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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Construções genéricas de espaços de Asplund C(K) / Generic constructions of Asplund spaces C(K)

Christina Brech 29 April 2008 (has links)
Neste trabalho consideramos um método de construções genéricas de espaços compactos e dispersos não-metrizáveis, desenvolvido por Baumgartner, Shelah, Rabus, Juhasz e Soukup. Introduzimos novas técnicas e obtemos novas aplicações relevantes tanto para a topologia dos espaços compactos quanto para a geometria dos espaços de Banach de funções contínuas. As novas técnicas dizem respeito a novas amalgamações de condições do forcing que adiciona os espaços dispersos, bem como a generalizações dos argumentos dos autores acima citados de pontos de um espaço compacto K para medidas de Radon sobre K. Como aplicações, obtemos dois novos espaços compactos e dispersos K_1 e K_2, com as propriedades abaixo. K_1 é um espaço hereditariamente separável de peso aleph_1 tal que C(K_1) possui a propriedade (C) de Corson e não possui a propriedade (E) de Efremov. K_2 é o primeiro exemplo de um espaço compacto disperso, hereditariamente separável, de altura omega_2. Segue que o grau de Lindelöf hereditário de K_2 é aleph_2, mostrando a consistência de que hL(K) é estritamente maior que o sucessor de hd(K) para espaços compactos K. C(K_2) é o primeiro exemplo consistente de um espaço de densidade aleph_2 que não possui um sistema biortogonal não-enumerável. / In this work we consider a method of generic constructions of compact scattered non-metrizable spaces developed by Baumgartner, Shelah, Rabus, Juhasz and Soukup. We introduce new techniques and obtain new applications both relevant to topology of compact spaces and the geometry of Banach spaces of continuous functions. The new techniques concern new amalgamations of conditions of forcing which add the dispersed spaces as well as the generalizations of arguments of the above-mentioned authors from points of a compact space K to Radon measures on K. As applications we obtain two compact scattered spaces K_1 and K_2 with the properties below. K_1 is a hereditarily separable space of weight aleph_1 such that C(K_1) has property (C) of Corson and does not have property (E) of Efremov. K_2 is the first (consistent) example of a compact scattered space which is hereditarily separable and whose height is omega_2. It follows that its hereditary Lindelöf degree is aleph_2, showing the consistency of hL(K) can me strictly greater than the successor of hd(K) for compact spaces K. C(K_2) is the first consistent example of a Banach space of density aleph_2 without uncountable biorthogonal systems.
22

Sobre operadores entre espaços de sequências que atingem a norma

Silva, Juan Carlo da Cruz 02 December 2009 (has links)
Made available in DSpace on 2015-05-15T11:46:15Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 346206 bytes, checksum: 8088f6a0baa8eb637021343c390a391a (MD5) Previous issue date: 2009-12-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this work we present a recent result, due to D. Pellegrino and E. V. Teixeira, that characterizes the continuous linear operators between lpspaces which attain their norms. To this end, we Örstly explore some topics from the Banach space theory, such as Banachís Theorem for basis, Bessaga-Pe ̃czynski Selection Principle and Pittís Theorem. / Neste trabalho apresentaremos um recente resultado, devido a D. Pellegrino e E. V. Teixeira, que caracteriza os operadores lineares contínuos entre espaços lp que atingem a norma. Para tanto, vamos desenvolver alguns tópicos da teoria de bases em espaços de Banach e também mostrar alguns importantes resultados da teoria de espaços de Banach, tais como o Teorema de Banach sobre bases, o Princípio de Seleção de Bessaga- Pe÷czy´nski e o Teorema de Pitt.
23

Biortogonalių orbitalių metodo plėtojimas ir taikymas atomo teorijoje / Development of biorthogonal orbital method and its application in atomic physics

