Dissertations / Theses on the topic 'Polynomials in Banach spaces'

Orientador: Jorge Tulio Mujica Ascui
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica
Made available in DSpace on 2018-08-08T04:55:28Z (GMT). No. of bitstreams: 1 BerriosYana_SoniaSarita_D.pdf: 951582 bytes, checksum: eb4f2207b2bb049f8b5c1e264d96ec85 (MD5) Previous issue date: 2007
Resumo: Sejam E e F espaços de Banach complexos, e seja U um aberto em E. Neste trabalho estudamos os subespaços Hwu(U; F), Hw(U; F), Hwsc(U; F) e HwC(U; F) de H(U; F). Mais especificamente, se U é aberto equilibrado caracterizamos funções destes subespaços em termos de condições de equicontinuidade dos polinômios da série de Taylor. Estudamos sob que condições estes subespaços coincidem, estendendo assim os resultados dados em Aron, Herves e Valdivia [2] ao caso de abertos equilibrados. Se E tem uma base contrátil e incondicional, e U é uma bola aberta em E mostramos que cada função holomorfa f : U 'seta' F que é limitada nos conjuntos fracamente compactos U-limitados é limitada nos conjuntos U-limitados. Consequentemente, Hw(U; F) = Hwu(U; F)
Abstract: Let E and F be complex Banach spaces, and let U be an open set in E. In this work we study the subspaces Hwu(U; F), Hw(U; F), Hwsc(U; F) and HwC(U; F) of H(U; F). More specifically, if U is a balanced open set we characterize functions of these subespaces in terms of equicontinuity conditions of the polynomials in the Taylor series. We study under which conditions these subspaces coincide, and then we extend the results given in Aron, Herves and Valdivia [2] to the case of balanced open sets. If E has a shrinking and unconditional basis, and U is an open ball in E we show that each holomorphic function f : U 'seta' F that is bounded on weakly compact U-bounded sets is bounded on U-bounded sets. Consequently, Hw(U; F) = Hwu(U; F)
Doutorado
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

Esta dissertação tem por objetivo a apresentação de um estudo em espaços de Banach sobre os conjuntos nos quais determinados polinômios homogêneos contínuos são fracamente sequencialmente contínuos. Algumas propriedades desses conjuntos são estudadas e ilustradas com exemplos, em maior parte no espaço $l_p$. Obtemos um fórmula para o conjunto de continuidade sequencial fraca do produto de dois polinômios e algumas consequências. Resultados mais fortes são obtidos quando restringimos nossos espaços de Banach a espaços com FDD incondicional e/ou separáveis. Os resultados estudados aqui foram obtidos por R. Aron e V. Dimant em: Aron, R. & Dimant, V., Sets of weak sequential continuity for polynomials, Indag. Mathem., N.S., 13 (3) (2002), 287-299.
This work has the purpose of presenting a study on Banach spaces about sets in which determined homogeneous continuous polynomials are weakly sequentially continuous. Some properties of these sets are studied and illustrated with examples, most in the space $l_p$. We obtain a formula for the weak sequential continuity set of the product of two polynomials, and some consequences. Stronger results are obtained when we restrict our Banach spaces to spaces with unconditional FDD and/or separable. The results studied here were obtained by R. Aron and V. Dimant in: Aron, R. & Dimant, V., {Sets of weak sequential continuity for polynomials, Indag. Mathem., N.S., 13 (3) (2002), 287-299.

Orientador: Jorge Tulio Mujica Ascui
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica
Made available in DSpace on 2018-08-08T22:02:35Z (GMT). No. of bitstreams: 1 Kuo_PoLing_D.pdf: 378648 bytes, checksum: 3724407371cc36985fd2257b4bc5fe8c (MD5) Previous issue date: 2007
Resumo: Este trabalho está dedicado ao estudo dos operadores de Nicodemi, introduzidos em [7] a partir de uma idéia em [12]. Os operadores de Nicodemi levam aplicações multilineares (resp. polinômios homogêneos) de um espaço de Banach E em aplicações multilineares (resp. polinômios homogêneos) em um espaço de Banach F. O nosso primeiro objetivo é encontrar condições para que os operadores de Nicodemi preservem certos tipos de aplicações multilineares (resp. polinômios homogêneos). Em particular estudamos a preservação de aplicações multilineares simétricas, de tipo finito, nucleares, compactas ou fracamente compactas. O segundo objetivo é encontrar condições para que, se os espaços duais E¿ e F¿ são isomorfos, os espaços de aplicações multilineares (resp. polinômios homogêneos) em E e F sejam isomorfos também. Estudamos também o problema correspondente para os espaços de aplicações multilineares (resp. polinômios homogêneos) de um determinado tipo, como por exemplo, de tipo finito, nuclear, compacto ou fracamente compacto
Abstract: This work is devoted to studying the Nicodemi operators, introduced in [7], following an idea in [12]. The Nicodemi operators map multilinear mappings (resp. homogeneous polynomials) on a Banach spaces E into multilinear mappings (resp. homogeneous polynomials) on a Banach spaces F. Our first objective is to find conditions under which the Nicodemi operators preserve certain types of multilinear mappings (resp. homogeneous polynomials). In particular we examine the preservation of the multilinear mappings that are symmetric, of finite type, nuclear, compact or weakly compact. Our second objective is tofind conditions under which, whenever the dual spaces E¿ and F¿ are isomorphic, the spaces of multilinear mappings (resp. homogeneous polynomials) on E and F are isomorphic as well. We also examine the corresponding problem for the spaces of multilinear mappings (resp. homogeneous polynomials) of a certain type, for instance of finite, nuclear, compact or weakly compact type
Doutorado
Analise Funcional
Doutor em Matemática

