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Spaces of continuous functions with the pointwise topology
Slavata, Martin ; Spurný, Jiří (advisor) ; Kalenda, Ondřej (referee)
Title: Spaces of continuous functions with the pointwise topology Author: Martin Slavata Department: Department of Mathematical Analysis Supervisor: doc. RNDr. Jiří Spurný, Ph.D. Supervisor's e-mail address: Jiri.Spurny@mff.cuni.cz Abstract: This thesis describes properties of spaces of continuous functions with the topology of pointwise convergence. Emphasis is put on characterizations of compact subsets of such spaces and on compactness of the spaces themselves. The thesis describes properties of the class of angelic spaces (notion by Fremlin) and shows when spaces of continuous functions with pointwise topology belong to this class (result by J. Orihuela). Thus a generalization of a theorem of Grothendieck is obtained. Also a limitation of the class of angelic spaces is shown - it is not closed under topological product. This leads to the next topic of the thesis, the class of strictly angelic spaces (introduced by W. Govaerts) and its intersection with the class of spaces of continuous functions with pointwise topology. In the end the thesis shows under which conditions the space of continuous functions satisfies the definition of the respective notions related to compactness. Keywords: spaces of continuous functions; pointwise convergence; compactness; angelicity
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Perfect functions of the first Baire class
Skovajsa, Břetislav ; Spurný, Jiří (advisor) ; Zajíček, Luděk (referee)
A wide class of problems in mathematical analysis can be described as searching for properties P such that for each F from a given system of mappings F between spaces K and L an arbitrary real valued function on L has the property P if and only if its composition with F also has this property. The inspiration for this text comes from [1], where the mentioned problem is examined in the form of stability of Baire classes of functions towards composition with a continuous mapping between compact topological spaces. The goal of this text will be to get acquainted with the original result, to slightly improve it on compact metric spaces, then to take a closer look at the finer structure of B1 functions and to try to find a similar kind of stability in this environment. [1] J. Lukeš, J. Malý, I. Netuka, J. Spurný, Integral representation theory: ap- plications to convexity, Banach spaces and potential theory, Walter de Gruyter (2010).
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Limit behavior of the Nash equlibrium
Kovařík, Vojtěch ; Spurný, Jiří (advisor) ; Bárta, Tomáš (referee)
The subject of study of game theory - games - serves as mathematical models for real-life problems. In every game there are two or more players who aim to maximize their own profit by choosing their actions. A situation where no player can benefit from changing his own action alone has got particular importance in the study of games - it is called Nash equilibrium. Games with a finite number of players have certain advantages over those with an infinite number of players. For one, problems whose model is a game with a finite number of players are quite common. Moreover, one of the classical results of game theory is that (with certain additional assumptions) in every game with a finite number of players there exists a Nash equilibrium. On the other hand, when trying to describe the properties of a game with an infinite number of players we might be able to use calculus instead of going trough all possibilities (as is common for games with a finite number of players), which tends to be computationally demanding. However, if we want to use these advantages of games with an infinite number of players, it is important first to know whether there is any relationship between games with a finite and infinite number of players at all. The goal of this thesis is to define terms and to introduce tools which would allow...
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Skorokompaktní vnoření prostorů funkcí
Křepela, Martin ; Pick, Luboš (advisor) ; Spurný, Jiří (referee)
This work is dealing with almost-compact embeddings of function spaces, in particular, the class of classical and weak Lorentz spaces with a norm given by a general weight fuction is studied. These spaces are not Banach function spaces in general, thus the almost-compact em- bedding is defined for more general sturctures of rearrangement-invariant lattices. A general characterization of when an r.i. lattice is almost-compactly embedded into a Lorentz space, involving an optimal constant of a certain continuous embedding, is proved. Based on this the- orem and appropriate known results about continuous embeddings, explicit characterizations of mutual almost-compact embeddings of all subtypes of Lorentz spaces are obtained. 1
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Quantitative weak compactness
Rolínek, Michal ; Spurný, Jiří (advisor) ; Kalenda, Ondřej (referee)
In this thesis we study quantitative weak compactness in spaces (C(K), τp) and later in Banach spaces. In the first chapter we introduce several quantities, which in different manners measure τp-noncompactness of a given uniformly bounded set H ⊂ RK . We apply the results in Banach spaces in chapter 2, where we prove (among others) a quantitative version of the Eberlein-Smulyan theorem. In the third chapter we focus on convex closures and how they affect measures of noncompactness. We prove a quantitative version of the Krein-Smulyan theorem. The first three chapters show that measuring noncompactness is intimately related to measuring distances from function spaces. We follow this idea in chapters 4 and 5, where we measure distances from Baire one functions first in RK and later also in Banach spaces. 1
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Radon-Nikodým compact spaces
Cepák, Jiří ; Spurný, Jiří (advisor) ; Holický, Petr (referee)
In the present work we study Radon-Nikodým compact spaces (RN compacta for short) their topological characterizations and properties with emphasis on those related to the problem of continuous image of RN compact. First chapter consists of auxiliary results. In second chapter we give eight characterizations of RN compacta as well as several examples. In third chapter we introduce three notions weaker than that of RN compact and stable under continuous images and we show that they are equivalent. Last chapter is devoted to partial positive solutions to the problem of continuous image.
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Properties of Poulsen simplices
Jaroň, Zdeněk ; Spurný, Jiří (advisor) ; Kurka, Ondřej (referee)
Title: Properties of Poulsen simplices Author: Zdeněk Jaroň Department: Department of Mathematical Analysis Supervisor: Doc. RNDr. Jiří Spurný, Ph.D. Abstract: In the present thesis, we study a generalisation of concept of the Poulsen simplex in general, non-metrizable case. First, for any given simplex F we con- struct a new one S, containing F as a face, having dense set of extreme points and preserving some important properties of F. In the next part, we employ this con- struction to build up, for any given infinite cardinal κ, two simplices S1, S2 with dense extreme boundary, with density character equal to κ and with spaces of affine functions Ac (S1) and Ac (S2) having the same density character, but which are not affinely homeomorphic. Keywords: Poulsen simplex, projective limit, Helly space
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