Browsing Doctoral Dissertations by Title
-
Vasić, Velimir (Belgrade)[more][less]
-
Berisha, Fevzi (Priština)[more][less]
-
Komljenović, Stevo (Belgrade , 1964)[more][less]
-
Perić, Milan (Beograd , 2021)[more][less]
Abstract: his thesis presents a method for calculating the polynomial entropy of the topolog-ical dynamic system with finitely many non-wandering points. A special coding is adapted forsuch systems. Thanks to this coding the polynomial entropy can be bounded by the numberof specific mutually singular points in the closures of stable manifolds of non-wandering points.This method was applied to Morse gradient systems. It is shown that the polynomial entropyof the Morse gradient system is bounded byn(F) URI: http://hdl.handle.net/123456789/5215 Files in this item: 1
Milan_Peric_disertacija.pdf ( 731.8Kb ) -
Ivković, Stefan (Beograd , 2021)[more][less]
Abstract: In the first part of the thesis, we establish the semi-Fredholm theory on Hilbert C∗- modules as a continuation of the Fredholm theory on Hilbert C∗-modules which was introduced by Mishchenko and Fomenko. Starting from their definition of C∗-Fredholm operator, we give definition of semi-C∗-Fredholm operator and prove that these operators correspond to one-sided invertible elements in the Calkin algebra. Also, we give definition of semi-C∗-Weyl operators and semi-C∗-B-Fredholm operators and obtain in this connection several results generalizing the counterparts from the classical semi-Fredholm theory on Hilbert spaces. Finally, we consider closed range operators on Hilbert C∗-modules and give necessary and sufficient conditions for a composition of two closed range C∗-operators to have closed image. The second part of the thesis is devoted to the generalized spectral theory of operators on Hilbert C∗-modules. We introduce generalized spectra in C∗-algebras of C∗-operators and give description of such spectra of shift operators, unitary, self-adjoint and normal operators on the standard Hilbert C∗- module. Then we proceed further by studying generalized Fredholm spectra (in C∗-algebras) of operators on Hilbert C∗-modules induced by various subclasses of semi-C∗-Fredholm operators. In this setting we obtain generalizations of some of the results from the classical spectral semi-Fredholm theory such as the results by Zemanek regarding the relationship between the spectra of an operator and the spectra of its compressions. Also, we study 2×2 upper triangular operator matrices acting on the direct sum of two standard Hilbert C∗-modules and describe the relationship between semi-C∗-Fredholmness of these matrices and of their diagonal entries. URI: http://hdl.handle.net/123456789/5305 Files in this item: 1
Stefan_Ivkovic_Doktorska_disertacija.pdf ( 1.505Mb ) -
Živanović, Žarko (Belgrade , 1974)[more][less]
-
Ćirić, Ljubomir (Belgrade)[more][less]
-
Dostanić, Milutin (Belgrade , 1984)[more][less]
-
Uksanović, Jovan (Belgrade)[more][less]
-
Malkov, Saša (Belgrade)[more][less]
-
Carić, Marko (Beograd , 2023)[more][less]
Abstract: This dissertation discusses the problem of calculating the number of equivalent classes of a Boolean function. The difficulty of determining the number of equivalence classes increases sharply with the number of variables sn. The motivation for choosing this topic lies in the fact that concrete numbers have been known so far only for relatively small values of n, although the problem itself has long been theoretically solved. Let G be the permutation group of the set Bn={0,1}n. Effect of Gonscalar group, Bn→B1, that is, vector invertible Boolean functions, Bn→Bn. Two scalar Boolean functions f(k)ig(k), defined by Bn, are considered equivalent. ∈G forever ∈Bnf(k )=g(σ(k)) holds. Two vector invertible Boolean functions f(k) and g(k) are considered equivalent in relation to the group G, i.e. ))).The equivalence relation∼decomposes the sets of all Boolean functions into equivalence classes.The equivalence of Boolean functions confers significant applications in the logical synthesis of combinatorial circuits and cryptography, especially in connection with the design of S-boxes. Let Un(G) and Vn(G) denote the number of scalar equivalence classes, ie. vector invertible Boolean functions of n variables with respect to the group G. The numbers Un(G) and Vn(G) can be calculated relatively simply if the cycle index from the group G to the G group is known. Induced by the group Snpermutations of coordinate elements step = (k1,k2,...,kn)∈Bn, •group Gn, induced by permutations and additions of coordinates, •group GLnlinear invertible transformations of elements of vector space Bn, and •group AGLof invertible transformations of elements Bn. If the permutation σ∈Ghasikcycles of lengthk1, its cycle structure is(σ)=(i1,i2,...).The cyclic index of the groupGisgeneratrix ZG(f1,f2,...)