geometry on hyperbolic dynamical systems known as Smale spaces. In particular, there are two C*-algebras, defined on the stable and unstable groupoids arising from the hyperbolic dynamics. These give rise to two additional crossed product C*-algebras known as the stable and unstable Ruelle algebras. We show that the Ruelle algebras exhibit noncommutative Poincaré duality. As a consequence we obtain isomorphisms between the K-theory and K-homology groups of the stable and unstable Ruelle algebras. A second result defines spectral triples on these C*-algebras and we show that the spectral dimension recovers the topological entropy of the Smale space itself. Finally we define a natural Fredholm module on the Ruelle algebras in the special case that the Smale space is a shift of finite type. Using unitary operators arising from the Pimsner-Voiculescu sequence we compute the index pairing with our Fredholm module for specific examples.

Given a C*-algebra $A$ endowed with an action $\alpha$ of $\R$ and an $\alpha$-invariant trace $\tau$, there is a canonical dual trace $\widehat \tau$ on the crossed product $A \rtimes_\alpha \R$. This dual trace induces (as would any suitable trace) a real-valued homomorphism $\widehat \tau_* : K_0(A \rtimes_\alpha \R) \to \R$ on the even $K$-theory group. Recall there is a natural isomorphism $\phi_\alpha^i : K_i(A) \to K_{i+1}(A \rtimes_\alpha \R)$, the Connes-Thom isomorphism. The attraction of describing $\widehat \tau_* \circ \phi_\alpha^1$ directly in terms of the generators of $K_1(A)$ is clear. Indeed, the paper where the isomorphisms $\{\phi_\alpha^0,\phi_\alpha^1\}$ first appear sees Connes show that $\widehat \tau_* \phi_\alpha^1[u] = \frac{1}{2 \pi i} \tau(\delta(u) u^*)$, where $\delta = \frac{d}{dt} \big|_{t=0} \alpha_t(\cdot)$ and $u$ is any appropriate unitary. A careful proof of the aforementioned result occupies a central place in this thesis. To place the result in its proper context, the right-hand side is first considered in its own right, i.e., in isolation from mention of the crossed-product. A study of 1-parameter dynamical systems and exterior equivalence is undertaken, with several useful technical results being proven. A connection is drawn between a lemma of Connes on exterior equivalence and projections, and a quantum-mechanical theorem of Bargmann-Wigner. An introduction to the Connes-Thom isomorphism is supplied and, in the course of this introduction, a refined version of suspension isomorphism $K_1(A) \to K_0(\susp A)$ is formulated and proven. Finally, we embark on a survey of unbounded traces on C*-algebras; when traces are allowed to be unbounded, there is inevitably a certain amount of hard, technical work needed to resolve various domain issues and justify various manipulations. / Graduate / 0280

Thesis (Ph. D.)--University of Oregon, 2007. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 107-108). Also available for download via the World Wide Web; free to University of Oregon users.

Techn. Univ., Habil.-Schr.--Clausthal, 2000. / Literaturverz. S. [256] - 262.

abstract: In this thesis, I investigate the C*-algebras and related constructions that arise from combinatorial structures such as directed graphs and their generalizations. I give a complete characterization of the C*-correspondences associated to directed graphs as well as results about obstructions to a similar characterization of these objects for generalizations of directed graphs. Viewing the higher-dimensional analogues of directed graphs through the lens of product systems, I give a rigorous proof that topological k-graphs are essentially product systems over N^k of topological graphs. I introduce a "compactly aligned" condition for such product systems of graphs and show that this coincides with the similarly-named conditions for topological k-graphs and for the associated product systems over N^k of C*-correspondences. Finally I consider the constructions arising from topological dynamical systems consisting of a locally compact Hausdorff space and k commuting local homeomorphisms. I show that in this case, the associated topological k-graph correspondence is isomorphic to the product system over N^k of C*-correspondences arising from a related Exel-Larsen system. Moreover, I show that the topological k-graph C*-algebra has a crossed product structure in the sense of Larsen. / Dissertation/Thesis / Ph.D. Mathematics 2011

