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Disintegration of category in the sense of the Kuratowski-Ulam theorem
Rondoš, Jakub ; Spurný, Jiří (advisor) ; Holický, Petr (referee)
The Fubini theorem and the Kuratowski-Ulam theorem show similarities be- tween the concepts meager set in Polish space and set of zero measure in standard Borel space. Those theorems can be generalized. The Fubini theorem is generali- zed by the Measure disintegration theorem and the Kuratowski-Ulam theorem is generalized by the Category disintegration theorem. The claims of disintegration theorems are analogous and show even more the similarities between meager sets and sets of zero measure. The main aim of this thesis is to prove disintegration theorems and show how Fubini and Kuratowski-Ulam theorems follow. 1
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Exceptional Sets in Mathematical Analysis
Rmoutil, Martin ; Kalenda, Ondřej (advisor) ; Holický, Petr (referee) ; Zindulka, Ondřej (referee)
Title: Exceptional Sets in Mathematical Analysis Author: Martin Rmoutil Department: Department of Mathematical Analysis Supervisor: Doc. RNDr. Ondřej Kalenda, Ph.D., DSc., Department of Mathematical Analysis Abstract: The present thesis consists of four research articles. In the first paper we study the notion of σ-lower porous set; our main result is the existence of two closed sets A, B ⊂ R which are not σ-lower porous, but their product in R2 is lower porous. In the second and third article we use a set-theoretical method of el- ementary submodels involving the Lwenheim-Skolem theorem to prove that certain σ-ideals of sets in Banach spaces are separably determined. In the second article we do so for σ-porous sets and σ-lower porous sets. In the next article we refine these methods obtaining separable determination of a wide class of σ-ideals. In both cases we derive interesting corollaries which extend known theorems in separable spaces to the nonseparable setting; for example, we obtain the following theorem. Any continuous convex function on an Asplund space is Frchet differentiable outside a cone small set. In the fourth article we introduce the following notion. A closed set A ⊂ Rd is said to be c-removable if the following is true: Every real function on Rd is convex whenever it is continuous on Rd...
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Gradient mapping of functions of several variables
Skálová, Alena ; Zelený, Miroslav (advisor) ; Holický, Petr (referee)
Title: Gradient mapping of functions of several variables Author: Alena Skálová Department: Department of Mathematical Analysis Supervisor: doc. RNDr. Miroslav Zelený, Ph.D., Department of Mathematical Analysis Abstract: In the thesis we prove that the following statement holds true. For each d ≥ 2, for each open bounded set U ⊂ Rd and for each set F ⊂ Rd of the Borel class Fσ there exists an everywhere differentiable function u: Rd → R such that ∇u(x) ∈ U for all x ∈ Rd , ∇u(x) ∈ U for all x ∈ F, ∇u(x) ∈ ∂U for λd-almost all x ∈ Rd \ F.
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Modifications of Whitney's $C^1$ extension theorem.
Dovhoruk, Olesya ; Zajíček, Luděk (advisor) ; Holický, Petr (referee)
Title: Modifications of Whitney's C1 extension theorem. Author: Olesya Dovhoruk Department: Department of Mathematical Analysis Supervisor: prof. RNDr. Luděk Zajíček, DrSc., Department of Mathematical Ana- lysis Abstract: This work deals with modifications of the Whitney's C1 extension theorem on a special closed set M in Rn . The work investigates of whether it is possible to skip some of the assumptions of the Whitney's theorem. It turns out that if we do not assume the continuity of a function f : M → R, which is being extended from a general closed set M ⊂ Rn , then f is continuous from the remaining assumptions in the Whitney's theorem, but if we skip the continuity of a function d, which features in the Whitney's theorem (and plays a role of the generalised differential of the function f), then d is continuous from the remaining assumptions, but just for n = 1. Further, some proposals based on modifications of the assumptions of the Whit- ney's theorem are proved. For instance, the theorem of an existence of a C1 extension of a function f : (a, b)×[0, c), f ∈ C1 ((a, b)×(0, c)), for which is valid that the function gradf has finite limits in (a, b) × {0}. Another similar result of the work is the existence of a C1 extension of a function f : M ⊂ Rn → R, where M = M◦ = ∅ is a compact and convex set and...
