Orientador: Plamen Emilov Koshlukov / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatisticas e Computação Cientifica / Made available in DSpace on 2018-08-07T19:30:45Z (GMT). No. of bitstreams: 1 Alves_SergioMota_D.pdf: 708263 bytes, checksum: 1d9ec0b24db06ea81853a6e7d6794b18 (MD5) Previous issue date: 2006 / Resumo: As álgebras verbalmente primas são bem conhecidas em característica 0, já sobre corpos de característica p > 2 pouco sabemos sobre elas. Nesse trabalho vamos discutir algumas diferenças entre estes dois casos de característica sobre corpos infinitos. Iniciamos mostrando que o Teorema do Produto Tensorial de Kemer e duas de suas conseqüências não podem ser transportados para corpos infinitos de característica positiva p > 2. Em seguida, discutiremos algumas propriedades envolvendo as álgebras Aa;b, a saber, mostraremos que as álgebras Aa;b e Ma+b(E) não são PI-equivalentes e que as álgebras Aa;a e Ma;a (E) ­ não são PI-equivalentes, e apresentaremos um resultado que enfatiza a importância dos monômios na determinação do ideal das identidades das álgebras Zn £ Z2-graduadas Aa;b em característica positiva. Por ¯m, apresentaremos modelos genéricos e calcularemos a dimensão de Gelfand-Kirillov para as álgebras relativamente livres de posto m nas variedades determinadas pelas álgebras E ­ E, Aa;b e Ma;a(E) ­ E. Como conseqüência, obteremos a prova da não PI- equivalência entre álgebras importantes para PI-teoria em característica positiva / Abstract: The verbally prime algebras are well understood in characteristic 0 while over a field of characteristic p > 2 little is known about them. In this work we discuss some sharp di®erences between these two cases for the characteristic. First we show that the so-called Kemer's Tensor Product Theorem and two of its consequences cannot be extended for infnite fields of positive characteristic p > 2. Afterwards we prove that the algebras Aa;b and Ma+b(E) are not PI equivalent, while the algebras Aa;a and Ma;a(E) ­ E are PI equivalent. Moreover we obtain a result showing the importance of the monomials in the Zn £ Z2-graded T-ideal of the algebra Aa;b. Finally, we exhibit constructions of generic models. By using these models we compute the Gelfand-Kirillov dimension of the relatively free algebras of rank m in the varieties generated by E ­E, Aa;b, and Ma;a(E)­E. As consequence we obtain the PI non equivalence of important algebras for the PI theory in positive characteristic / Doutorado / Algebra / Doutor em Matemática

Orientadores: Dharam Vir Ahluwalia, Pedro Cunha de Holanda / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-27T16:17:02Z (GMT). No. of bitstreams: 1 Souza_GustavoSalinasde_M.pdf: 1015499 bytes, checksum: c37e17dd874ddddc3fa8389ff81fc905 (MD5) Previous issue date: 2015 / Resumo: O presente trabalho é dedicado a um estudo sistemático das representações dos grupos HOM(2) e SIM(2), que são subgrupos do grupo de Lorentz. É sabido que teorias cujas simetrias são descritas por tais subgrupos preservam a constância da velocidade da luz, esse fato sendo referido como Very Special Relativity. É mostrado que existem representa ções de HOM(2) e SIM(2) redutíveis e de dimensão nita, que portanto não podem ser obtidas inteiramente de representações irredutíveis. Estas são obtidas diretamente das representações das álgebras de Lie hom(2) e sim(2), usando o conhecimento dos grupos de cobertura universal de HOM(2) e SIM(2), que também são apresentados no texto / Abstract: The present work is devoted to a systematic study of the representations of the groups HOM(2) and SIM(2), which are subgroups of the Lorentz group. Theories with symmetries given by these subgroups are known to preserve the constancy of the speed of light, this fact being referred as Very Special Relativity. It is shown that there are nitedimensional reducible representations of HOM(2) and SIM(2) that are not completely reducible, and thus cannot be obtained entirely from irreducible representations. These are obtained directly from the representations of the Lie algebras hom(2) and sim(2), using the knowledge of the universal covering groups of HOM(2) and SIM(2), which are also presented in the text / Mestrado / Física / Mestre em Física

