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Measure of divergence of possibility measures
Kroupa, Tomáš
Possibility measures are analyzed from the information-theoretic point of view. It is argued for a significant role of Choquet integration theory in this context. The principal result of the paper is the representation theorem for the nonspecificity of a possibility distribution and the new definition of a~measure of divergence of two possibility measures.
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Integral representation theorems in noncompact cases
Kraus, Michal ; Malý, Jan (referee) ; Lukeš, Jaroslav (advisor)
Classical Choquet's theory deals with compact convex subsets of locally convex spaces. This thesis discuss some aspects of generalization of Choquet's theory for a broader class of sets, for example those which are assumed to be only closed and bounded instead of compact. Because Radon measures are usually defined for locally compact topological spaces, and this is not the case of the closed unit ball in a Banach space of infinite dimension, there are used the so called Baire measures in this setting. This thesis particularly deals with the question of existence of resultants of these measures, with the properties of the resultant map, with the analogy of Bauer's characterization of extreme points and with some other concepts known from compact theory. By using some examples we show that many of these theorems doesn't hold in noncompact setting. We also mention forms of these theorems which can be proved.
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Topological and descriptive methods in the theory of function and Banach spaces
Kačena, Miroslav ; Spurný, Jiří (advisor) ; Netuka, Ivan (referee) ; Kalenda, Ondřej (referee)
The thesis consists of four research papers. The first three deal with the Choquet theory of function spaces. In Chapter 1, a theory on products and projective limits of function spaces is developed. It is shown that the product of simplicial spaces is a simplicial space. The stability of the space of maximal measures under continuous affine mappings is studied in Chapter 2. The third chapter employs results from the previous chapters to construct an example of a function space where the abstract Dirichlet problem is not solvable for any class of Baire-n functions with $n\in N$. It is shown that such an example cannot be constructed via the space of harmonic functions. In the final chapter, the recently introduced class of sequentially Right Banach spaces is being investigated. Connections to other isomorphic properties of Banach spaces are established and several characterizations are given.
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Noncommutative Choquet theory
Šišláková, Jana ; Spurný, Jiří (advisor) ; Hamhalter, Jan (referee)
- ABSTRACT - Noncommutative Choquet theory Let S be a linear subspace of a commutative C∗ -algebra C(X) that se- parates points of C(X) and contains identity. Then the closure of the Choquet boundary of the function system S is the Šilov boundary relati- ve to S. In the case of a noncommutative unital C∗ -algebra A, consider S a self-adjoint linear subspace of A that contains identity and generates A. Let us call S operator system. Then the noncommutative formulation of the stated assertion is that the intersection of all boundary representa- tions for S is the Šilov ideal for S. To that end it is sufficient to show that S has sufficiently many boundary representations. In the present work we make for the proof of that this holds for separable operator system.
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Geometric properties of subspaces of continuous functions
Petráček, Petr ; Lukeš, Jaroslav (advisor) ; Netuka, Ivan (referee)
In this thesis we study certain geometric properties of Müntz spa- ces as subspaces of continuous functions. In the first chapter we present some of the most important examples of the Müntz type theorems. Namely, we present the classic Müntz theorem and the Full Müntz theorem in the setting of the space of continuous functions on the interval [0, 1]. We also mention several extensions of these theorems to the case of continuous functions on the general interval [a, b] as well as an analogy of the Full Müntz theorem for the Lp ([0, 1]) spaces. The second chapter is divided into three sections. In the first section we present some definitions and well-known theorems of Choquet theory, which we use to characterize the Choquet boundary of Müntz spa- ces. In the second section we present the result concerning non-reflexivity of Müntz spaces as well as its corollary describing the non-existence of an equiva- lent uniformly convex norm on these spaces. In the third section, we concern ourselves with the question of Müntz spaces having the Radon-Nikodym pro- perty. As a main result of this part we show that a certain type of Müntz spaces doesn't have the Radon-Nikodym property. The final chapter contains a summary of some known results as well as open problems related to the theory of Müntz spaces....
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Some results in convexity and in Banach space theory
Kraus, Michal ; Lukeš, Jaroslav (advisor) ; Kalenda, Ondřej (referee) ; Smith, Richard (referee)
This thesis consists of four research papers. In the first paper we construct nonmetrizable compact convex sets with pathological sets of simpliciality, show- ing that the properties of the set of simpliciality known in the metrizable case do not hold without the assumption of metrizability. In the second paper we construct an example concerning remotal sets, answering thus a question of Martín and Rao, and present a new proof of the fact that in every infinite- dimensional Banach space there exists a closed convex bounded set which is not remotal. The third paper is a study of the relations between polynomials on Banach spaces and linear identities. We investigate under which conditions a linear identity is satisfied only by polynomials, and describe the space of poly- nomials satisfying such linear identity. In the last paper we study the coarse and uniform embeddability between Orlicz sequence spaces. We show that the embeddability between two Orlicz sequence spaces is in most cases determined only by the values of their upper Matuszewska-Orlicz indices. 1
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Toplogical properties of compact convex sets
Kačena, Miroslav ; Lukeš, Jaroslav (referee) ; Spurný, Jiří (advisor)
The first part of the thesis presents the basics of Choquet theory of function spaces needed in the next part. Text deals mainly with general function spaces, the special case of compact convex sets is considered only marginally. The main object of this investigation is an equivalence between simpliciality and some interpolation properties of a function space. The second part is engaged in research on products of function spaces. Various products are defined, the most treated being the multiaffine product. The introductory section focuses just on the connections and differences between these products. The primary goal of the work is a generalization of known results for products of compact convex sets to the context of function spaces. First, extremal sets are examined, the main result is the representation of Choquet boundary of a product space as the product of Choquet boundaries of original spaces. Simplicial spaces are studied next. It is shown, that a product of simplicial spaces is simplicial and in that case established definitions of a product space coincide for affine functions. Finally, maximal measures are investigated.
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Random closed sets
Stroganov, Vladimír ; Honzl, Ondřej (advisor) ; Rataj, Jan (referee)
In this bachelor thesis we are concerned with basic knowledge in random set theory. We define here such terms, as capacity functional, se- lection, measurable and integrable multifunction, Castaing representation and Aumann expectation of random closed set. We present Choquet theo- rem, Himmelberg measurability theorem, theorems of properties of selections and expectation. We present also several examples which illustrate the the- ory. 1
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