Nesse trabalho introduzimos e desenvolvemos a teoria de hiper-ideais de aplicações multilineares contínuas e polinômios homogêneos contínuos entre espaços de Banach. A ideia central é refinar os conceitos de multi-ideais e de ideais de polinômios com o objetivo de explorar de forma mais aprofundada a natureza não-linear das aplicações envolvidas. Para isso tomamos a teoria de ideais de operadores lineares, aplicações multilineares e polinômios homogêneos, desenvolvida a partir dos trabalhos de Pietsch, tanto no caso linear como no caso multilinear, como referencial. Provamos resultados gerais para hiper-ideais, damos muitos exemplos ilustrativos, e desenvolvemos métodos para gerar hiper-ideais, tanto no caso multilinear como no caso polinomial.
In this work we introduce and develop the theory of hyper-ideals of multilinear mappings and homogeneous polynomials between Banach spaces. The main idea is to refine the concepts of multi-ideal and of ideal of polynomials with the purpose of exploring deeply the nonlinear nature of the underlying mappings. To do this we take the ideal theory of linear operators, multilinear mappings and homogeneous polynomials, developed from the works of Pietsch, both in the linear and nonlinear cases, as a reference. We prove general results for hyper-ideals, provide a number of illustrative examples, and develop methods to generate hyper-ideals of multilinear mappings, as well as of hyper-ideals of homogeneous polynomials.

Recall that a Banach space X has the Dunford-Pettis property if every weakly compact operator defined on X takes weakly compact sets into norm compact sets. Some valuable characterisations of Banach spaces with the Dunford-Pettis property are: X has the DPP if and only if for all Banach spaces Y, every weakly compact operator from X to Y sends weakly convergent sequences onto norm convergent sequences (i.e. it requires that weakly compact operators on X are completely continuous) and this is equivalent to “if (xn) and (x*n) are sequences in X and X* respectively and limn xn = 0 weakly and limn x*n = 0 weakly then limn x*n xn = 0". A striking application of the Dunford-Pettis property (as was observed by Grothendieck) is to prove that if X is a linear subspace of L() for some finite measure  and X is closed in some Lp() for 1 ≤ p < , then X is finite dimensional. The fact that the well known spaces L1() and C() have this property (as was proved by Dunford and Pettis) was a remarkable achievement in the early history of Banach spaces and was motivated by the study of integral equations and the hope to develop an understanding of linear operators on Lp() for p ≥ 1. In fact, it played an important role in proving that for each weakly compact operator T : L1()  L1() or T : C()  C(), the operator T2 is compact, a fact which is important from the point of view that there is a nice spectral theory for compact operators and operators whose squares are compact. There is an extensive literature involving the Dunford-Pettis property. Almost all the articles and books in our list of references contain some information about this property, but there are plenty more that could have been listed. The reader is for instance referred to [4], [5], [7], [8], [10], [17] and [24] for information on the role of the DPP in different areas of Banach space theory. In this dissertation, however, we are motivated by the two papers [7] and [8] to study alternative Dunford-Pettis properties, to introduce a scale of (new) alternative Dunford-Pettis properties, which we call DP*-properties of order p (briefly denoted by DP*P), and to consider characterisations of Banach spaces with these properties as well as applications thereof to polynomials and holomorphic functions on Banach spaces. In the paper [8] the class Cp(X, Y) of p-convergent operators from a Banach space X to a Banach space Y is introduced. Replacing the requirement that weakly compact operators on X should be completely continuous in the case of the DPP for X (as is mentioned above) by “weakly compact operators on X should be p-convergent", an alternative Dunford-Pettis property (called the Dunford-Pettis property of order p) is introduced. More precisely, if 1 ≤ p ≤ , a Banach space X is said to have DPPp if the inclusion W(X, Y)  Cp(X, Y) holds for all Banach spaces Y . Here W(X, Y) denotes the family of all weakly compact operators from X to Y. We now have a scale of “Dunford-Pettis like properties" in the sense that all Banach spaces have the DPP1, if p < q, then each Banach space with the DPPq also has the DPPp and the strongest property, namely the DPP1 coincides with the DPP. In the paper [7] the authors study a property on Banach spaces (called the DP*-property, or briey the DP*P) which is stronger than the DPP, in the sense that if a Banach space has this property then it also has DPP. We say X has the DP*P, when all weakly compact sets in X are limited, i.e. each sequence (x*n)  X * in the dual space of X which converges weak* to 0, also converges uniformly (to 0) on all weakly compact sets in X. It turns out that this property is equivalent to another property on Banach spaces which is introduced in [17] (and which is called the *-Dunford-Pettis property) as follows: We say a Banach space X has the *-Dunford-Pettis property if for all weakly null sequences (xn) in X and all weak* null sequences (x*n) in X*, we have x*n(xn) n 0. After a thorough study of the DP*P, including characterisations and examples of Banach spaces with the DP*P, the authors in [7] consider some applications to polynomials and analytic functions on Banach spaces. Following an extensive literature study and in depth research into the techniques of proof relevant to this research field, we are able to present a thorough discussion of the results in [7] and [8] as well as some selected (relevant) results from other papers (for instance, [2] and [17]). This we do in Chapter 2 of the dissertation. The starting point (in Section 2.1 of Chapter 2) is the introduction of the so called p-convergent operators, being those bounded linear operators T : X  Y which transform weakly p-summable sequences into norm-null sequences, as well as the so called weakly p-convergent sequences in Banach spaces, being those sequences (xn) in a Banach space X for which there exists an x  X such that the sequence (xn - x) is weakly p-summable. Using these concepts, we state and prove an important characterisation (from the paper [8]) of Banach spaces with DPPp. In Section 2.2 (of Chapter 2) we continue to report on the results of the paper [7], where the DP*P on Banach spaces is introduced. We focus on the characterisation of Banach spaces with DP*P, obtaining among others that a Banach space X has DP*P if and only if for all weakly null sequences (xn) in X and all weak* null sequences (x*n) in X*, we have x*n(xn) n 0. An important characterisation of the DP*P considered in this section is the fact that X has DP*P if and only if every T  L(X, c0) is completely continuous. This result proves to be of fundamental importance in the study of the DP*P and its application to results on polynomials and holomorphic functions on Banach spaces. To be able to report on the applications of the DP*P in the context of homogeneous polynomials and analytic functions on Banach spaces, we embark on a study of “Complex Analysis in Banach spaces" (mostly with the focus on homogeneous polynomials and analytic functions on Banach spaces). This we do in Chapter 3; the content of the chapter is mostly based on work in the books [23] and [14], but also on the work in some articles such as [15]. After we have discussed the relevant theory of complex analysis in Banach spaces in Chapter 3, we devote Chapter 4 to considering properties of polynomials and analytic functions on Banach spaces with DP*P. The discussion in Chapter 4 is based on the applications of DP*P in the paper [7]. Finally, in Chapter 5 of the dissertation, we contribute to the study of “Dunford-Pettis like properties" by introducing the Banach space property “DP*P of order p", or briefly the DP*Pp for Banach spaces. Using the concept “weakly p-convergent sequence in Banach spaces" as is defined in [8], we define weakly-p-compact sets in Banach spaces. Then a Banach space X is said to have the DP*-property of order p (for 1 ≤ p ≤ ) if all weakly-p-compact sets in X are limited. In short, we say X has DP*Pp. As in [8] (where the DPPp is introduced), we now have a scale of DP*P-like properties, in the sense that all Banach spaces have DP*P1 and if p < q and X has DP*Pq then it has DP*Pp. The strongest property DP*P coincides with DP*P. We prove characterisations of Banach spaces with DP*Pp, discuss some examples and then consider applications to polynomials and analytic functions on Banach spaces. Our results and techniques in this chapter depend very much on the results obtained in the previous three chapters, but now we have to find our own correct definitions and formulations of results within this new context. We do this with some success in Sections 5.1 and 5.2 of Chapter 5. Chapter 1 of this dissertation provides a wide range of concepts and results in Banach spaces and the theory of vector sequence spaces (some of them very deep results from books listed in the bibliography). These results are mostly well known, but they are scattered in the literature - they are discussed in Chapter 1 (some with proof, others without proof, depending on the importance of the arguments in the proofs for later use and depending on the detail with which the results are discussed elsewhere in the literature) with the intention to provide an exposition which is mostly self contained and which will be comfortably accessible for graduate students. The dissertation reflects the outcome of our investigation in which we set ourselves the following goals: 1. Obtain a thorough understanding of the Dunford-Pettis property and some related (both weaker and stronger) properties that have been studied in the literature. 2. Focusing on the work in the paper [8], understand the role played in the study of difierent classes of operators by a scale of properties on Banach spaces, called the DPPp, which are weaker than the DP-property and which are introduced in [8] by using the weakly p-summable sequences in X and weakly null sequences in X*. 3. Focusing on the work in the paper [7], investigate the DP*P for Banach spaces, which is the exact property to answer a question of Pelczynsky's regarding when every symmetric bilinear separately compact map X x X  c0 is completely continuous. 4. Based on the ideas intertwined in the work of the paper [8] in the study of a scale of DP-properties and the work in the paper [7], introduce the DP*Pp on Banach spaces and investigate their applications to spaces of operators and in the theory of polynomials and analytic mappings on Banach spaces. Thereby, not only extending the results in [7] to a larger family of Banach spaces, but also to find an answer to the question: “When will every symmetric bilinear separately compact map X x X  c0 be p-convergent?"
Thesis (M.Sc. (Mathematics))--North-West University, Potchefstroom Campus, 2012.