Nesta tese estudamos dois problemas em digrafos: um problema de empacotamento e um problema de contagem. Estudamos o problema de empacotamento máximo de arborescências no digrafo aleatório D(n,p), onde cada possvel arco é inserido aleatoriamente ao acaso com probabilidade p = p(n). Denote por (D(n,p)) o maior inteiro possvel 0 tal que, para todo 0 l , temos ^(l-1)_i=0 (l-i)|{v in d^in(v) = i}| Provamos que a quantidade máxima de arborescências em D(n,p) é (D(n,p)) assintoticamente quase certamente. Nós também mostramos estimativas justas para (D(n, p)) para todo p [0, 1]. As principais ferramentas que utilizamos são relacionadas a propriedades de expansão do D(n, p), o comportamento do grau de entrada do digrafo aleatório e um resultado clássico de Frank que serve como ligação entre subpartições em digrafos e a quantidade de arborescências. Para o problema de contagem, estudamos a densidade de subtorneios fortemente conexos com 5 vértices em torneios grandes. Determinamos a densidade assintótica máxima para 5 torneios bem como as famlias assintóticas extremais de cada torneios. Como subproduto deste trabalho caracterizamos torneios que são blow-ups recursivos de um circuito orientado com 3 vértices como torneios que probem torneios especficos de tamanho 5. Como principal ferramenta para esse problema utilizados a teoria de álgebra de flags e configurações combinatórias obtidas através do método semidefinido. / In this thesis we study two problems dealing with digraphs: a packing problem and a counting problem. We study the problem of packing the maximum number of arborescences in the random digraph D(n,p), where each possible arc is included uniformly at random with probability p = p(n). Let (D(n,p)) denote the largest integer 0 such that, for all 0 l , we have ^(l-1)_i=0 (l-i)|{v in d^in(v) = i}|. We show that the maximum number of arc-disjoint arborescences in D(n, p) is (D(n, p)) asymptotically almost surely. We also give tight estimates for (D(n, p)) for every p [0, 1]. The main tools that we used were expansion properties of random digraphs, the behavior of in-degree of random digraphs and a classic result by Frank relating subpartitions and number of arborescences. For the counting problem, we study the density of fixed strongly connected subtournaments on 5 vertices in large tournaments. We determine the maximum density asymptotically for five tournaments as well as unique extremal sequences for each tournament. As a byproduct of this study we also characterize tournaments that are recursive blow-ups of a 3-cycle as tournaments that avoid three specific tournaments of size 5. We use the theory of flag algebras as a main tool for this problem and combinatorial settings obtained from semidefinite method.

There is a long history of interesting connections between topological dynamical systems and C*-algebras. Iterated function systems are an important topic in dynamics, but the diversity of these systems makes it challenging to develop an associated class of C*-algebras. Kajiwara and Watatani were the first to construct a C*-algebra from an iterated function system. They used an algebraic approach involving Cuntz-Pimsner algebras; however, when investigating properties such as ideal structure, they needed to assume that the functions in the system are the inverse branches of a continuous map. This excludes many famous examples, such as the standard functions used to construct the Siérpinski Gasket. In this thesis, we provide a construction of an inductive limit of étale equivalence relations for a broad class of affine iterated function systems, including the Siérpinski Gasket and its relatives, and consider the associated C*-algebras. This approach provides a more dynamical perspective, leading to interesting results that emphasize how properties of the dynamics appear in the C*-algebras. In particular, we show that the C*-algebras are isomorphic for conjugate systems, and find ideals related to the open set condition. In the case of the Siérpinski Gasket, we find explicit isomorphisms to subalgebras of the continuous functions from the attractor to a matrix algebra. Finally, we consider the K-theory of the inductive limit of these algebras. / Graduate

