National Repository of Grey Literature 87 records found  beginprevious44 - 53nextend  jump to record: Search took 0.00 seconds. 
Optimality of function spaces for classical integral operators
Mihula, Zdeněk ; Pick, Luboš (advisor)
We investigate optimal partnership of rearrangement-invariant Banach func- tion spaces for the Hilbert transform and the Riesz potential. We establish sharp theorems which characterize optimal action of these operators on such spaces. These results enable us to construct optimal domain (i.e. the largest) and op- timal range (i.e. the smallest) partner spaces when the other space is given. We illustrate the obtained results by non-trivial examples involving Generalized Lorentz-Zygmund spaces with broken logarithmic functions. The method is pre- sented in such a way that it should be easily adaptable to other appropriate operators. 1
Boundedness of the average operator on Orlicz sequence spaces
Krejčí, Jan ; Pick, Luboš (advisor) ; Hencl, Stanislav (referee)
The goal of this thesis is to characterize the Average operator on Orlicz sequence spaces and to give a condition equivalent to ∆0 2. 1
Integral and supremal operators on weighted function spaces
Křepela, Martin ; Pick, Luboš (advisor) ; Sickel, Winfried (referee) ; Tichonov, Sergey (referee)
Title: Integral and Supremal Operators on Weighted Function Spaces Author: Martin Křepela Department: Department of Mathematical Analysis Supervisor: prof. RNDr. Luboš Pick, CSc., DSc., Department of Mathematical Analysis Abstract: The common topic of this thesis is boundedness of integral and supre- mal operators between function spaces with weights. The results of this work have the form of characterizations of validity of weighted operator inequalities for appropriate cones of functions. The outcome can be divided into three cate- gories according to the particular type of studied operators and function spaces. The first part involves a convolution operator acting on general weighted Lorentz spaces of types Λ, Γ and S defined in terms of the nonincreasing rear- rangement, Hardy-Littlewood maximal function and the difference of these two, respectively. It is characterized when a convolution-type operator with a fixed kernel is bounded between the aforementioned function spaces. Furthermore, weighted Young-type convolution inequalities are obtained and a certain optima- lity property of involved rearrangement-invariant domain spaces is proved. The additional provided information includes a comparison of the results to the pre- viously known ones and an overview of basic properties of some new function spaces...
Integral operators on function spaces
Peša, Dalimil ; Pick, Luboš (advisor) ; Nekvinda, Aleš (referee)
In this thesis, we consider Lorentz-Karamata spaces with slowly varying fuc- tions and study their properties. We first provide simpler definition of slowly varying functions and derive some of their properties. We then consider Lorentz-Karamata functionals over an arbi- trary sigma-finite measure space equipped with a non-atomic measure and corre- sponding Lorentz-Karamata spaces. We characterise non-triviality of said spaces, then study when they are equivalent to a Banach function space and obtain mul- titude of conditions, either sufficient or necessary. We further study embeddings between Lorentz-Karamata spaces and provide a partial characterisation. At last, we try to describe the associate spaces of Lorentz-Karamata spaces and succeed even in some of the limiting cases. Our contribution is mainly the characterisation of non-triviality, the partial characterisation of embeddings, the description of associate spaces in some lim- iting cases and all the results concerning Lorentz-Karamata spaces with the sec- ondary parameter q smaller than one. Those results are, as far as we are aware, new. 1
Optimality of function spaces for classical integral operators
Mihula, Zdeněk ; Pick, Luboš (advisor) ; Vybíral, Jan (referee)
We investigate optimal partnership of rearrangement-invariant Banach func- tion spaces for the Hilbert transform and the Riesz potential. We establish sharp theorems which characterize optimal action of these operators on such spaces. These results enable us to construct optimal domain (i.e. the largest) and op- timal range (i.e. the smallest) partner spaces when the other space is given. We illustrate the obtained results by non-trivial examples involving Generalized Lorentz-Zygmund spaces with broken logarithmic functions. The method is pre- sented in such a way that it should be easily adaptable to other appropriate operators. 1
Weighted inequalities and properties of operators and embeddings on function spaces
Slavíková, Lenka ; Pick, Luboš (advisor) ; Pérez, Carlos (referee) ; Malý, Jan (referee)
The present thesis is devoted to the study of various properties of Banach func- tion spaces, with a particular emphasis on applications in the theory of Sobolev spaces and in harmonic analysis. The thesis consists of four papers. In the first one we investigate higher-order embeddings of Sobolev-type spaces built upon rearrangement-invariant Banach function spaces. In particular, we show that optimal higher-order Sobolev embeddings follow from isoperimetric inequal- ities. In the second paper we focus on the question when the above-mentioned Sobolev-type space is a Banach algebra with respect to a pointwise multiplica- tion of functions. An embedding of the Sobolev space into the space of essentially bounded functions is proved to be the answer to this question in several standard as well as nonstandard situations. The third paper is devoted to the problem of validity of the Lebesgue differentiation theorem in the context of rearrangement- invariant Banach function spaces. We provide a necessary and sufficient condition for the validity of this theorem given in terms of concavity of certain functional depending on the norm in question and we find also alternative characterizations expressed in terms of properties of a maximal operator related to the norm. The object of the final paper is the boundedness of the...
History and current state of recreational mathematics and its relation to serious mathematics
Bártlová, Tereza ; Pick, Luboš (advisor) ; Silva, Jorge Nuno (referee) ; Levy, Doron (referee)
Dissertation abstract The present thesis is devoted to the study of recreational mathematics, with a particular emphasis on its history, its relation to serious mathematics and its educational benefits. The thesis consists of five papers. In the first one we investigate the history of recreational mathematics. We focus on the development of mathematical problems throughout history, and we try to point out the people who had an important influence on the progress of recreational mathematics. The second article is dedicated to Edwin Abbott Abbott and his book called Flatland. It is one of the first popularizing books on geometry. In the third article we review one of the prominent personalities of recreational mathematics, Martin Gardner. The fourth article is in some sense a sequel to the third one. It deals with treachery of mathematical intuition and mathematical April Fool's hoaxes. The last article is devoted to the implementation recreational mathematics to education of students. 1
Weighted rearrangement-invariant spaces and their basic properties
Soudský, Filip ; Pick, Luboš (advisor) ; Soria, Javier (referee) ; Barza, Sorina (referee)
In this thesis we shall provide the reader with results in the field of classical Lorentz spaces. These spaces have been studied since the 50's and have many applications in partial differential equations and interpolation theory. This work includes five papers. First paper studies the properties of Generalized Gamma spaces. Second paper provides an alternative proof of normability characterization of classical Lorentz spaces. The third paper discus conditions of linearity and quasi-norm property of rearrangement-invariant lattices. The following paper gives a characterization of normability of Gamma spaces. And finally the last paper characterizes the embeddings between Generalized Gamma spaces. Powered by TCPDF (www.tcpdf.org)
Behavior of one-dimensional integral operators on function spaces
Buriánková, Eva ; Pick, Luboš (advisor) ; Nekvinda, Aleš (referee)
In this manuscript we study the action of one-dimensional integral operators on rearrangement-invariant Banach function spaces. Our principal goal is to characterize optimal target and optimal domain spaces corresponding to given spaces within the category of rearrangement-invariant Banach function spaces as well as to establish pointwise estimates of the non-increasing rearrangement of a given operator applied on a given function. We apply these general results to proving optimality relations between special rearrangement-invariant spaces. We pay special attention to the Laplace transform, which is a pivotal example of the operators in question. Powered by TCPDF (www.tcpdf.org)

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