Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / O objetivo principal deste trabalho à apresentar alguns resultados, relativos ao nÃmero de classes do subcorpo real maximal de um corpo ciclotÃmico.Para isso, iremos inicialmente provar a finitude do grupo das classes de ideais e fazer um breve estudo da decomposiÃÃo de ideais primos em uma extensÃo. Na sequÃncia, apresentaremos o subcorpo real maximal de um corpo ciclotÃmico e usaremos alguns resultados relativos a caracteres e somas gaussianas, para justificar a imersÃo de um corpo quadrÃtico real em um subcorpo real maximal particular. Depois disso, vamos apresentar os resultados de dois artigos, o primeiro de N. C. Ankeny, S. Chowla E H. Hasse, e o segundo de Hideo Yokoi. Ambos tem por objetivo, estudar o nÃmero de classes do subcorpo real maximal de um corpo ciclotÃmico. / The aim of this paper is to present some results on the number of classes of real maximal subcorpo a body ciclotÃmico.Para this, we will first prove the finiteness of the group of classes of ideals and make a brief study of the decomposition of prime ideals in a extension. Following, we present the real subcorpo a maximal cyclotomic fields and will use some results on the characters and Gaussian sums, to justify the dumping of a body in a real quadratic subcorpo maximal real particular. After that, we present the results of two articles, the first of N. C. Ankeny, S. Chowla and H. Hasse, and the second of Hideo Yokoi. Both have the objective of studying the number of classes of real subcorpo a maximal cyclotomic fields.

Neste trabalho, apresentamos um estudo sobre a existência ou não de bases normais auto-duais para extensões galoisianas finitas de corpos, mostrando que toda extensão galoisiana finita de grau ímpar posui uma base normal auto-dual, enquanto que para extensões galoisianas de grau par, apresentamos algumas condições suficientes que garantem a não existência de bases normais auto-duais / In this work, we present a study about the existence or not of self-dual normal bases for finite galoisian extensions of fields, showing that all the odd degree finite galoisian extension has a self-dual normal base, whereas for even degree galoisian extensions, we present some sufficient conditions that assure the non-existence of self-dual normal bases

Orientador: Antonio José Engler / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação Científica / Made available in DSpace on 2018-08-24T22:18:49Z (GMT). No. of bitstreams: 1 Matos_FabioAlexandrede_D.pdf: 1117786 bytes, checksum: ce8cedb8cf95de8f81d4d520e2d308ad (MD5) Previous issue date: 2014 / Resumo: Apresentaremos neste trabalho um estudo sobre a aritmética corpos de característica distinta de 2 com um número finito de classes de quadrados. Dividido em duas partes, começaremos com um estudo do radical de Kaplansky de um corpo F e seu comportamento em 2-extensões de F. Na segunda parte introduziremos um novo objeto, as bases distinguidas, e exploraremos suas propriedades obtendo uma generalização do Teorema 90 de Hilbert, versão para o radical de Kaplansky, e propriedades cohomológicas de corpos que possuam base distinguida / Abstract: We will present in this work a study about the arithmetic of fields of characteristic different from 2 with a finite number of square class. Divided in two parts, we will start with a study of the Kaplansky¿s radical of a field F and its behavior in 2-extensions of F. In the second part will introduce a new object, the distinguished bases, and we will explore its properties obtaining a generalization of Hilbert¿s Theorem 90 for the Kaplansky's radical and cohomological properties of fields that own distinguished basis / Doutorado / Matematica / Doutor em Matemática