Orientador: Plamen Koshlukov / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatisticas e Computação Cientifica / Made available in DSpace on 2018-08-07T02:02:57Z (GMT). No. of bitstreams: 1 BrandaoJunior_AntonioPereira_D.pdf: 1947392 bytes, checksum: a2dae6805cd5224410f82d2eaaa472fc (MD5) Previous issue date: 2006 / Resumo: Neste trabalho apresentamos um estudo sobre polinômios centrais graduados e polinômios centrais com involução para algumas álgebras importantes na PI-teoria sobre corpos infinitos. Mais precisamente, descrevemos os polinômios centrais Z2-graduados para as álgebras M2 (K) (matrizes 2 x 2 sobre um corpo K), Ml,l (5), onde 5 é uma álgebra supercomutativa (em particular, obtemos o caso Ml,l(E)), e E 0 E. Para Ml,1(5), apresentamos antes uma classificação em termos de identidades Z2-graduadas. Aqui E é a álgebra de Grassmann de dimensão infinita com unidade e Ml,1(5) é a subálgebra de M2(5), cujos elementos são as matrizes que têm a diagonal principal com elementos de 50, a componente par (central) de 5, e a diagonal secundária com elementos de 51, a componente ímpar (anticomutativa) de 5. Descrevemos também os polinômios centrais graduados para as álgebras Mn(K) (matrizes nxn sobre K), considerando suas graduações naturais pelos grupos cíclicos, e finalménte os polinômios centrais com involução para M2(K), considerando as involuções transposta e simplética / Abstract: In this thesis we study graded central polynomials and central polynomials with involution for some important algebras in the theory of algebras with polynomial identities, over infinite fields. Namely we describe the Z2-graded central polynomials for the algebras M2(K) (the 2 x 2 matrices over the field K), Ml,1(5), where 5 is an arbitrary supercommutative algebra. In particular we obtain the cases Ml,l (E), and furthermore E 0 E. For the case Ml,l (5) we first give a classification in terms of Z2-graded identities. Here E stands for the infinite dimensional Grassmann algebra with 1. AIso Ml,1(5) is the subalgebra of M2(5) with elements the matrices whose main diagonal has entries from 50, the even (central) component of 5, and off-diagonal entries from 51, the odd (anticommutative) component of 5. We also describe the graded central polynomials for the algebras Mn(K), the n x n matrices over K, considering their natural gradings by cyclic groups, and finally the central polynomials with involution for M2 (K), considering the transpose and the symplectic involutions / Doutorado / Algebra / Doutor em Matemática

Sejam K um corpo algebricamente fechado, A uma K-álgebra básica conexa de dimensão finita sobre K e ê=(e_1,e_2,... ,e_n) um conjunto completo de idempotentes ortogonais, primitivos e ordenados de A. O conjunto dos módulos estandares é o conjunto Delta ={ D_1, ..., D_n }, onde D_i é o quociente maximal do A-módulo projetivo P_i com fatores de composição simples S_j, com j\\leq i, F(Delta) é a subcategoria plena de mod A dos módulos têm uma Delta-filtração. Se A_A esta em F(Delta) diz-se que A é uma álgebra estandarmente estratificada. Se, além disso, para cada elemento em Delta vale que End_A(D_i) é isomorfo a K diz-se que A é uma álgebra álgebra quase-hereditária. Nesta dissertação estudamos as propriedades de F(Delta), especialmente quando A é estandarmente estratificada, e algumas condições necessárias e suficientes para que A seja quase-hereditária. / Let K be an algebraically closed field, A a basic, connected, finite dimensional K-algebra and ê=(e_1,e_2,...,e_n) a complete set of ordered primitive orthogonal idempotents of A. The set of standard modules is the set Delta={D_1, ..., D_n}, where D_i is the maximal factor submodule of P_i whose composition factors are isomorphic to S_j, for j\\leq i. We denote by F(Delta) the full subcategory of mod A containing the modules which are filtered by modules in Delta. If iA_A is in F(Delta) we say that A is standardly stratified. Moreover, if End_A(D_i) is isomorphic with K, for each element in Delta we say that A is quasi hereditary. In this work we study the properties of the category F(Delta), especially when A is stardardly stratified, and some necessary and sufficient conditions to A be quasi hereditary.

