This thesis is focused on the problem of growth and integrability in multi-valued dynamics generated by $SL_2 (\mathbb{Z})$ actions. An important example is given by Markov dynamics on the cubic surface $$x^2+ y^2 +z^2 = 3xyz,$$ generating all the integer solutions of this celebrated Diophantine equation, known as Markov triples. To study the growth problem of Markov numbers we use the binary tree representation. This allows us to define the Lyapunov exponents $\Lambda (x)$ as the function of the paths on this tree, labelled by $x \in \mathbb{R}P^1$. We prove that $\Lambda (x)$ is a $PGL_2 (\mathbb{Z})$-invariant function, which is zero almost everywhere but takes all values in $\left[ 0, \ln \varphi \right]$ (where $\varphi$ denotes the golden ratio). We also show that this function is monotonic, and that its restriction to the Markov-Hurwitz set of most irrational numbers is convex in the Farey parametrisation. We also study the growth problem for integer binary quadratic forms using Conway's topograph representation. It is proven that the corresponding Lyapunov exponent $\Lambda_Q(x) = 2 \Lambda(x)$ except for the paths along the Conway river. Finally, we study the tropical version of the Markov dynamics on the tropical version of the Cayley cubic proposed by Adler and Veselov, and show that it is semi-conjugated to the standard action of $SL_2(\mathbb{Z})$ on a torus. This implies the dynamics is ergodic, with the Lyapunov exponent and entropy given by the logarithm of the spectral radius of the corresponding matrix.

Στην εργασία αυτή παρουσιάζονται τα βασικά στοιχεία της θεωρίας των συνεχιζόμενων κλασμάτων και στη συνέχεια αναπτύσσονται οι αλγόριθμοι που επιτρέπουν την εκτέλεση πράξεων μεταξύ συνεχιζόμενων κλασμάτων και ρητών αριθμώ,αλλά και μεταξύ συνεχιζόμενων κλασμάτων. / In this thesis we describe the basic theory of continued fractions and describe the algorithms that enable us to perform arithmetic operations with continued fractions and rational numbers,as well as with continued fractions.

The “infrastructure” of quadratic fields is a body of theory developed by Dan Shanks, Richard Mollin and others, in which they relate “reduced ideals” in the rings and sub-rings of integers in quadratic fields with periodicity in continued fraction expansions of quadratic numbers. In this thesis, we develop cubic analogs for several infrastructure theorems. We work in the field K=Q(), where 3=m for some square-free integer m, not congruent to ±1, modulo 9. First, we generalize the definition of a reduced ideal so that it applies to K, or to any number field. Then we show that K has only finitely many reduced ideals, and provide an algorithm for listing them. Next, we define a sequence based on the number alpha that is periodic and corresponds to the finite set of reduced principal ideals in K. Using this rudimentary infrastructure, we are able to establish results about fundamental units and reduced ideals for some classes of pure cubic fields. We also introduce an application to Diophantine approximation, in which we present a 2-dimensional analog of the Lagrange value of a badly approximable number, and calculate some examples.

Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-06-12T20:44:03Z No. of bitstreams: 1 SebastiaoAlvesSilva.pdf: 1093667 bytes, checksum: 7d7111ace431e2e93ddfa2af4ec78c6c (MD5) / Made available in DSpace on 2017-06-12T20:44:03Z (GMT). No. of bitstreams: 1 SebastiaoAlvesSilva.pdf: 1093667 bytes, checksum: 7d7111ace431e2e93ddfa2af4ec78c6c (MD5) Previous issue date: 2016-09-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / In this work we make a presentation on continued fractions, from its intuitive historical origin, along with the evolution and maturation of their concept to get your formal mathematical definition. We use continued fractions to represent the real numbers, sort irrational numbers, as well as some of its applications in solving problems ranging from real numbers approximations by rational numbers, solving linear Diophantine equations in two variables, calculation of numerical roots resolution exponential and logarithmic equations, solving geometry problems. In addition, we present what we consider to be classic problems solved by continued fractions, they are: construction of gears, analysis of lunar eclipses, and analysis of construction schedules. / Neste trabalho fazemos uma apresentação sobre frações contínuas, desde sua origem histórica intuitiva, juntamente com a evolução e maturação de seu conceito até chegar a sua definição matemática formal. Utilizamos frações contínuas para representar os números reais, classificar números irracionais, bem como algumas de suas aplicações na resolução de problemas, que vão de aproximações de números reais por números racionais, resolução de equações diofantinas lineares de duas variáveis, cálculo de raízes numéricas, resolução de equações exponenciais e logarítmicas, resolução de problemas de Geometria. Além disso, apresentamos o que consideramos serem problemas clássicos resolvidos por fações contínuas, são eles: construção de engrenagens, análises de eclipses lunares, e análise da construção de calendários.