Rynkun, Pavel 16 June 2014 (has links)
Disertacijos tikslai: išplėtoti biortogonalių orbitalių metodą energijų ir kitų svarbių atominių charakteristikų skaičiavimui; gauti tikslesnes atomines charakteristikas (energijos lygmenis, šuolių tikimybes, lygmenų gyvavimo trukmes) ab initio metodu. Disertacija sudaryta iš šešių skyrių. Pirmas skyrius yra įvadinis. Jame pristatomi disertacijos tikslai, uždaviniai ir ginamieji teiginiai. Antras skyrius skirtas disertacijoje naudojamiems ir kuriamiems teoriniams metodams aprašyti. Jame aprašomas naujai sukurtas PCFI artinys paremtas biortogonaliomis transformacijomis ir aprašomi, kokie pakeitimai buvo padaryti Breito ir Paulio operatorių matricinių elementų išraiškose, atsižvelgiant į biortogonalių orbitalių metodo specifiką. Kiti trys skyriai skirti disertacijoje gautiems rezultatams pristatyti. Kiekviename iš jų pateikiama mokslinių tyrimų apžvalga ir svarba. Trečiame skyriuje pateikiami apskaičiuoti spektroskopiniai duomenys boro, anglies, azoto ir deguonies izoelektronėms sekoms. Ketvirtame skyriuje pateikiami W24+ jono energijos lygmenys, stipriausi elektriniai dipoliniai šuoliai, gyvavimo trukmės. Penktame skyriuje pateikiami suskirstytų koreliacinių funkcijų sąveikos metodo taikymai ličio ir boro atomams. Neutralaus boro šuolio energijos tarp 2Po - 4P termų skaičiavimai atlikti naudojantis MCHF bei PCFI metodais. Paskutiniame skyriuje pateikiamos disertacijos išvados. / The main goals of the study are: to develop the biorthogonal orbital method for calculation of energies and other important atomic data; to obtain more accurate atomic data (energy levels, transition rates, and lifetimes) using ab initio method. The doctoral dissertation consists of six chapters. Chapter 1 introduces the main goals, main tasks of the study and statements presented for defence. Chapter 2 is designed to describe theoretical methods that were used in the thesis. There is also an account of the newly developed PCFI method based on biorthogonal transformations and the modifications in spin-angular part that were needed. The other three chapters are devoted to presenting the results obtained in the dissertation. Each of them has a scientific review of the research and importance. Also the results obtained in this work are compared with other authors’ theoretical and experimental data. Chapter 3 presents the calculation of spectroscopic data of boron, carbon, nitrogen and oxygen isoelectronic sequences. Chapter 4 presents the results of the W24+ calculations: energy spectra structure, the strongest electric dipole transitions, and the lifetimes. In Chapter 5 applications of PCFI approach are presented for lithium and boron. For neutral boron the 2Po and 4P transition energy was calculated using MCHF and PCFI methods. Chapter 6 presents the conclusions of the study.
24

Development of biorthogonal orbital method and its application in atomic physics / Biortogonalių orbitalių metodo plėtojimas ir taikymas atomo teorijoje

Rynkun, Pavel 16 June 2014 (has links)
The main goals of the study are: to develop the biorthogonal orbital method for calculation of energies and other important atomic data; to obtain more accurate atomic data (energy levels, transition rates, and lifetimes) using ab initio method. The doctoral dissertation consists of six chapters. Chapter 1 introduces the main goals, main tasks of the study and statements presented for defence. Chapter 2 is designed to describe theoretical methods that were used in the thesis. There is also an account of the newly developed PCFI method based on biorthogonal transformations and the modifications in spin-angular part that were needed. The other three chapters are devoted to presenting the results obtained in the dissertation. Each of them has a scientific review of the research and importance. Also the results obtained in this work are compared with other authors’ theoretical and experimental data. Chapter 3 presents the calculation of spectroscopic data of boron, carbon, nitrogen and oxygen isoelectronic sequences. Chapter 4 presents the results of the W(24+) calculations: energy spectra structure, the strongest electric dipole transitions, and the lifetimes. In Chapter 5 applications of PCFI approach are presented for lithium and boron. For neutral boron the 2Po and 4P transition energy was calculated using MCHF and PCFI methods. Chapter 6 presents the conclusions of the study. / Disertacijos tikslai: išplėtoti biortogonalių orbitalių metodą energijų ir kitų svarbių atominių charakteristikų skaičiavimui; gauti tikslesnes atomines charakteristikas (energijos lygmenis, šuolių tikimybes, lygmenų gyvavimo trukmes) ab initio metodu. Disertacija sudaryta iš šešių skyrių. Pirmas skyrius yra įvadinis. Jame pristatomi disertacijos tikslai, uždaviniai ir ginamieji teiginiai. Antras skyrius skirtas disertacijoje naudojamiems ir kuriamiems teoriniams metodams aprašyti. Jame aprašomas naujai sukurtas PCFI artinys paremtas biortogonaliomis transformacijomis ir aprašomi, kokie pakeitimai buvo padaryti Breito ir Paulio operatorių matricinių elementų išraiškose, atsižvelgiant į biortogonalių orbitalių metodo specifiką. Kiti trys skyriai skirti disertacijoje gautiems rezultatams pristatyti. Kiekviename iš jų pateikiama mokslinių tyrimų apžvalga ir svarba. Trečiame skyriuje pateikiami apskaičiuoti spektroskopiniai duomenys boro, anglies, azoto ir deguonies izoelektronėms sekoms. Ketvirtame skyriuje pateikiami W(24+) jono energijos lygmenys, stipriausi elektriniai dipoliniai šuoliai, gyvavimo trukmės. Penktame skyriuje pateikiami suskirstytų koreliacinių funkcijų sąveikos metodo taikymai ličio ir boro atomams. Neutralaus boro šuolio energijos tarp 2Po - 4P termų skaičiavimai atlikti naudojantis MCHF bei PCFI metodais. Paskutiniame skyriuje pateikiamos disertacijos išvados.
25