Submitted by Leonardo Cavalcante (leo.ocavalcante@gmail.com) on 2018-05-03T12:04:50Z No. of bitstreams: 1 Arquivototal.pdf: 1304658 bytes, checksum: e4e550beeae66c0949fd33c9fa86db45 (MD5)
Made available in DSpace on 2018-05-03T12:04:50Z (GMT). No. of bitstreams: 1 Arquivototal.pdf: 1304658 bytes, checksum: e4e550beeae66c0949fd33c9fa86db45 (MD5) Previous issue date: 2017-06-09
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Abstract indisponível neste campo - O PDF foi entregue protegido para cópia
Resumo indisponível neste campo - O PDF foi entregue protegido para cópia

Submitted by Leonardo Cavalcante (leo.ocavalcante@gmail.com) on 2018-04-23T21:42:23Z No. of bitstreams: 1 Arquivototal.pdf: 889863 bytes, checksum: feeec177f9d947c98727574b765d8acb (MD5)
Made available in DSpace on 2018-04-23T21:42:23Z (GMT). No. of bitstreams: 1 Arquivototal.pdf: 889863 bytes, checksum: feeec177f9d947c98727574b765d8acb (MD5) Previous issue date: 2017-07-25
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
In this work, we study the notion of index of summability for pairs of Banach spaces. This index plays the role of a kind of “measure” of how the space of m-homogeneous polynomials from E to F (or the space of multilinear operators of E1×···×Em to F) are far from being the space of absolutely summing m-homogeneous polynomials (or with the space of multiple summing multilinear operators). In some cases the optimal index of summability is presented.
Neste trabalho, estudamos a noção de índice de somabilidade para pares de espaços de Banach. Esse índice desempenha o papel de um tipo de \medida" de como o espaço dos polinômios m-homogêneos de E em F (ou o espaço dos operadores multilineares de E Em em F) está longe de coincidir com o espaço dos polinômios m- homogêneos absolutamente somantes (ou com o espaço dos operadores multilineares multiplo somantes). Em alguns casos o índice ótimo de somabilidade e apresentado. Palavras-chave: Polinômios absolutamente somantes, operadores multilineares absolutamente somantes, espaços de Banach, índice de somabilidade.

