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Lebesgue density theorem for Haar measure
Sterzik, Marek ; Simon, Petr (advisor) ; Zahradník, Miloš (referee)
In this work, we study Lebesgue theorem analogy in the space 2k with Haar measure and a related theorem about -k-linkedness of the measure algebra of this space. The whole text is divided in three chapters. In the first chapter we explain some important definitions and basic properties of the measure space. The Lebesgue theorem is studied in the second chapter. After the essential definition of the point of density, the major part of the chapter is dedicated to the proof of the theorem. The theorem states, that the symmetric difference between any measurable set and the set of its points of density has measure zero. In the third chapter we study the -k-linkedness theorem; a theorem which states that the measure algebra of the space 2 is -k-linked, if 2 .
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Riemann zeta function
Čoupek, Petr ; Rokyta, Mirko (advisor) ; Zahradník, Miloš (referee)
Riemann zeta function represents an important tool in analytical number theory with various applications in quantum mechanics, probability theory and statistics. First introduced by Bernhard Riemann in 1859, zeta function is a central object of many outstanding problems. From previous results follows the importance of zeta function for further development in the field of number theory. This thesis provides basic properties of the Riemann zeta function. In particular, we prove theorems concerning the distribution of its roots outside and inside the critical strip which leads to the formulation of the Riemann hypothesis and theorems concerning the irrationality of selected values of the Riemann zeta function including the proof of the irrationality of ζ(3). 1
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Fourier transform of periodic structures
Zajíc, Tomáš ; Zahradník, Miloš (advisor) ; Krýsl, Svatopluk (referee)
Mathematical description of Fourier transform of the periodic structure. We introduce the concept of the Fourier series and we investigate the Dirichlet kernel. We also introduce the concept of distributions, the Fourier transform and convolution. Using this we discover the properties of the Dirac's delta, the Dirac comb and then we define the periodic structure. In conclusion, we mention the dual lattice. The thesis is designed to contain physical notes. Some of proofs are formal.
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Hierarchical solution and the structure of order parameters in the mean-field theory of spin glasses and related materials
Klíč, Antonín ; Janiš, Václav (advisor) ; Zahradník, Miloš (referee) ; Zdeborová, Lenka (referee)
We analyze the replica-symmetry-breaking (RSB) construction in the Sherrington - Kirkpatrick (SK) model and in the p-state Potts glass for p ≤ 4. We present a general scheme for deriving an asymptotic solution with an arbitrary number of discrete hierarchies of broken replica symmetry near the critical temperature for both models, and close to the de Almeida- Thouless instability line in the SK model. We show that in the SK model all solutions with finite many hierarchies are unstable and only the scheme with infinite many hierarchies becomes marginally stable in the spin-glass phase. For the Potts glass, we find, moreover, an one-step RSB solution which co- exists with the infinite RSB solution for p > p∗ ≈ 2.82. The former solution is locally stable but has lower free energy than the latter which is marginally stable and has the highest free energy. 1
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Contour methods in the mathematical theory of phase transitions
Nagy, Oliver ; Zahradník, Miloš (advisor) ; Netočný, Karel (referee)
Title: Contour methods in the mathematical theory of phase transitions Author: Oliver Nagy Department: Department of Mathematical Analysis Supervisor: doc. RNDr. Miloš Zahradník, CSc., Department of Mathematical Analysis Abstract: This thesis concerns itself with three topics, namely polymer models, Pirogov-Sinai theory and one-dimensional Dyson models. It contains a short introduction into all three topics. The introduction to Pirogov-Sinai theory will serve as a starting point for a future expanded introductory exposition, since such a material is missing in the contemporary literature. Research result of the first chapter is a detailed combinatorial analysis of cluster expansion of hard-core repulsive polymer model based on 'self-avoiding polymer trees', leading to simplification of the structure of summation in the partition function. In the case of Dyson models we suggest an alternative definition of contours for the one-dimensional Dyson model with the exponent of polynomially-decaying interaction p ∈ (1, 2) that is usable for study using Pirogov-Sinai methods. Keywords: Contours, polymers, cluster expansion, Pirogov-Sinai theory, Dyson model;
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From asymptotic density to the Riemann zeta-function
Grebík, Jan ; Balcar, Bohuslav (advisor) ; Zahradník, Miloš (referee)
We study the connection of combinatorics of natural numbers and measures extending the asymptotic density with the structures of number theory and the Riemann zeta-function. We show that the study of measures extending density via ultrafilter limits can be restricted to thin ultrafilters and we charac- terize the σ-additivity of such measures using the ∗invariance of ultrafilters. We study the generic extension obtained by forcing with the algebra P(N) modulo the density ideal. We show that this is a two-step iteration, where the first step is the known forcing with P(N)/fin adding a selective ultrafilter, while the second step kills the selectivity. We isolate the values of some cardinal invariants in this extension.
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Fourier transform of periodic structures
Zajíc, Tomáš ; Zahradník, Miloš (advisor) ; Krýsl, Svatopluk (referee)
Mathematical description of Fourier transform of the periodic structure. We introduce the concept of the Fourier series and we investigate the Dirichlet kernel. We also introduce the concept of distributions, the Fourier transform and convolution. Using this we discover the properties of the Dirac's delta, the Dirac comb and then we define the periodic structure. In conclusion, we mention the dual lattice. The thesis is designed to contain physical notes. Some of proofs are formal.
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Hierarchical solution and the structure of order parameters in the mean-field theory of spin glasses and related materials
Klíč, Antonín ; Janiš, Václav (advisor) ; Zahradník, Miloš (referee) ; Zdeborová, Lenka (referee)
We analyze the replica-symmetry-breaking (RSB) construction in the Sherrington - Kirkpatrick (SK) model and in the p-state Potts glass for p ≤ 4. We present a general scheme for deriving an asymptotic solution with an arbitrary number of discrete hierarchies of broken replica symmetry near the critical temperature for both models, and close to the de Almeida- Thouless instability line in the SK model. We show that in the SK model all solutions with finite many hierarchies are unstable and only the scheme with infinite many hierarchies becomes marginally stable in the spin-glass phase. For the Potts glass, we find, moreover, an one-step RSB solution which co- exists with the infinite RSB solution for p > p∗ ≈ 2.82. The former solution is locally stable but has lower free energy than the latter which is marginally stable and has the highest free energy. 1
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