Compacta in Banach spaces

González Correa, Alma Lucía 24 May 2010 (has links)
Capítulo 1. Después de estudiar algunos preliminares sobre familias adecuadas de conjuntos, formulamos y probamos algunas equivalencias, cada una de ellas son una condición suficiente para que la familia defina un conjunto compacto de Gul'ko. Damos una caracterización de conjunto compacto de Gul'ko en términos de emparejamiento con un conjunto $\mathcal{K}$-analítico. Capítulo 2. Estudiamos propiedades de los espacios de Banach débilmente Lindelöf determinados no-separables. Damos una caracterización por medio de la existencia de un generador proyeccional full sobre él. Estudiamos algunos aspectos sobre sistemas biortogonales en espacios de Banach. Usando técnicas de resoluciones proyeccionales de la identidad, probamos una extensión de un resultado de Argyros y Mercourakis. Capítulo 3. En el espacio $(c_0(\Gamma),\|\cdot\|_\infty)$, con $\Gamma\in\mathbb{R}$, damos una norma equivalente estrictamente convexa. Capítulo 4. Consideramos una caracterización de los subespacios de espacios de Banach débilmente compactamente generados, en términos de una propiedad de cubrimiento de la bola unidad por medio de conjuntos $\epsilon$-débilmente compactos. Reemplazamos este concepto por otro más preciso que llamamos $\epsilon$-débilmente auto-compactos, este concepto permite una mejor descripción. Capítulo 5. Damos condiciones intrínsecas, necesarias y suficientes para que un espacio de Banach sea generado por $c_0(\Gamma)$ o $\ell_p(\Gamma)$ para $p\in(1,+\infty)$. Ofrecemos una nueva demostración de un resultado de Rosenthal, sobre operadores de $c_0(\Gamma)$ en un espacio de Banach. / González Correa, AL. (2008). Compacta in Banach spaces [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8312
26