Un outil clé dans la théorie des représentations p-adiques est l'algèbre d'Iwasawa, construit par Iwasawa pour étudier les nombres de classes d'une tour de corps de nombres. Pour un nombre premier p, l'algèbre d'Iwasawa d'un groupe de Lie p-adique G, est l'algèbre de groupe G complétée non-commutative. C'est aussi l'algèbre des mesures p-adiques sur G. Les objets provenant de groupes semi-simples, simplement connectés ont des présentations explicites comme la présentation par Serre des algèbres semi-simples et la présentation de groupe de Chevalley par Steinberg. Dans la partie I, nous donnons une description explicite des certaines algèbres d'Iwasawa. Nous trouvons une présentation explicite (par générateurs et relations) de l'algèbre d'Iwasawa pour le sous-groupe de congruence principal de tout groupe de Chevalley semi-simple, scindé et simplement connexe sur Z_p. Nous étendons également la méthode pour l'algèbre d'Iwasawa du sous-groupe pro-p Iwahori de GL (n, Z_p). Motivé par le changement de base entre les algèbres d'Iwasawa sur une extension de Q_p nous étudions les représentations p-adiques globalement analytiques au sens d'Emerton. Nous fournissons également des résultats concernant la représentation de série principale globalement analytique sous l'action du sous-groupe pro-p Iwahori de GL (n, Z_p) et déterminons la condition d'irréductibilité. Dans la partie II, nous faisons des expériences numériques en utilisant SAGE pour confirmer heuristiquement la conjecture de Greenberg sur la p-rationalité affirmant l'existence de corps de nombres "p-rationnels" ayant des groupes de Galois (Z/2Z)^t. Les corps p-rationnels sont des corps de nombres algébriques dont la cohomologie galoisienne est particulièrement simple. Ils sont utilisés pour construire des représentations galoisiennes ayant des images ouvertes. En généralisant le travail de Greenberg, nous construisons de nouvelles représentations galoisiennes du groupe de Galois absolu de Q ayant des images ouvertes dans des groupes réductifs sur Z_p (ex GL (n, Z_p), SL (n, Z_p ), SO (n, Z_p), Sp (2n, Z_p)). Nous prouvons des résultats qui montrent l'existence d'extensions de Lie p-adiques de Q où le groupe de Galois correspond à une certaine algèbre de Lie p-adique (par exemple sl(n), so(n), sp(2n)). Cela répond au problème classique de Galois inverse pour l'algèbre de Lie simple p-adique. / A key tool in p-adic representation theory is the Iwasawa algebra, originally constructed by Iwasawa in 1960's to study the class groups of number fields. Since then, it appeared in varied settings such as Lazard's work on p-adic Lie groups and Fontaine's work on local Galois representations. For a prime p, the Iwasawa algebra of a p-adic Lie group G, is a non-commutative completed group algebra of G which is also the algebra of p-adic measures on G. It is a general principle that objects coming from semi-simple, simply connected (split) groups have explicit presentations like Serre's presentation of semi-simple algebras and Steinberg's presentation of Chevalley groups as noticed by Clozel. In Part I, we lay the foundation by giving an explicit description of certain Iwasawa algebras. We first find an explicit presentation (by generators and relations) of the Iwasawa algebra for the principal congruence subgroup of any semi-simple, simply connected Chevalley group over Z_p. Furthermore, we extend the method to give a set of generators and relations for the Iwasawa algebra of the pro-p Iwahori subgroup of GL(n,Z_p). The base change map between the Iwasawa algebras over an extension of Q_p motivates us to study the globally analytic p-adic representations following Emerton's work. We also provide results concerning the globally analytic induced principal series representation under the action of the pro-p Iwahori subgroup of GL(n,Z_p) and determine its condition of irreducibility. In Part II, we do numerical experiments using a computer algebra system SAGE which give heuristic support to Greenberg's p-rationality conjecture affirming the existence of "p-rational" number fields with Galois groups (Z/2Z)^t. The p-rational fields are algebraic number fields whose Galois cohomology is particularly simple and they offer ways of constructing Galois representations with big open images. We go beyond Greenberg's work and construct new Galois representations of the absolute Galois group of Q with big open images in reductive groups over Z_p (ex. GL(n, Z_p), SL(n, Z_p), SO(n, Z_p), Sp(2n, Z_p)). We are proving results which show the existence of p-adic Lie extensions of Q where the Galois group corresponds to a certain specific p-adic Lie algebra (ex. sl(n), so(n), sp(2n)). This relates our work with a more general and classical inverse Galois problem for p-adic Lie extensions.

In this thesis, structures defined via modular operads and properads are generalized to their non-commutative analogs. We define the connected sum for modular operads. This way we are able to construct the graded commutative product on the algebra over Feynman transform of the modular operad. This forms a Batalin-Vilkovisky algebra with symmetry given by the modular operad. We transfer this structure to the cohomology via the Homological perturbation lemma. In particular, we consider these constructions for Quantum closed and Quantum open modular operad. As a parallel project we introduce associative analog of Frobenius properad, called Open Frobenius properad. We construct the cobar complex over it and in the spirit of Barannikov interpret algebras over cobar complex as homological differential operators. Furthermore we present the IBA∞-algebras as analog of well-known IBL∞-algebras. 1

Operators which map subsets of a given set to the set of their minimal elements with respect to some relation R form the basis of a semantic approach in non-monotonic logic, belief revision, conditional logic and updating. In this paper we investigate operators of this type from an algebraic viewpoint. A representation theorem is proved and various properties of the resulting algebras are investigated. It is shown that they behave quite differently from known algebras related to logics, e.g. modal algebras and Heyting algebras.