Submitted by ANA KARLA PEREIRA RODRIGUES (anakarla_@hotmail.com) on 2017-08-22T16:24:35Z No. of bitstreams: 1 arquivototal.pdf: 1096557 bytes, checksum: 096bafe0cd5d1cf118a6fa1546070e5d (MD5)
Made available in DSpace on 2017-08-22T16:24:35Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1096557 bytes, checksum: 096bafe0cd5d1cf118a6fa1546070e5d (MD5) Previous issue date: 2016-03-03
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
In this work we study a recent general version of the Extrapolation Theorem, due to Botelho, Pellegrino, Santos and Seoane-Sep ulveda [6] that improves and uni es a number of known Extrapolation-type theorems for classes of mappings that generalize the ideal of absolutely p-summing linear operators.
Neste trabalho, dissertamos sobre uma recente vers~ao geral do Teorema de Extrapola c~ao, devida a Botelho, Pellegrino, Santos e Seoane-Sep ulveda [6], que melhora e uni ca v arios teoremas do tipo Extrapola c~ao para certas classes de fun c~oes que generalizam o ideal dos operadores lineares absolutamente p-somantes.

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-10-11T18:36:34Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese Adriano Thiago.pdf: 1085326 bytes, checksum: 498b2bcfd47961466edce3360e11a858 (MD5)
Made available in DSpace on 2016-10-11T18:36:34Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese Adriano Thiago.pdf: 1085326 bytes, checksum: 498b2bcfd47961466edce3360e11a858 (MD5) Previous issue date: 2016-06-17
Neste trabalho estudamos algumas extens˜oes do conceito de operadores multilineares absolutamente somantes, generalizamos alguns resultados conhecidos e respondemos parcialmente alguns problemas abertos. Para a classe das aplica¸c˜oes absolutamente (p; q; r)-somantes, obtemos alguns resultados de coincidˆencia e inclus˜ao e mostramos que o ideal de polinˆomios absolutamente (p; q; r)-somantes n˜ao ´e corente, de acordo com a no¸c˜ao de ideais coerentes devida a D. Carando, V. Dimant e S. Muro. Para contornar esta falha, introduzimos o conceito de aplica¸c˜oes m´ultiplo (p; q; r)-somantes e mostramos que, com essa nova abordagem, o ideal de polinˆomios m´ultiplo (p; q; r)- somantes ´e coerente e compat´ıvel com o ideal de operadores lineares absolutamente (p; q; r)-somantes.
In this work we investigate some extensions of the concept of absolutely summing operators, generalize some known results and provide partial answers to some open questions. For the class of absolutely (p; q; r)-summing mappings we obtain some inclusion and coincidence results and show that the ideal of absolutely (p; q; r)-summing polynomials is not coherent, according to the notion of coherent ideals due to D. Carando, V. Dimant and S. Muro. In order to bypass this deficiency, we introduce the concept of multiple (p; q; r)-summing multilinear and polynomial operators and show that, with this new approach, the ideal of multiple (p; q; r)-summing polynomials is coherent and compatible with the ideal of absolutely (p; q; r)-summing operators.

We define and study a new family of Banach spaces, the J ames-Schreier spaces, cre- ated by combining key properties in the definitions of two important classical Banach spaces, namely James' quasi-reflexive space and Schreier's space. We explore both the Banach space and Banach algebra theory of these spaces. The new spaces inherit aspects of both parent spaces: our main results are that the J ames-Schreier spaces each have a shrinking basis, do not embed in a Banach space with an unconditional basis, and each of their closed, infinite-dimensional subspaces contains a copy of Co. As Banach sequence algebras each James-Schreier space has a bounded approx- imate identity and is weakly amenable but not amenable, and the bidual and multiplier - algebra are isometrically isomorphic. We approach our study of Banach sequence algebras from the point of view of Schauder basis theory, in particular looking at those Banach sequence algebras for which the unit vectors form an unconditional or shrinking basis. We finally show that for each Banach space X with an unconditional basis we may construct a James-like Banach sequence algebra j(X) with a bounded approximate identity, and give a condition on the shift operators acting on X which implies that j(X) will contain a copy of X as a complemented ideal and hence not be amenable.

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 no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8312
Palancia

We study the geometric classification of Banach spaces via Lipschitz, uniformly continuous, and coarse mappings. We prove that a Banach space which is uniformly homeomorphic to a linear quotient of lp is itself a linear quotient of lp when p<2. We show that a Banach space which is Lipschitz universal for all separable metric spaces cannot be asymptotically uniformly convex. Next we consider coarse embedding maps as defined by Gromov, and show that lp cannot coarsely embed into a Hilbert space when p> 2. We then build upon the method of this proof to show that a quasi-Banach space coarsely embeds into a Hilbert space if and only if it is isomorphic to a subspace of L0(??) for some probability space (Ω,B,??).