Made available in DSpace on 2014-06-11T19:26:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-19Bitstream added on 2014-06-13T20:27:27Z : No. of bitstreams: 1 lima_maf_me_sjrp.pdf: 528569 bytes, checksum: 3cad2d8f7175d945b2ead7fb45a5c4e1 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O principal objetivo deste trabalho é estudar métodos para construir os numeradores e denominadores parciais da fração contínua que corresponde a duas expansões em série de potências de uma função analítica f(z); em z =0 e em z = 00. / The main purpose of this work is to two series expansions of an analytic function f(z); in z =0 and z =00 simultaneously. Furthermore we considered the case when there are zero coefficients in the series and also whwn there is symmetry in the coefficients of the two series. Some examples are given.

De nombreux chercheurs se sont intéressés à la Combinatoire des mots aussi bien d'un point de vue théorique que pratique. Pendant plus de $100$ ans de recherche, de nombreuses familles de mots ont été découvertes, certaines sont infinies et d'autres sont finies. Dans cette thèse, on s'intéresse aux mots de Christoffel. On aborde aussi les mots de Lyndon et les mots Strumians standards. Dans cette thèse, nous donnons de nombreuses propriétés sur les mots de Christoffel et on approfondit l'étude de la notion d'équilibre. Il est connu que les mots de Christoffel sont des mots équilibrés sur un alphabet binaire et sont formés par la discrétisation de segments de droite de pente rationnelle. Les mots de Christoffel sont aussi retrouvés dans l'étude de la synchronisation de k processus dirigé par k mots équilibrés. Pour k=2, on retombe sur les mots de Christoffel, tandis que pour k>2, la situation est plus compliquée et nous amène à la conjecture de Fraenkel qui est ouverte depuis plus de 40 ans. Comme c'est difficile d'atteindre cette conjecture, alors nous avons cherché à construire des outils qui nous aide à s'approcher de cette conjecture. On introduit ainsi la matrice d'équilibre B_w où w est un mot de Christoffel et la valeur maximale de cette matrice est l'ordre d'équilibre du mot binaire utilisé. Comme les mots de Christoffel sont équilibrés alors la valeur maximale dans ce cas là sera égale à 1 et chaque ligne de cette matrice sera formée des mots binaires. Cela nous pousse à tester de nouveau l'ordre d'équilibre de chaque mot obtenu et une nouvelle matrice est obtenue qui s'appelle matrice d'équilibre du second ordre . Cette matrice admet de plusieurs propriétés et de symétries et a une forme particulière comme on est capable de la partager en $9$ blocs où c'est suffisant de savoir 3 parmi eux pour construire le reste. Ces trois blocs correspondent à des matrices de mots de Christoffel qui se trouvent dans des niveaux plus proches de la racine de l'arbre des mots de Christoffel. La valeur maximale de cette nouvelle matrice U_w est appelée équilibre du second ordre. En regardant les chemins qui minimisent cette valeur tout au long de l'arbre, on remarque que le chemin suivi par les fractions obtenues du rapport des nombres consécutifs de la suite de Fibonacci, appelé chemin de Zig-zag est l'un des chemins minimaux. On retrouve ces chemins géométriquement sur le chemin de Christoffel en introduisant une nouvelle factorisation pour les mots de Christoffel appelée la factorisation standard symétrique. Nous avons, également, pu trouver une relation directe entre la matrice U_w et le mot de Christoffel initial sans passer par la matrice B_w et cela en étudiant l'ensemble des vecteurs abéliens associés. Tout ce travail nous a permis de réfléchir au sujet initial qui est la synchronisation de k mots équilibrés. Ainsi, pour le cas de 3 générateurs, nous avons pu étudier tous les cas possibles de la synchronisation et une discussion bien détaillée est faite en utilisant un nouvel élément appelé la graine qui est la première colonne de la matrice de synchronisation. La matrice du second ordre d'équilibre, avec toutes ses propriétés va être un bon outil pour étudier la synchronisation de k générateurs et cela constitut mon projet de recherche dans le futur. Nous avons aussi utilisé toutes nos connaissances autour des mots de Christoffel