Algèbre d'Askey–Wilson, centralisateurs et fonctions spéciales (bi)orthogonales

Zaimi, Meri 06 1900 (has links)
Cette thèse est divisée en quatre parties qui portent sur les centralisateurs des algèbres quantiques \(U_q(\mathfrak{sl}_N)\), les polynômes biorthogonaux avec propriétés bispectrales, les polynômes bivariés de Griffiths, et les schémas d'association avec structures polynomiales bivariées. Le fil conducteur principal entre ces parties est l'algèbre d'Askey–Wilson. Dans la première partie, l'idée principale est de combiner l'algèbre du groupe des tresses avec l'algèbre d'Askey–Wilson dans des situations qui impliquent les centralisateurs de \(U_q(\mathfrak{sl}_2)\). Ainsi, on obtient des représentations du groupe des tresses en termes de polynômes orthogonaux de \(q\)-Racah par le biais de matrices \(R\) de \(U_q(\mathfrak{sl}_2)\), on obtient une interprétation de l'algèbre d'Askey–Wilson dans le cadre de la théorie topologique des champs de Chern–Simons avec groupe de jauge \(SU(2)\) ainsi que dans le cadre des invariants d'entrelacs associés à \(U_q(\mathfrak{su}_2)\), et on offre une description algébrique complète du centralisateur de \(U_q(\mathfrak{sl}_2)\) dans un produit tensoriel de trois représentations irréductibles identiques de spin quelconque. Dans une optique différente, on offre aussi une présentation algébrique de certaines algèbres de Hecke fusionnées qui décrivent des centralisateurs de \(U_q(\mathfrak{sl}_N)\). Dans la deuxième partie, on étudie deux familles de polynômes biorthogonaux par des méthodes algébriques, offrant une extension du tableau qui existe pour les polynômes orthogonaux classiques de type Askey–Wilson. Les deux familles considérées sont les polynômes \(R_I\) de type Hahn et les polynômes de Pastro. Dans les deux cas, l'idée est d'introduire un triplet d'opérateurs ayant une action tridiagonale et d'obtenir les polynômes comme solutions à deux problèmes aux valeurs propres généralisés provenant de ce triplet. On trouve les propriétés de bispectralité et de biorthogonalité des polynômes en se servant des opérateurs du triplet, et on détermine l'algèbre réalisée par les opérateurs. Dans la troisième partie, on caractérise deux familles de polynômes bivariés de Griffiths. La première famille est une généralisation des polynômes de Griffiths de type Krawtchouk qui dépend d'un paramètre \(\lambda\). On trouve leurs relations de bispectralité et leur biorthogonalité en utilisant les propriétés des polynômes de Krawtchouk à une variable. Les relations de contiguïté des polynômes univariés jouent un rôle essentiel dans les calculs. On utilise des méthodes semblables pour caractériser la deuxième famille, qui est formée de polynômes de Griffiths de type Racah. Ceux-ci sont orthogonaux. Dans la quatrième partie, on propose une généralisation bivariée des propriétés \(P\)- et \(Q\)-polynomiales pour les schémas d'association et de concepts reliés. Plusieurs exemples de schémas vérifiant la propriété \(P\)-polynomiale bivariée sont obtenus. On montre que les schémas de Johnson non-binaires ainsi que leurs analogues \(q\)-déformés, les schémas définis à partir d'espaces atténués, sont \(P\)- et \(Q\)-polynomiaux bivariés en étudiant les propriétés bispectrales des polynômes bivariés associés. Les structures algébriques reliées à ces schémas sont explorées. On propose aussi une généralisation multivariée des graphes distance-réguliers, et on montre que ceux-ci sont en correspondance avec des schémas \(P\)-polynomiaux multivariés. Finalement, on étudie une sous-classe de paires de Leonard de rang 2 qui font intervenir des polynômes bivariés factorisés. / This thesis is divided in four parts concerning centralizers of quantum algebras \(U_q(\mathfrak{sl}_N)\), biorthogonal polynomials with bispectral properties, bivariate Griffiths polynomials, and association schemes with bivariate polynomial structures. The main topic relating all these parts is the Askey–Wilson algebra. In the first part, the main idea is to combine the braid group algebra with the Askey–Wilson algebra in situations involving the centralizers of the quantum algebra \(U_q(\mathfrak{sl}_2)\). Hence, we obtain representations of the braid group in terms of \(q\)-Racah orthogonal polynomials using \(R\)-matrices of \(U_q(\mathfrak{sl}_2)\), we obtain an interpretation of the Askey–Wilson algebra in the framework of Chern–Simons topological quantum field theory with gauge field \(SU(2)\) as well as in the framework of link invariants associated to \(U_q(\mathfrak{su}_2)\), and we provide a complete algebraic description of the centralizer of \(U_q(\mathfrak{sl}_2)\) in the tensor product of three identical irreducible representations of any spin. In a different perspective, we also provide an algebraic presentation of some fused Hecke algebras, which describe some centralizers of \(U_q(\mathfrak{sl}_N)\). In the second part, we study two families of biorthogonal polynomials using algebraic methods, hence extending the picture that exists for the classical orthogonal polynomials of the Askey–Wilson type. The two families that we consider are the \(R_I\) polynomials of Hahn type and the Pastro polynomials. In both cases, the idea is to introduce a triplet of operators with tridiagonal actions and obtain the polynomials as solutions of two generalized eigenvalue problems involving this triplet. We find the bispectrality and biorthogonality properties of the polynomials using the operators of the triplet, and we determine the algebra realized by the operators. In the third part, we characterize two families of bivariate Griffiths polynomials. The first family is a generalization of the Griffiths polynomials of Krawtchouk type which depends on a parameter \(\lambda\). We find their bispectrality relations and their biorthogonality by using the properties of univariate Krawtchouk polynomials. The contiguity relations of the univariate polynomials play a key role in the computations. We use similar methods to characterize the second family, which is formed by Griffiths polynomials of Racah type. These are orthogonal. In the fourth part, we propose a bivariate generalization of the \(P\)- and \(Q\)-polynomial properties of association schemes and related concepts. Several examples of schemes satisfying the bivariate \(P\)-polynomial property are obtained. We show that the non-binary Johnson schemes and their \(q\)-deformed analogs, the schemes based on attenuated spaces, are bivariate \(P\)- and \(Q\)-polynomial by studying the bispectral properties of the associated bivariate polynomials. The algebraic structures related to these schemes are explored. We also propose a multivariate generalization of distance-regular graphs, and we show that these are in correspondence with multivariate \(P\)-polynomial schemes. Finally, we study a subclass of rank 2 Leonard pairs involving factorized bivariate polynomials.

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