The notion of asymptotic structure of an infinite dimensional Banach space was introduced by Maurey, Milman and Tomczak-Jaegermann. The asymptotic structure consists of those finite dimensional spaces which can be found everywhere `at infinity'. These are defined as the spaces for which there is a winning strategy in a certain vector game. The above authors introduced the class of asymptotic $\ell_p$ spaces, which are the spaces having simplest possible asymptotic structure. Key examples of such spaces are Tsirelson's space and James' space. We prove some new properties of general asymptotic $\ell_p$ spaces and also compare the notion of asymptotic $\ell_2$ with other notions of asymptotic Hilbert space behaviour such as weak Hilbert and asymptotically Hilbertian. We study some properties of smooth functions defined on subsets of asymptotic $\ell_\infty$ spaces. Using these results we show that that an asymptotic $\ell_\infty$ space which has a suitably smooth norm is isomorphically polyhedral, and therefore admits an equivalent analytic norm. We give a sufficient condition for a generalized Orlicz space to be a stabilized asymptotic $\ell_\infty$ space, and hence obtain some new examples of asymptotic $\ell_\infty$ spaces. We also show that every generalized Orlicz space which is stabilized asymptotic $\ell_\infty$ is isomorphically polyhedral. In 1991 Gowers and Maurey constructed the first example of a space which did not contain an unconditional basic sequence. In fact their example had a stronger property, namely that it was hereditarily indecomposable. The space they constructed was `$\ell_1$-like' in the sense that for any $n$ successive vectors $x_1 < \ldots < x_n$, $\frac{1}{f(n)} \sum_{i=1}^n \| x_i \| \leq \| \sum_{i=1}^n x_i \| \leq \sum_{i=1}^n \| x_i \|,$ where $ f(n) = \log_2 (n+1) $. We present an adaptation of this construction to obtain, for each $ p \in (1, \infty)$, an hereditarily indecomposable Banach space, which is `$\ell_p$-like' in the sense described above. We give some sufficient conditions on the set of types, $\mathscr{T}(X)$, for a Banach space $X$ to contain almost isometric copies of $\ell_p$ (for some $p \in [1, \infty)$) or of $c_0$. These conditions involve compactness of certain subsets of $\mathscr{T}(X)$ in the strong topology. The proof of these results relies heavily on spreading model techniques. We give two examples of classes of spaces which satisfy these conditions. The first class of examples were introduced by Kalton, and have a structural property known as Property (M). The second class of examples are certain generalized Tsirelson spaces. We introduce the class of stopping time Banach spaces which generalize a space introduced by Rosenthal and first studied by Bang and Odell. We look at subspaces of these spaces which are generated by sequences of independent random variables and we show that they are isomorphic to (generalized) Orlicz spaces. We deduce also that every Orlicz space, $h_\phi$, embeds isomorphically in the stopping time Banach space of Rosenthal. We show also, by using a suitable independence condition, that stopping time Banach spaces also contain subspaces isomorphic to mixtures of Orlicz spaces.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb. 20, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Professor Nigel J. Kalton. Vita. Includes bibliographical references.

Tensor products of Banach Spaces are studied. An introduction to tensor products is given. Some results concerning the reciprocal Dunford-Pettis Property due to Emmanuele are presented. Pelczyriski's property (V) and (V)-sets are studied. It will be shown that if X and Y are Banach spaces with property (V) and every integral operator from X into Y* is compact, then the (V)-subsets of (X⊗F)* are weak* sequentially compact. This in turn will be used to prove some stronger convergence results for (V)-subsets of C(Ω,X)*.

The definition of semi-hyperbolic dynamical systems generated by Lipschitz continuous and not necessarily invertible mappings in Banach spaces is presented in this thesis. Like hyperbolic mappings, they involve a splitting into stable and unstable spaces, but a slight leakage from the strict invariance of the spaces is possible and the unstable subspaces are assumed to be finite dimensional. Bi-shadowing is a combination of the concepts of shadowing and inverse shadowing and is usually used to compare pseudo-trajectories calculated by a computer with the true trajectories. In this thesis, the concept of bi-shadowing in a Banach space is defined and proved for semi-hyperbolic dynamical systems generated by Lipschitz mappings. As an application to the concept of bishadowing, linear delay differential equations are shown to be bi-shadowing with respect to pseudo-trajectories generated by nonlinear small perturbations of the linear delay equation. This shows robustness of solutions of the linear delay equation with respect to small nonlinear perturbations. Complicated dynamical behaviour is often a consequence of the expansivity of a dynamical system. Semi-hyperbolic dynamical systems generated by Lipschitz mappings on a Banach space are shown to be exponentially expansive, and explicit rates of expansion are determined. The result is applied to a nonsmooth noninvertible system generated by delay differential equation. It is shown that semi-hyperbolic mappings are locally φ-contracting, where -0 is the Hausdorff measure of noncompactness, and that a linear operator is semi-hyperbolic if and only if it is φ-contracting and has no spectral values on the unit circle. The definition of φ-bi-shadowing is given and it is shown that semi-hyperbolic mappings in Banach spaces are φ-bi-shadowing with respect to locally condensing continuous comparison mappings. The result is applied to linear delay differential equations of neutral type with nonsmooth perturbations. Finally, it is shown that a small delay perturbation of an ordinary differential equation with a homoclinic trajectory is ‘chaotic’.

Our aim in this research was to study monotone operators in Banach spaces. In particular, the most important concept in this theory, the maximal monotone operators. Here we make an attempt to describe most of the important results and concepts on maximal monotone operators and how they all tie together. We will take a brief look at subdifferentials, which generalize the notion of a derivative. The subdifferential is a maximal monotone operator and it has proved to be of fundamental importance for the study of maximal monotone operators. The theory of maximal monotone operators is somewhat complete in reflexive Banach spaces. However, in nonreflexive Banach spaces it is still to be developed fully. As such, here we will describe most of the important results about maximal monotone operators in Banach spaces and we will distinguish between the reflexive Banach spaces and nonreflexive Banach spaces when a property is known to hold only in reflexive Banach spaces. In the latter case, we will state what the corresponding situation is in nonreflexive Banach spaces and we will give counter examples whenever such a result is known to fail in nonreflexive Banach spaces. The representations of monotone operators by convex functions have found to be extremely useful for the study of maximal monotone operators and it has generated a lot of interest of late. We will discuss some of those key representations and their properties. We will also demonstrate how these representations could be utilized to obtain results about maximal monotone operators. We have included a discussion about the very important Rockafellar sum theorem and some its generalizations. This key result and its generalizations have only been proved in reflexive Banach spaces. We will also discuss several special cases where the Rockafellar sum theorem is known to be true in nonreflexive Banach spaces. The subclasses which provide a basis for the study of monotone operators in nonreflexive Banach spaces are also discussed here

We define a universal Fréchet set S of a Banach space Y as a subset containing a point of Fréchet differentiability of every Lipschitz function g : Y -> R. We prove a sufficient condition for S to be a universal Fréchet set and use this to construct new examples of such sets. The strongest such result says that in a non-zero Banach space Y with separable dual one can find a universal Fréchet set S ⊆ Y that is closed, bounded and has Hausdorff dimension one.