No description available.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24392号 / 理博第4891号 / 新制||理||1699(附属図書館) / 京都大学大学院理学研究科数学・数理解析専攻 / (主査)教授 玉川 安騎男, 教授 並河 良典, 教授 望月 新一 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Seja p um primo, considere q = pe com e ≥ 1 inteiro. Dado o polinômio f (x) = x4+ax3+bx2+ cx+d ∈ Fq[x], consideremos o polinômio F(T) = T4 +aT3 +bT2 +cT + d - y ∈ Fq(y)[T], com y = f (x) sobre Fq(y). O objetivo desse trabalho é determinar o número de polinômios f (x) que tem seu grupo de galois associado GF isomorfo a cada subgrupo transitivo (prefixado) de S4. O trabalho foi baseado no artigo: Galois closures of quartic sub-fields of rational function fields, usando equações auxiliares associadas ao polinômio minimal F(T) de graus 3 e 2 (DUMMIT, 1994); bem como uma caraterização das curvas projetivas planas de grau 2 não singulares. Se car(k) ≠ 2, associamos a F(T) sua cúbica resolvente RF(T) e seu discriminante ΔF. Em seguida obtemos condições para GF ≅ C4 (vide Teorema 2.9), que é ocaso fundamental para determinação dos demais casos. Se car(k) = 2, procuramos determinar condições para GRF ≅ A3, associando ao polinômio RF(T) sua quadrática resolvente P(T) (vide a Proposição 2.13). Apos ter homogeneizado P(T), usamos uma das consequências do teorema de Bézout, a saber, uma curva algébrica projetiva plana C de grau 2 é irredutível se, e somente se, C não tem pontos singulares. Nesta dissertação obtemos resultados semelhantes com uma abordagem relativamente diferente daquela usada pelo autor R. Valentini. / Let be p a prime, q = pe whit e ≥ 1 integer. Let a polynomial f (x) = x4+ax3+bx2+cx+d ∈ Fq[x], considering the polynomial F(T)=T4+aT3+bT2+cT +d, with y= f (x) over Fq(y)[T]. The purpose of the current research is to determine the numbers of polynomials f (x) which have its associated Galois group GF, this GF is isomorphic for each transitive subgroup (prefixed) of A4. This project is based on the article: Galois closures of quartic sub-fields of rational function fields, using auxiliary equations associated to the minimal polynomial F(T) of degrees 3 and 2 (DUMMIT, 1994); besides a characterization of non-singular projective plane curves of degree 2 was used. If car(k) ≠ 2, associated to F(T) the resolvent cubic RF(T) and its discriminant ΔF then conditions for GF are obtained as GF ≅ C4 which is the fundamental case for determining the other cases (Theorem 2.9). If car(k) = 2, to find conditions for GRF ≅ A3, associated to the polynomial RF(T) its resolvent quadratic p(T) (Proposition 2.13). Homogenizing p(T), one of the consequences of the Bezout theorem was applied. It is, a projective plane curve C, which grade 2, is irreducible if and only if C is smooth. In the current dissertation, similar results were obtained using a different approach developed by the author R. Valentini.

Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2009. / Includes bibliographical references.

Seja p um primo, considere q = pe com e ≥ 1 inteiro. Dado o polinômio f (x) = x4+ax3+bx2+ cx+d ∈ Fq[x], consideremos o polinômio F(T) = T4 +aT3 +bT2 +cT + d - y ∈ Fq(y)[T], com y = f (x) sobre Fq(y). O objetivo desse trabalho é determinar o número de polinômios f (x) que tem seu grupo de galois associado GF isomorfo a cada subgrupo transitivo (prefixado) de S4. O trabalho foi baseado no artigo: Galois closures of quartic sub-fields of rational function fields, usando equações auxiliares associadas ao polinômio minimal F(T) de graus 3 e 2 (DUMMIT, 1994); bem como uma caraterização das curvas projetivas planas de grau 2 não singulares. Se car(k) ≠ 2, associamos a F(T) sua cúbica resolvente RF(T) e seu discriminante ΔF. Em seguida obtemos condições para GF ≅ C4 (vide Teorema 2.9), que é ocaso fundamental para determinação dos demais casos. Se car(k) = 2, procuramos determinar condições para GRF ≅ A3, associando ao polinômio RF(T) sua quadrática resolvente P(T) (vide a Proposição 2.13). Apos ter homogeneizado P(T), usamos uma das consequências do teorema de Bézout, a saber, uma curva algébrica projetiva plana C de grau 2 é irredutível se, e somente se, C não tem pontos singulares. Nesta dissertação obtemos resultados semelhantes com uma abordagem relativamente diferente daquela usada pelo autor R. Valentini. / Let be p a prime, q = pe whit e ≥ 1 integer. Let a polynomial f (x) = x4+ax3+bx2+cx+d ∈ Fq[x], considering the polynomial F(T)=T4+aT3+bT2+cT +d, with y= f (x) over Fq(y)[T]. The purpose of the current research is to determine the numbers of polynomials f (x) which have its associated Galois group GF, this GF is isomorphic for each transitive subgroup (prefixed) of A4. This project is based on the article: Galois closures of quartic sub-fields of rational function fields, using auxiliary equations associated to the minimal polynomial F(T) of degrees 3 and 2 (DUMMIT, 1994); besides a characterization of non-singular projective plane curves of degree 2 was used. If car(k) ≠ 2, associated to F(T) the resolvent cubic RF(T) and its discriminant ΔF then conditions for GF are obtained as GF ≅ C4 which is the fundamental case for determining the other cases (Theorem 2.9). If car(k) = 2, to find conditions for GRF ≅ A3, associated to the polynomial RF(T) its resolvent quadratic p(T) (Proposition 2.13). Homogenizing p(T), one of the consequences of the Bezout theorem was applied. It is, a projective plane curve C, which grade 2, is irreducible if and only if C is smooth. In the current dissertation, similar results were obtained using a different approach developed by the author R. Valentini.