<p>The method of forcing is widely used in set theory to obtain&nbsp;various consistency proofs. Complete Boolean algebras play the main role&nbsp;in applications of forcing. Therefore it is useful to define games on Boolean&nbsp;algebras that characterize their properties important for the method. The&nbsp;most investigated game is Jech&rsquo;s distributivity game, such that the first&nbsp;player has the winning strategy iff the algebra is not (&omega;, 2)-distributive.&nbsp;We define another game characterizing the collapsing of the continuum to&nbsp;&omega;, prove several sufficient conditions for the second player to have a winning&nbsp;strategy, and obtain a Boolean algebra on which the game is undetermined.&nbsp;</p> / <p>Forsing je metod &scaron;iroko kori&scaron;ćen u teoriji skupova za dokaze konsistentnosti. Kompletne&nbsp; Bulove algebre igraju glavnu ulogu u primenama forsinga. Stoga je korisno definisati igre na Bulovim algebrama koje karakteri&scaron;u njihove osobine od značaja za taj metod. Najbolje proučena je Jehova igra, koja ima osobinu da prvi igrač ima pobedničku strategiju akko algebra nije (&omega;, 2)-distributivna. U tezi defini&scaron;emo jo&scaron; jednu igru, koja karakteri&scaron;e kolaps kontinuuma na &omega;, dokazujemo nekoliko dovoljnih uslova da bi drugi igra&scaron; imao pobedničku strategiju, i konstrui&scaron;emo Bulovu algebru na kojoj je igra neodređena.</p>

<p>A priori limit operator&gt;. maps sequence of a set X into a subset of X.<br />There exists maximal topology on X such that for each sequence x there holds<br />&gt;.(x) C limx. The space obtained in such way is always sequential.<br />If a priori limit operator each sequence x which satisfy lim sup x = lim inf x<br />maps into {lim sup x}, then we obtain the sequential topology Ts.&nbsp; If a priori &#39;limit<br />operator maps each sequence x into {lim sup x}, we obtain topology denoted by<br />aT. Properties of these topologies, in general, on class of Boolean algebras with<br />condition (Ii) and on class of weakly-distributive b-cc algebras are investigated.<br />Also, the relations between these classes and other classes of Boolean algebras are<br />considered.</p> / <p>A priori limit operator A svakom nizu elemenata skupa X dodeljuje neki<br />podskup skupa X. Tada na skupu X postoji maksimalna topologija takva da za<br />svaki niz x vazi A(X) c lim x. Tako dobijen prostor je uvek sekvencijalan.<br />Ako a priori limit operator svakom nizu x koji zadovoljava uslov lim sup x =<br />liminfx dodeljuje skup {limsupx} onda se, na gore opisan nacin, dobija tzv.<br />sekvencijalna topologija Ts. Ako a priori limit operator svakom nizu x dodeljuje<br />{lim sup x}, dobija se topologija oznacena sa OT.&nbsp; Ispitivane su osobine ovih<br />topologija, generalno, na klasi Bulovih algebri koje zadovoljavaju uslov (Ii) ina<br />klasi slabo-distributivnih i b-cc algebri, kao i odnosi ovih klasa prema drugim<br />klasama Bulovih algebri.</p>

The primary result from this dissertation is following inequality: d(B) ≤ min(2^< wd(B),sup{λ^c(B): λ < wd(B)}) in ZFC, where B is a homogeneous complete Boolean algebra, d(B) is the density, wd(B) is the weak density, and c(B) is the cellularity of B. Chapter II of this dissertation is a general overview of homogeneous complete Boolean algebras. Assuming the existence of a weakly inaccessible cardinal, we give an example of a homogeneous complete Boolean algebra which does not attain its cellularity. In chapter III, we prove that for any integer n > 1, wd_2(B) = wd_n(B). Also in this chapter, we show that if X⊂B is κ—weakly dense for 1 < κ < sat(B), then sup{wd_κ(B):κ < sat(B)} = d(B). In chapter IV, we address the following question: If X is weakly dense in a homogeneous complete Boolean algebra B, does there necessarily exist b € B\{0} such that {x∗b: x ∈ X} is dense in B|b = {c € B: c ≤ b}? We show that the answer is no for collapsing algebras. In chapter V, we give new proofs to some well known results concerning supporting antichains. A direct consequence of these results is the relation c(B) < wd(B), i.e., the weak density of a homogeneous complete Boolean algebra B is at least as big as the cellularity. Also in this chapter, we introduce discernible sets. We prove that a discernible set of cardinality no greater than c(B) cannot be weakly dense. In chapter VI, we prove the main result of this dissertation, i.e., d(B) ≤ min(2^< wd(B),sup{λ^c(B): λ < wd(B)}). In chapter VII, we list some unsolved problems concerning this dissertation.