The central idea in this thesis is the introduction of a new isometric invariant of a Banach space. This is Property AI-I. A Banach space has Property AI-I if whenever a finite metric space almost-isometrically embeds into the space, it isometrically embeds. To study this property we introduce two further properties that can be thought of as finite metric variants of Dvoretzky's Theorem and Krivine's Theorem. We say that a Banach space satisfies the Finite Isometric Dvoretzky Property (FIDP) if it contains every finite subset of $\ell_2$ isometrically. We say that a Banach space has the Finite Isometric Krivine Property (FIKP) if whenever $\ell_p$ is finitely representable in the space then it contains every subset of $\ell_p$ isometrically. We show that every infinite-dimensional Banach space \emph{nearly} has FIDP and every Banach space nearly has FIKP. We then use convexity arguments to demonstrate that not every Banach space has FIKP, and thus we can exhibit classes of Banach spaces that fail to have Property AI-I. The methods used break down when one attempts to prove that there is a Banach space without FIDP and we conjecture that every infinite-dimensional Banach space has Property FIDP.

The aim of this thesis is to provide a survey of the topic of composition operators on spaces of (equivalence classes of) measurable functions and attempt to unify some of the most important results contained in the literature. A large class of these spaces can be equipped with norms turning them into Banach lattices. These spaces are called Banach function spaces and examples include the Lebesgue, Lorentz, Orlicz and Orlicz-Lorentz spaces.