=1 |G|σ∈Gk1 fik k structure cycles σene structures of cycles σfraconstructionsGsides ∗pressuresGpermutations of the red group are known, but the cycle indexes itself, i.e. numbers Un(G) and Vn(G), are practically calculated only for relatively small values, for example n10. The dissertation presents original results in the field of enumeration of equivalence classes of Boolean functions in relation to these four groups of soft transformations. A similar expression is derived for all four groups of soft transformations for the cycle index in the form of the sumover partition softhennumbern. Based on the precyclical index much more. An overview of known results for relatively small and new results in the thesis for larger ones are shown in the following table: Number\GSnGnGLnAGLn Un(G)11→3310→328→3110→31 Vn(G)6→307→276→266, participates in direct effect, by special effect 26 latingthenumberofequivalenceclassesthatdoesnotuseacycleindex is shown and described in the third paper from the introductory chapter. These second parts of the dissertation refer to monotone Boolean functions — scalar Boolean functions that satisfy the condition of monotonicity (from which follows f(k)f(i)). Letrn, i.e. monotoneBooleanfunctionsofnvariables. The difficulty of calculating the number rn increases rapidly with n, so that until recently the last term of the sequence to be calculated was r7. The procedure described in the dissertation is based on Frobenius' theorem, on the basis of which the number r8 was determined. The dissertation consists of the first introductory chapter and the following three chapters. In the second chapter, theoretical concepts related to the material from chapters 3 and 4 are introduced, and they relate to discrete mathematics, combinatorics and the index of the cycle considered by the soft cycle of the 3rd form for describing the 3rd cycle. indices for the four considered groups of permutations, as well as the numbers Un(G) and Vn(G) of the equivalent class of the Boolean function with respect to these groups. First, the common improvements for all four groups are discussed, and then the specific accelerations related to individual groups are published by group. ter. In Chapter 4, the problem of finding the number of equivalence classes of a monotone Boolean function is solved. First, a general expression for calculating a number is given based on the Frobenius theorem of the form of the sum (by the soft number partition of the number) of the number from the fixed part of the graph corresponding to the point corresponding to the point. In different partitions, different ways of calculating the number of non-fixed points for n8 are shown. The procedure based on which the number r8 was calculated, which also represents the original contribution of this dissertation, is shown in the first paper from the list from pp. 1 to 3. practically at the same time the obtained result described in the dissertation. URI: http://hdl.handle.net/123456789/5571 Files in this item: 1
MarkoCaricDisertacija.pdf ( 1.467Mb ) -
Maljković, Mirjana (Beograd , 2021)[more][less]
Abstract: Proteins are linear biological polymers composed of amino acids whose structure and function are determined by the number and order of amino acids. The structure of the protein has three levels: primary, secondary and ter- tiary (three-dimensional, 3D) structure. Since the experimental determination of protein 3D structure is expensive and time-consuming, it is important to develop predictors of protein 3D structure properties from the amino acid sequence (pri- mary structure), such as 3D structure of the protein backbone. The 3D structure of the backbone can be described using prototypes of local protein structure, i.e. prototypes of protein fragments with a length of few amino acids. A set of local structure prototypes determines the library of local protein