pour avancer dans la reconstruction de polyominoes convexes. Comme le contour d'un tel polyomino est formé des mots de Christoffel de pentes décroissantes, on a introduit un nouvel opérateur qui modifie ce chemin tout en gardant la décroissance des pentes c'est-à-dire en conservant la convexité qui est un premier pas vers la reconstruction. / Many researchers have been interested in studying Combinatorics on Words in theoretical andpractical points of view. Many families of words appeared during these years of research some ofthem are infinite and others are finite. In this thesis, we are interested in Christoffel words andwe introduce the Lyndon words and Standard sturmian words. We give numerous properties forthis type of words and we stress on the main one which is the order of balancedness. Well, itis known that Christoffel words are balanced words on two letters alphabet, where these wordsare exactly the discretization of line segments of rational slope. Christoffel words are consideredalso in the topic of synchronization of k process by a word on a k letter alphabet with a balanceproperty in each letter. For k = 2, we retrieve the usual Christoffel words. While for k > 2, thesituation is more complicated and lead to the Fraenkel’s conjecture that is an open conjecturefor more than 40 years. Since it is not easy to solve this conjecture, we were interested in findingsome tools that get us close to this conjecture. A balance matrix B w is introduced, where wis a Christoffel word, and the maximal value of this matrix is the order of balancedness of thebinary word. Since Christoffel words are one balanced then the maximal value obtained in thismatrix is equal to 1 and all the rows of this matrix is made of binary words. Testing again thebalancedness of these rows, a new matrix arises, called second order balance matrix. This matrixhas lot of characteristics and many symmetries and specially the way it is constructed since it ismade of 9 blocks where three of them belong to some particular Christoffel words appearing insome levels closer to the root of the Christoffel tree. The maximal value of this matrix is calledthe second order of balancedness for Christoffel words. From this matrix and this new orderof balancedness, we were able to show that the path followed by the fractions obtained fromthe ratio of the consecutive elements of Fibonacci sequence is a minimal path in the growth ofthis second order. In addition to that, these blocks are geometrically found on the Christoffelpath, by introducing a new factorization for the Christoffel words, called Symmetric standardfactorization. Similarly, we worked on finding a direct relation between the second order balancematrix U w and the initial Christoffel word without passing by the balance matrix B w but bystudying the set of factors of abelian vectors. All this work allow us to think about the initialtopic of research which is the synchronization of k balanced words. A complete study for the casek = 3 is given and we have discussed all the possible sub-cases for the synchronization by givingits seed, which is the starting column of the synchronized matrix. The second order balancematrix, with all its properties and decompositions form a good tool to study the synchronizationfor k generators that will be my future project of research. We have tried to use all the knowledgewe apply them on the reconstruction of digital convex polyominoes. Since the boundary wordof the digital convex polyominoe is made of Christoffel words with decreasing slopes. Hencewe introduce a split operator that respects the decreasing order of the slopes and therefore theconvexity is always conserved that is the first step toward the reconstruction.

Egyptian fractions are what we know as unit fractions that are of the form 1/n - with the exception, by the Egyptians, of 2/3. Egyptian fractions have actually played an important part in mathematics history with its primary roots in number theory. This paper will trace the history of Egyptian fractions by starting at the time of the Egyptians, working our way to Fibonacci, a geologist named Farey, continued fractions, Diophantine equations, and unsolved problems in number theory.