[EN] The Ph.D. thesis "Weighted Banach Spaces of harmonic functions" presented here, treats several topics of functional analysis such as weights, composition operators, Fréchet and Gâteaux differentiability of the norm and isomorphism classes. The work is divided into four chapters that are preceded by one in which we introduce the notation and the well-known properties that we use in the proofs in the rest of the chapters. In the first chapter we study Banach spaces of harmonic functions on open sets of R^d endowed with weighted supremun norms. We define the harmonic associated weight, we explain its properties, we compare it with the holomorphic associated weight introduced by Bierstedt, Bonet and Taskinen, and we find differences and conditions under which they are exactly the same and conditions under which they are equivalent. The second chapter is devoted to the analysis of composition operators with holomorphic symbol between weighted Banach spaces of pluriharmonic functions. We characterize the continuity, the compactness and the essential norm of composition operators among these spaces in terms of their weights, thus extending the results of Bonet, Taskinen, Lindström, Wolf, Contreras, Montes and others for composition operators between spaces of holomorphic functions. We prove that for each value of the interval [0,1] there is a composition operator between weighted spaces of harmonic functions such that its essential norm attains this value. Most of the contents of Chapters 1 and 2 have been published by E. Jordá and the author in [48]. The third chapter is related with the study of Gâteaux and Fréchet differentiability of the norm. The \v{S}mulyan criterion states that the norm of a real Banach space X is Gâteaux differentiable at x\inX if and only if there exists x^* in the unit ball of the dual of X weak^* exposed by x and the norm is Fréchet differentiable at x if and only if x^* is weak^* strongly exposed in the unit ball of the dual of X by x. We show that in this criterion the unit ball of the dual of X can be replaced by a smaller convenient set, and we apply this extended criterion to characterize the points of Gâteaux and Fréchet differentiability of the norm of some spaces of harmonic functions and continuous functions with vector values. Starting from these results we get an easy proof of the theorem about the Gâteaux differentiability of the norm for spaces of compact linear operators announced by Heinrich and published without proof. Moreover, these results allow us to obtain applications to classical Banach spaces as the space H^\infty of bounded holomorphic functions in the disc and the algebra A(\overline{\D}) of continuous functions on \overline{\D} which are holomorphic on \D. The content of this chapter has been included by E. Jordá and the author in [47]. Finally, in the forth chapter we show that for any open set U of R^d and weight v on U, the space hv0(U) of harmonic functions such that multiplied by the weight vanishes at the boundary on U is almost isometric to a closed subspace of c0, extending a theorem due to Bonet and Wolf for the spaces of holomorphic functions Hv0(U) on open sets U of C^d. Likewise, we also study the geometry of these weighted spaces inspired by a work of Boyd and Rueda, examining topics such as the v-boundary and v-peak points and we give the conditions that provide examples where hv0(U) cannot be isometric to c0. For a balanced open set U of R^d, some geometrical conditions in U and convexity in the weight v ensure that hv0(U) is not rotund. These results have been published by E. Jordá and the author [46].
[ES] La presente memoria, "Espacios de Banach ponderados de funciones armónicas ", trata diversos tópicos del análisis funcional, como son las funciones peso, los operadores de composición, la diferenciabilidad Fréchet y Gâteaux de la norma y las clases de isomorfismos. El trabajo está dividido en cuatro capítulos precedidos de uno inicial en el que introducimos la notación y las propiedades conocidas que usamos en las demostraciones del resto de capítulos. En el primer capítulo estudiamos espacios de Banach de funciones armónicas en conjuntos abiertos de R^d dotados de normas del supremo ponderadas. Definimos el peso asociado armónico, explicamos sus propiedades, lo comparamos con el peso asociado holomorfo introducido por Bierstedt, Bonet y Taskinen, y encontramos diferencias y condiciones para que sean exactamente iguales y condiciones para que sean equivalentes. El capítulo segundo está dedicado al análisis de los operadores de composición con símbolo holomorfo entre espacios de Banach ponderados de funciones pluriarmónicas. Caracterizamos la continuidad, la compacidad y la norma esencial de operadores de composición entre estos espacios en términos de los pesos, extendiendo los resultados de Bonet, Taskinen, Lindström, Wolf, Contreras, Montes y otros para operadores de composición entre espacios de funciones holomorfas. Probamos que para todo valor del intervalo [0,1] existe un operador de composición sobre espacios ponderados de funciones armónicas tal que su norma esencial alcanza dicho valor. La mayoría de los contenidos de los capítulos 1 y 2 han sido publicados por E. Jordá y la autora en [48]. El capítulo tercero está relacionado con el estudio de la diferenciabilidad Gâteaux y Fréchet de la norma. El criterio de \v{S}mulyan establece que la norma de un espacio de Banach real X es Gâteaux diferenciable en x\in X si y sólo si existe x^* en la bola unidad del dual de X débil expuesto por x y la norma es Fréchet diferenciable en x si y sólo si x^*es débil fuertemente expuesto en la bola unidad del dual de X por x. Mostramos que en este criterio la bola del dual de X puede ser reemplazada por un conjunto conveniente más pequeño, y aplicamos este criterio extendido para caracterizar los puntos de diferenciabilidad Gâteaux y Fréchet de la norma de algunos espacios de funciones armónicas y continuas con valores vectoriales. A partir de estos resultados conseguimos una prueba sencilla del teorema sobre la diferenciabilidad Gâteaux de la norma de espacios de operadores lineales compactos enunciado por Heinrich y publicado sin la prueba. Además, éstos nos permiten obtener aplicaciones para espacios de Banach clásicos como H^\infty de funciones holomorfas acotadas en el disco y A(\overline{\D}) de funciones continuas en \overline{\D} que son holomorfas en \D. Los contenidos de este capítulo han sido incluidos por E. Jordá y la autora en [47]. Finalmente, en el capítulo cuarto mostramos que para cualquier abierto U contenido en R^d y cualquier peso v en U, el espacio hv0(U), de funciones armónicas tales que multiplicadas por el peso desaparecen en el infinito de U, es casi isométrico a un subespacio cerrado de c0, extendiendo un teorema debido a Bonet y Wolf para los espacios de funciones holomorfas Hv0(U) en abiertos U de C^d. Así mismo, inspirados por un trabajo de Boyd y Rueda también estudiamos la geometría de estos espacios ponderados examinando tópicos como la v-frontera y los puntos v-peak y damos las condiciones que proporcionan ejemplos donde hv0(U) no puede ser isométrico a c0. Para un conjunto abierto equilibrado U de R^d, algunas condiciones geométricas en U y sobre convexidad en el peso v aseguran que hv0(U) no es rotundo. Estos resultados han sido publicados por E. Jordá y la autora en [46].
[CAT] La present memòria, "Espais de Banach ponderats de funcions harmòniques", tracta diversos tòpics de l'anàlisi funcional, com són les funcions pes, els operadors de composició, la diferenciabilitat Fréchet i Gâteaux de la norma i les clases d'isomorfismes. El treball està dividit en quatre capítols precedits d'un d'inicial en què introduïm la notació i les propietats conegudes que fem servir en les demostracions de la resta de capítols. En el primer capítol estudiem espais de Banach de funcions harmòniques en conjunts oberts de R^d dotats de normes del suprem ponderades. Definim el pes associat harmònic, expliquem les seues propietats, el comparem amb el pes associat holomorf introduït per Bierstedt, Bonet i Taskinen, i trobem diferències i condicions perquè siguen exactament iguals i condicions perquè siguen equivalents. El capítol segon està dedicat a l'anàlisi dels operadors de composició amb símbol holomorf entre espais de Banach ponderats de funcions pluriharmòniques. Caracteritzem la continuïtat, la compacitat i la norma essencial d'operadors de composició entre aquests espais en termes dels pesos, estenent els resultats de Bonet, Taskinen, Lindström, Wolf, Contreras, Montes i altres per a operadors de composició entre espais de funcions holomorfes. Provem que per a tot valor de l'interval [0,1] hi ha un operador de composició sobre espais ponderats de funcions harmòniques tal que la seua norma essencial arriba aquest valor. La majoria dels continguts dels capítols 1 i 2 han estat publicats per E. Jordá i l'autora en [48]. El capítol tercer està relacionat amb l'estudi de la diferenciabilitat Gâteaux y Fréchet de la norma. El criteri de \v{S}mulyan estableix que la norma d'un espai de Banach real X és Gâteaux diferenciable en x\inX si i només si existeix x^* a la bola unitat del dual de X feble exposat per x i la norma és Fréchet diferenciable en x si i només si x^* és feble fortament exposat a la bola unitat del dual de X per x. Mostrem que en aquest criteri la bola del dual de X pot ser substituïda per un conjunt convenient més petit, i apliquem aquest criteri estès per caracteritzar els punts de diferenciabilitat Gâteaux i Fréchet de la norma d'alguns espais de funcions harmòniques i contínues amb valors vectorials. A partir d'aquests resultats aconseguim una prova senzilla del teorema sobre la diferenciabilitat Gâteaux de la norma d'espais d'operadors lineals compactes enunciat per Heinrich i publicat sense la prova. A més, aquests ens permeten obtenir aplicacions per a espais de Banach clàssics com l'espai H^\infty de funcions holomorfes acotades en el disc i l'àlgebra A(\overline{\D}) de funcions contínues en \overline{\D} que són holomorfes en \D. Els continguts d'aquest capítol han estat inclosos per E. Jordá i l'autora en [47]. Finalment, en el capítol quart mostrem que per a qualsevol conjunt obert U de R^d i qualsevol pes v en U, l'espai hv0(U), de funcions harmòniques tals que multiplicades pel pes desapareixen en el infinit d'U, és gairebé isomètric a un subespai tancat de c0, estenent un teorema degut a Bonet y Wolf per als espais de funcions holomorfes Hv0(U) en oberts U de C^d. Així mateix, inspirats per un treball de Boyd i Rueda també estudiem la geometria d'aquests espais ponderats examinant tòpics com la v-frontera i els punts v-peak i donem les condicions que proporcionen exemples on hv0(U) no pot ser isomètric a c0. Per a un conjunt obert equilibrat U de R^d, algunes condicions geomètriques en U i sobre convexitat en el pes v asseguren que hv0(U) no és rotund. Aquests resultats han estat publicats per E. Jordá i l'autora en [46].
Zarco García, AM. (2015). Weighted Banach spaces of harmonic functions [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/56461
TESIS