structures, also called the structural alphabet. A structural alphabet is defined as a set of N proto- types of L amino acid length. The subject of this dissertation is the development of models for the prediction of structural alphabet prototypes for a given amino acid sequence using different data mining approaches. As one of the most known, structural alphabet Protein Blocks (PBs) was used in one part of the doctorial re- search. Structural alphabet PBs consists of 16 prototypes that are defined using fragments of 5 consecutive amino acids. The amino acid sequence is combined with the structural properties of a protein that can be determined based on amino acid sequence (occurrence of repeats in the amino acid sequence) and results of predictors of protein structural properties (backbone angles, secondary structures, occurrence of disordered regions, accessible surface area of amino acids) as an input to the prediction model of structural alphabet prototypes. Besides the de- velopment of models for prediction of prototypes of existing structural alphabet, the analysis of the capability of developing new structural alphabets is researched by applying the TwoStep clustering algorithm and construction of models for the prediction of prototypes of new structural alphabets. Several structural alpha- bets, which differ in the length of prototypes and the number of prototypes, have been constructed and analyzed. Fragments of the large number of proteins, whose structure is experimentally determined, were used to construct the new structural alphabets. URI: http://hdl.handle.net/123456789/5236 Files in this item: 1
dthesis.Matf.Mirjana.Maljkovic.pdf ( 47.43Mb ) -
Milogradov-Turin, Jelena (Belgrade)[more][less]
URI: http://hdl.handle.net/123456789/126 Files in this item: 1
phdJelenaMilogradovTurin.pdf ( 115.3Mb ) -
Babanić, Mirko (Beograd , 2022)[more][less]
Abstract: The preparatory part of the dissertation, which leads to the basic one, is based on return-variance parameters that represent two key random variables of the model devised by Markowitz. The research used historical data that in themselves reflect all available information absorbed by the financial market, and therefore, we can consider them not only homogeneous but also absolute (for reasons of realization). Therefore, an analytical procedure of approximation by a sixth-degree polynomial was performed on such data, which represent combinations of values of average returns and variances of portfolio returns, thus establishing a relation that is explicitly expressed by an algebraic sixth-degree polynomial equation. After that, further analytical procedure determined the conditions for the existence of both the minimum and the tangent portfolio and redefined the terms: efficient portfolio set, preference toward risk, risk aversion, and indifference line. The central topic of the dissertation, the revision of Tobin 's separation theorem, is formulated and proved through three theorems, one basic and two auxiliary. URI: http://hdl.handle.net/123456789/5593 Files in this item: 1
Mirko Babanic - Disertacija.pdf ( 1.504Mb ) -
Stamatović, Biljana (Beograd , 1999)[more][less]
-
Jelić, Milena (Belgrade)[more][less]
-
Milovanović - Aranđelović, Marina (Beograd , 2016)[more][less]
Abstract: The aim of this dissertation is to present new properties of some classes of contractive mappings, and applications of this results to nonlinear analysis. It contain six chapters. The first chapter gives basic properties of semi-metric spaces. New result is extension of Borel - Lebesque theorem to semi metric spaces. The second chapter contain generalization of Niemytzki’s fixed point theorem. In third chapter the notion of measure of non-compactness are extended to class of semimetric spaces. New fixed point theorem for condensing mappings defined on semi-metric spaces is presented. Further three chapters contains new common fixed points theorems of Mair - Keeler type, new results for accretive mappings and new common fixed point results for mappings defined on probabilistic metric spaces. URI: http://hdl.handle.net/123456789/4482 Files in this item: 1
DisertacijaMilovanovic-Arandjelovic_Marina.pdf ( 1.599Mb ) -
Živković, Miodrag (Belgrade , 1990)[more][less]
-
Ivanović, Lav (Belgrade , 1983)[more][less]
-
Bulatović, Ranislav (Belgrade , 1983)[more][less]