<p>The main focus of this dissertation is to find and explain the periodic points of certain algebraic functions that are related to some modular functions, which themselves can be represented by continued fractions. Some of these continued fractions are first explored by Srinivasa Ramanujan in early 20th century. Later on, much work has been done in terms of studying the continued fractions, and proving several relations, identities, and giving different representations for them.</p> <p><br></p> <p>The layout of this report is as follows. Chapter 1 has all the basic background knowledge and ingredients about algebraic number theory, class field theory, Ramanujan’s theta functions, etc. In Chapter 2, we look at the Ramanujan-Göllnitz-Gordon continued fraction that we call v(τ) and evaluate it at certain arguments in the field K = Q(√−d), with −d ≡ 1 (mod 8), in which the ideal (2) = ℘₂℘′₂  is a product of two prime ideals. We prove several identities related to itself and with other modular functions. Some of these are new, while some of them are known but with different proofs. These values of v(τ) are shown to generate the inertia field of ℘₂ or ℘′₂ in an extended ring class field over the field K. The conjugates over Q of these same values, together with 0, −1 ± √2, are shown to form the exact set of periodic points of a fixed algebraic function ˆF(x), independent of d. These are analogues of similar results for the Rogers-Ramanujan continued fraction. See [1] and [2]. This joint work with my advisor Dr. Morton, is submitted for publication to the New York Journal.</p> <p><br> In Chapters 3 and 4, we take a similar approach in studying two more continued fractions c(τ) and u(τ), the first of which is more commonly known as the Ramanujan’s cubic continued fraction. We show what fields a value of this continued fraction generates over Q, and we describe how the periodic points for described functions arise as values of these continued fractions. Then in the last chapter, we summarise all these results, give some possible directions for future research as well as mentioning some conjectures.</p>

Nós estudaremos o comportamento de difeomorfismos do círculo, tanto do ponto de vista combinatório quanto do ponto de vista topológico e da teoria da medida, seguindo os trabalhos de Michael Herman. A cada homeomorfismo do círculo podemos associar um número real positivo, denominado número de rotação. Mostraremos que existe um conjunto de números irracionais de medida de Lebesgue total na reta tal que, se f é um difeomorfismo do círculo de classe \'C POT. r \' que preserva a orientação, com r maior ou igual a 3 e com número de rotação nesse conjunto, então f é pelo menos \'C POT. r - 2\' -conjugada a uma translação irracional. Além disso, mostraremos que dado um caminho \'f IND. t\' de classe \'C POT. 1\' definido em um intervalo [a;b] no conjunto dos difeomorfismos do círculo de classe \'C POT. r\' que preservam a orientação, com r maior ou igual a 3, o conjunto dos parâmetros em que \'f IND. t\' é \'C POT. r - 2\' -conjugada a uma translação irracional tem medida de Lebesgue positiva, desde que os números de rotação em \'f IND. a\' e \'f IND. b\' sejam distintos / We will study the generic behavior of circle diffeomorphisms, in the combinatorial, topological and measure-theoretical sense, following the work of Michael Herman. To each order preserving homeomorphism of the circle we can associate a positive real number, called rotation number, which is invariant under conjugacy. We will show that there is a set of irrational numbers with full Lebesgue measure on R such that, if f is a circle diffeomorphism of class \'C POT. r\', with r greater or equal 3 and with rotation number in that set, then f is at least \'C POT. r - 2\' -conjugated to an irrational translation. Moreover, we will show that if ft is a \'C POT. 1\' -path defined on a interval [a;b] over the set of the circle diffeomorphisms orientation preserving, with r \'> or =\' 3, then the set of parameters where \'f IND. t\' is \'C POT. r - 2\' -conjugated to a irrational translation has positive Lebesgue measure, since the rotation numbers of \'f IND. a\' and \'f IND. b\' are distinct

Συνδέουμε τα Συνεχή Κλάσματα με τα Ορθογώνια Πολυώνυμα. Ξεκινώντας από τον Stieltjes και το ομώνυμο "Πρόβλημα Ροπών", φτάνουμε μέχρι τις μέρες μας μελετώντας αυτή τη σχέση με μεθόδους Συναρτησιακής Ανάλυσης. / We study the connection between Continued Fractions and Orthogonal Polynomials. We start from Stieltjes and his "Moment Problem". Then we present Chain sequences, methods of Functional Analysis and the Birth-Death processes.