A continuous convex function on an open interval of the real line is differentiable everywhere except on a countable subset of its domain. There has been interest in the problem of characterizing those Banach spaces where the continuous functions exhibit similar differentiability properties. In this paper we show that if a Banach space E has property (H*) and B_E• is weak* sequentially compact, then E is an Asplund space. In the case where the space is weakly compactly generated, it is shown that property (H*) is equivalent for the space to admit an equivalent Frechet differentiable norm. Moreover, we define the SH* spaces, show that every SH* space is an Asplund space, and show that every weakly sequentially complete SH* space is reflexive. Also, we study the relation between property (H*) and the asymptotic norming property (ANP). By a slight modification of the ANP we define the ANP*, and show that if the dual of a Banach spaces has the ANP*-I then the space admits an equivalent Fréchet differentiability norm, and that the ANP*-II is equivalent to the space having property (H*) and the closed unit ball of the dual is weak* sequentially compact. Also, we show that in the dual of a weakly countably determined Banach space all the ANP-K'S are equivalent, and they are equivalent for the predual to have property (H*).

The purpose of this paper is to explore certain properties of Banach spaces. The first chapter begins with basic definitions, includes examples of Banach spaces, and concludes with some properties of continuous linear functionals. In the second chapter, dimension is discussed; then one version of the Hahn-Banach Theorem is presented. The third chapter focuses on dual spaces and includes an example using co, RI, and e'. The role of locally convex spaces is also explored in this chapter. In the fourth chapter, several more theorems concerning dual spaces and related topologies are presented. The final chapter focuses on reflexive spaces. In the main theorem, the relation between compactness and reflexivity is examined. The paper concludes with an example of a non-reflexive space.

"A natural process in examining properties of Banach spaces is to see if a Banach space can be decomposed into simpler Banach spaces; in other words, to see if a Banach space has complemented subspaces. This thesis concentrates on three main aspects of this problem: norm of projections of a Banach space onto its finite dimensional subspaces; a class of Banach spaces, each of which has a large number of infinite dimensional complemented subspaces; and methods of finding Banach spaces which have uncomplemented subspaces, where the subspaces and the quotient spaces are chosen as well-known classical sequence spaces (finding non-trivial twisted sums)." --Abstract.
Master of Mathematical Sciences

"A natural process in examining properties of Banach spaces is to see if a Banach space can be decomposed into simpler Banach spaces; in other words, to see if a Banach space has complemented subspaces. This thesis concentrates on three main aspects of this problem: norm of projections of a Banach space onto its finite dimensional subspaces; a class of Banach spaces, each of which has a large number of infinite dimensional complemented subspaces; and methods of finding Banach spaces which have uncomplemented subspaces, where the subspaces and the quotient spaces are chosen as well-known classical sequence spaces (finding non-trivial twisted sums)." --Abstract.
Master of Mathematical Sciences

The principal objects of study in this thesis are arbitrary spectral families, E, on a complex Banach space X. The central theme is the relationship between the geometry of X and the p-variation of E. We show that provided X is super- reflexive, then given any E, there exists a value 1 · p < 1, depending only on E and X, such that var p(E) < 1. If X is uniformly smooth we provide an explicit range of such values p, which depends only on E and the modulus of convexity of X*, delta X*(.).

A set S in a Banach space X is called a universal differentiability set if S contains a point of differentiability of every Lipschitz function f : X -> R. The present thesis investigates the nature of such sets. We uncover examples of exceptionally small universal differentiability sets and prove that all universal differentiability sets satisfy certain strong structural conditions. Later, we expand our focus to properties of more general absolutely continuous functions.

Bibliography: leaves 87-90.
Function spaces have been a useful tool in probing the convergence of sequences of functions. The theory seems to have been triggered off by the works of Ascoli [36], Arzelà [37] and Hadamard [38]. In this thesis, we consider the space of continuous functions from a topological space X into the reals R, which we denote C(X).

The main theme of the thesis is the study of continuity and approximation problems, involving matrix-valued and vector-valued Hardy spaces on the unit disc ID and its boundary T in the complex plane. The first part of the thesis looks at the factorization of square matrix-valued boundary functions, beginning with spectral factorization in Chapter 2. Then ideas involving approximations with inner and outer functions are used to solve a matrix analogue of the Douglas-Rudin problem in Chapter 3. In both cases, considerable considerable extra difficulties are created by the noncommutativity of matrix multiplication. More specifically, we show that the matrix spectral factorization mapping is sequentially continuous from LP to H2p (where 1