Orientadores: Adriano Adrega de Moura, Daniel Ken Nakano / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Científica / Made available in DSpace on 2018-08-22T17:19:06Z (GMT). No. of bitstreams: 1 Macedo_TiagoRodrigues_D.pdf: 1593692 bytes, checksum: 0f44184671f53844f40df83e883c05ea (MD5) Previous issue date: 2013 / Resumo: Nesta tese nós estudamos dois problemas principais. O primeiro problema aborda extensões de módulos para álgebras de corrente associadas a álgebras de Lie simples, complexa e de dimensão finita. Primeiro nós calculamos 1-extensões entre módulos simples de dimensão finita dessas álgebras, recuperando parcialmente um resultado de Kodera. A seguir nós desenvolvemos uma técnica para calcular extensões mais altas entre módulos simples, com a qual nós calculamos certas 2-extensões. Por fim nós mostramos que os grupos de cohomologia da álgebra de corrente são isomorfos aos da álgebra de Lie simples associada a ela, confirmando uma afirmação de Feigin. Essa parte da tese foi desenvolvida em colaboração com B. Boe, C. Drupieski e D. Nakano. O segundo problema aborda certa classe de módulos para hiperálgebras de álgebras de corrente. Quando a álgebra de Lie a qual a álgebra de corrente é associada é de tipo ADE, nós mostramos que módulos de Weyl locais são isomorfos a certos módulos de Demazure, estendendo para característica positiva um resultado de Fourier-Littelmann. Em geral, nós estendemos um resultado de Naoi, provando que módulos de Weyl locais admitem uma bandeira de Demazure, i.e., uma filtração cujos fatores são isomorfos a módulos de Demazure. Usando esse resultado, nós provamos uma conjectura de Jakelic-Moura que afirma que o caracter dos módulos de Weyl locais para hiperálgebras de laços são independentes do corpo base, desde que este seja algebricamente fechado / Abstract: In this thesis we consider two main problems. The first problem concerns extensions between simple modules for current algebras associated to complex, simple, finite-dimensional Lie algebras. To begin, we compute 1-extensions between finite-dimensional simple modules, partially recovering a result due to Kodera. Then we develop a technique aimed to compute higher extensions, and which we use to compute 2-extensions between certain simple modules. Finally we prove that cohomology groups of current algebras are isomorphic to the cohomology groups of its underlying simple Lie algebra, a result stated by Feigin. This part of the thesis arises from collaboration with B. Boe, C. Drupieski and D. Nakano. The second problem is concerned with the study of certain classes of modules for hyper algebras of current algebras. In the case that the underlying Lie algebra is simply laced, we show that local Weyl modules are isomorphic to certain Demazure modules, extending to positive characteristic a result due to Fourier-Littelmann. More generally, we extend a result of Naoi by proving that local Weyl modules admit a Demazure flag, i.e., a filtration with factors isomorphic to Demazure modules. Using this, we prove a conjecture of Jakelic-Moura stating that the character of local Weyl modules for hyper loop algebras are independent of the (algebraically closed) ground field / Doutorado / Matematica / Doutor em Matemática

Orientador: Jorge Tulio Ascui Mujica / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-21T23:57:51Z (GMT). No. of bitstreams: 1 Santos_ElisaReginados_D.pdf: 2025728 bytes, checksum: 9a431cb6242382a2edc9a78d9a7467e4 (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 / Doutor em Matemática

Orientador: Adriano Adrega de Moura / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Científica / Made available in DSpace on 2018-08-20T09:20:36Z (GMT). No. of bitstreams: 1 Ferreira_GilmardeSousa_M.pdf: 480832 bytes, checksum: 42db64084fe99183a4fb95f90cd9a833 (MD5) Previous issue date: 2012 / Resumo: Nessa dissertação estudamos certas categorias de módulos graduados para uma classe de álgebras de Lie que inclui as álgebras de correntes. Em particular, estudamos diversas propriedades homológicas dessas categorias tais como resoluções projetivas e o espaço de extensões entre seus objetos simples. Em certas situações, os resultados levam ao estabelecimento de um relacionamento com álgebras de Koszul. O estudo é baseado em artigos recentes de Vyjayanthi Chari e seus co-autores / Abstract: In this dissertation, we study certain categories of graded modules for a class of Lie algebras which include current algebras. In particular, we study several homological properties of these categories such as projective resolutions and the space of extensions between two given simple objects. Under certain conditions, these results establish a relationship with Koszul algebras. The study is based on recent papers by Vyjayanthi Chari and her co-authors / Mestrado / Matematica / Mestre em Matemática