Le pseudo-groupe de Malgrange d'un champ de vecteurs défini sur une variété est la sous-pro-variété de l'espace des jets de biholomorphismes locaux de cette variété obtenue en prenant la clôture de Zariski des flots du champ de vecteurs. Une équation différentielle ordinaire d'ordre 2 définit un champ de vecteurs sur une variété de dimension 3. Le pseudogroupe de Malgrange de ce dernier est de type différentiel d'ordre inférieur ou égal à 2. Une équation différentielle ordinaire d'ordre 2 est dite irréductible si ses solutions générales ne peuvent pas être exprimées à l'aide de solutions d'équations algébriques, différentielles linéaires ou différentielles d'ordre 1. Si le type différentiel du pseudo-groupe de Malgrange d'une équation d'ordre 2 est exactement 2 alors cette dernière est irréductible. Nous donnons plusieurs définitions du pseudo-groupe de Malgrange d'un champ de vecteurs équivalentes à la définition originale donnée par Bernard Malgrange. La définition du premier paragraphe nous permet d'appliquer un théorème de semi-continuité de la dimension des clôtures de Zariski des feuilles d'un feuilletage holomorphe de Philippe Bonnet. Nous obtenons le résultat suivant concernant les équations différentielles ordinaires dépendant de paramètres. Si le type différentiel du pseudo-groupe de Malgrange de l'équation spécialisée en une valeur des paramètres est à exactement 2 alors il en sera de même pour les pseudo-groupes de Malgrange de l'équation spécialisée en des valeurs générales des paramètres. Une première application de ce résultat est de redémontrer l'irréductibilité des équations de Painlevé pour des valeurs générales des paramètres. Une seconde application est de déterminer complètement les pseudo-groupes de Malgrange de ces équations pour des valeurs générales des paramètres. Les définitions du pseudo-groupe de Malgrange et les résultats de spécialisations s'adaptent aux équations aux q-différences. En appliquant ces résultats aux équations de Painlevé discrètes, nous obtenons le pseudo-groupe de Malgrange de ces dernières pour des valeurs générales des paramètres. / The Malgrange pseudogroup of a vector field on a variety is the sub-pro-variety of the jet space of local biholomorphisms of this variety obtained by taking the Zariski closure of the flow of the vector field. A second-order ordinary differential equation defines a vector field on a variety of dimension 3. The differential type of the Malgrange pseudogroup of this one is at most 2. A second-order ordinary differential equation is said to be irreductible if its general solutions can not be expressed using solutions of algebraic equations, linear differential equations or differential equations of order 1. If the differential type of the Malgrange pseudogroup of a second-order differential equation is exactly 2 then the latter is irreductible. We give several definitions of the Malgrange pseudogroup of a vector field which are equivalent to the original definition given by Bernard Malgrange. The definition of the first paragraph leads us to apply a semi-continuity theorem of the dimension of the Zariski closure of the leaves of a holomorphic foliation given by Philippe Bonnet. We obtain the following result about the ordinary differential equations which depend on parameters. If the differential type of the Malgrange pseudogroup of the equation specialized in one value of parameters is exactly two then it will be the same for the Malgrange pseudogroup of the equation specialized in a general value of parameters. A first application of this result is an other proof of the irreductibility of the Painlevé equations for general value of parameters. A second application is to fully determined the Malgrange pseudogroups of this equations for general value of parameters. The definitions of the Malgrange pseudogroup of a vector field and the specialisation results can be adapted the q-difference equations. By applying this results to the discret Painlevé equations, we fully determined the Malgrange pseudogroup of the latters for general value of parameters.

This report studies polynomial equations and how one solves them using only the coefficients of the polynomial. It examines why it is impossible to solve equations of degree greater than four using only radicals and how instead one can solve them using elliptic functions. Although the quintic equation is the main area of our investigation, we also present parts of the history of algebraic equations, Galois theory, and elliptic functions.