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Applications of descriptive set theory in mathematical analysis
Doležal, Martin ; Zelený, Miroslav (advisor) ; Holický, Petr (referee) ; Zapletal, Jindřich (referee)
We characterize various types of σ-porosity via an infinite game in terms of winning strategies. We use a modification of the game to prove and reprove some new and older in- scribing theorems for σ-ideals of σ-porous type in locally compact metric spaces. We show that there exists a closed set which is σ-(1 − ε)-symmetrically porous for every 0 < ε < 1 but which is not σ-1-symmetrically porous. Next, we prove that the realizable by an action unitary representations of a finite abelian group Γ on an infinite-dimensional complex Hilbert space H form a comeager set in Rep(Γ, H). 1
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Properties of Cantor function
Fiala, Martin ; Hencl, Stanislav (advisor) ; Holický, Petr (referee)
Properties of Cantor function Author: Martin Fiala Supervisor: Stanislav Hencl Abstract: In the present thesis we study main properties of the Can- tor function (sometimes called Cantor Devil's staircase in popular lit- erature), named after significant german mathematician Georg Cantor ( 3 March 1845 in St Petersburg, 6 Jan 1918 in Halle). 1
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Generalized limits of affine functions
Holub, Aleš ; Spurný, Jiří (advisor) ; Holický, Petr (referee)
We construct a co-analytic filter on the set of finite sequences of natural numbers, which allows us to obtain a strongly affine function of arbitrary Borel class from compact convex subset of locally convex space through single limit process (by this filter) applied to countable system of affine continuous functions. Conversely we show that function obtainted as result of such process is necessarily Borel and strongly affine. Further we generalize this method using metrizable reduction approach for Baire functions on non-metrizable spaces. Last chapter covers similar result for bi-analytic functions on separable metrizable spaces.
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Collections of compact sets in descriptive set theory
Vlasák, Václav ; Zelený, Miroslav (advisor) ; Holický, Petr (referee) ; Tišer, Jaroslav (referee)
1 Title: Collections of compact sets in descriptive set theory Author: Václav Vlasák Department: Department of Mathematical Analysis Supervisor: Doc. RNDr. Miroslav Zelený, Ph.D. Author's e-mail address: vlasakmm@volny.cz Abstract: This work consists of three articles. In Chapter 2, we dissert on the connections between complexity of a function f from a Polish space X to a Polish space Y and complexity of the set C(f) = {K ∈ K(X); f K is continuous}, where K(X) denotes the space of all compact subsets of X equipped with the Vietoris topology. We prove that if C(f) is analytic, then f is Borel; and assuming ∆1 2-Determinacy we show that f is Borel if and only if C(f) is coanalytic. Similar results for projective classes are also presented. In Chapter 3, we continue in our investigation of collection C(f) and also study its restriction on convergent sequences (C(f)). We prove that C(f) is Borel if and only if f is Borel. Similar results for projective classes are also presented. The Chapter 4 disserts on HN -sets, which form an important subclass of the class of sets of uniqueness for trigonometric series. We investigate the size of these classes which is reflected by the family of measures called polar which annihilate all the sets belonging to the given class. The main aim of this chapter is to answer in...
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New measures of weak non-compactness
Bendová, Hana ; Kalenda, Ondřej (advisor) ; Holický, Petr (referee)
The main topic of this thesis is the measures of weak non-compactness, which, in different ways, measure weak non-compactness of bounded sets in Banach spa- ces. Besides some known measures of weak non-compactness, we introduce new measures, that are more natural in some sense, and we show the relationships be- tween them. We prove quantitative versions of Eberlein-Grothendieck, Eberlein- Šmulian, and James' theorems. Afterwards, we deal with measures of weak non-compactness of the unit ball and measures of weak non-compactness of sets in Banach spaces with w∗ -angelic dual unit ball. We prove that in these cases some of the defined measures coincide. Finally, we focus on the behaviour of the defined measures while passing to convex and absolute convex hull. We prove quantitative version of Krein's theorem and we also prove that most of the mea- sures do not change when passing to convex and absolute convex hull in Banach spaces with w∗ -angelic dual unit ball.
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