This thesis investigates the algebraic structure of certain quantum field theories in one space and one time dimension. These theories are integrable - essentially, highly constrained and therefore soluble. Thus, instead of having to use perturbative techniques, it is possible to conjecture their exact 5-matrices, which have the property that they are factorized into two-particle 5-matrices. In particular, there are two types of such theory: in one, scattering is purely elastic, whilst in the other, there is additional structure dictated by the Yang-Baxter equation. This thesis explores the algebraic structure of the latter and its links with the former. We begin, in chapter one, with an informal summary of the development of the subject, followed by a more mathematical exposition in chapter two. Chapter three constructs explicitly some exact factorized 5-matrices with Yang-Baxter structure, and comments on their features, both intrinsic and in relation to purely elastic 5-matrices. In particular, there is an unexplained close correspondence between the mass spectra and particle fusings in the two types of theory. The next three chapters attempt to shed some light on these features. Chapter four constructs similar 5-matrices, but based on quantum-deformed algebras rather than classical algebras. In chapter five we describe the structure of the 5-matrices when the particles they describe transform in irreducible representations of classical algebras. This leads us to consider the Yangian algebra, the representation theory of which underlies Yang-Baxter dependent 5-matrices, and which we therefore review briefly. We begin chapter six by reviewing the work which shows that the Yangian is also the charge algebra of the integrable quantum field theory, and subsequently show that the Yangian is also to a great extent present in the corresponding classical theory. We conclude with a brief seventh chapter describing the outlook for further research, followed by appendices containing respectively details of the Lagrangians of some integrable quantum field theories, a continuum formulation of the quantum inverse problem, explicit expressions for some of the R-matrices computed in the text, and a summary of known solutions of the Yang-Baxter equation.

Nesta dissertação abordamos o conjunto dos números complexos, apresentando sua forma algébrica e geométrica, demonstrando que se trata de um conjunto com estrutura algébrica de corpo. Apresentamos também as características de rotação e homotetia da operação de multiplicação, a contextualização histórica e finalizamos com uma proposta de abordagem para o ensino médio. Vemos também a impossibilidade de realizar rotação em três dimensões culminando com a criação dos quatérnios. / In this masters thesis we discuss the complex numbers set, showing its algebraic and geometric forms, demonstrating which it is a set with algebraic structure of field. We also presente the rotation characteristics and homothety of multiplication operation, the historical contextualization and we finalized with an approach proposal for the high school. We also see the impossibility of performing the rotation in three dimensions resulting the generation of quaternions.

La cryptologie est une des disciplines des mathématiques, elle est composée de deux sous-ensembles: la cryptographie et la cryptanalyse. Tandis que la cryptographie s'intéresse aux algorithmes permettant de modifier une information afin de la rendre inintelligible sans la connaissance d'un secret, la seconde s'intéresse aux méthodes mathématiques permettant de recouvrer l'information originale à partir de la seule connaissance de l'élément chiffré.La cryptographie se subdivise elle-même en deux sous-ensembles: la cryptographie symétrique et la cryptographie asymétrique. La première utilise une clef identique pour les opérations de chiffrement et de déchiffrement, tandis que la deuxième utilise une clef pour le chiffrement et une autre clef, différente de la précédente, pour le déchiffrement. Enfin, la cryptographie symétrique travaille soit sur des blocs d'information soit sur des flux continus d'information. Ce sont les algorithmes de chiffrement par blocs qui nous intéressent ici.L'objectif de la cryptanalyse est de retrouver l'information initiale sans connaissance de la clef de chiffrement et ceci dans un temps plus court que l'attaque par force brute. Il existe de nombreuses méthodes de cryptanalyse comme la cryptanalyse fréquentielle, la cryptanalyse différentielle, la cryptanalyse intégrale, la cryptanalyse linéaire...Beaucoup de ces méthodes sont maintenues en échec par les algorithmes de chiffrement modernes. En effet, dans un jeu de la lance et du bouclier, les cryptographes développent des algorithmes de chiffrement de plus en plus efficaces pour protéger l'information chiffrée d'une attaque par cryptanalyse. C'est le cas notamment de l'Advanced Encryption Standard (AES). Cet algorithme de chiffrement par blocs a été conçu par Joan Daemen et Vincent Rijmen et transformé en standard par le National Institute of Standards and Technology (NIST) en 2001. Afin de contrer les méthodes de cryptanalyse usuelles les concepteurs de l'AES lui ont donné une forte structure algébrique.Ce choix élimine brillamment toute possibilité d'attaque statistique, cependant, de récents travaux tendent à montrer, que ce qui est censé faire la robustesse de l'AES, pourrait se révéler être son point faible. En effet, selon ces études, cryptanalyser l'AES se ``résume'' à résoudre un système d'équations quadratiques symbolisant la structure du chiffrement de l'AES. Malheureusement, la taille du système d'équations obtenu et le manque d'algorithmes de résolution efficaces font qu'il est impossible, à l'heure actuelle, de résoudre de tels systèmes dans un temps raisonnable.L'enjeu de cette thèse est, à partir de la structure algébrique de l'AES, de décrire son algorithme de chiffrement et de déchiffrement sous la forme d'un nouveau système d'équations booléennes. Puis, en s'appuyant sur une représentation spécifique de ces équations, d'en réaliser une analyse combinatoire afin d'y détecter d'éventuels biais statistiques. / Cryptology is one of the mathematical fields, it is composed of two subsets: cryptography and cryptanalysis. While cryptography focuses on algorithms to modify an information by making it unintelligible without knowledge of a secret, the second focuses on mathematical methods to recover the original information from the only knowledge of the encrypted element.Cryptography itself is subdivided into two subsets: symmetric cryptography and asymmetric cryptography. The first uses the same key for encryption and decryption operations, while the second uses one key for encryption and another key, different from the previous one, for decryption. Finally, symmetric cryptography is working either on blocks of information either on continuous flow of information. These are algorithms block cipher that interests us here.The aim of cryptanalysis is to recover the original information without knowing the encryption key and this, into a shorter time than the brute-force attack. There are many methods of cryptanalysis as frequency cryptanalysis, differential cryptanalysis, integral cryptanalysis, linear cryptanalysis...Many of these methods are defeated by modern encryption algorithms. Indeed, in a game of spear and shield, cryptographers develop encryption algorithms more efficient to protect the encrypted information from an attack by cryptanalysis. This is the case of the Advanced Encryption Standard (AES). This block cipher algorithm was designed by Joan Daemen and Vincent Rijmen and transformed into standard by the National Institute of Standards and Technology (NIST) in 2001. To counter the usual methods of cryptanalysis of AES designers have given it a strong algebraic structure.This choice eliminates brilliantly any possibility of statistical attack, however, recent work suggests that what is supposed to be the strength of the AES, could prove to be his weak point. According to these studies, the AES cryptanalysis comes down to ``solve'' a quadratic equations symbolizing the structure of the AES encryption. Unfortunately, the size of the system of equations obtained and the lack of efficient resolution algorithms make it impossible, at this time, to solve such systems in a reasonable time.The challenge of this thesis is, from the algebraic structure of the AES, to describe its encryption and decryption processes in the form of a new Boolean equations system. Then, based on a specific representation of these equations, to achieve a combinatorial analysis to detect potential statistical biases.

Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2017-09-18T12:29:42Z No. of bitstreams: 1 Ana Paula Teles de Oliveira.pdf: 1429586 bytes, checksum: 83e9261fc458586c93c9fe22bebe556c (MD5) / Made available in DSpace on 2017-09-18T12:29:42Z (GMT). No. of bitstreams: 1 Ana Paula Teles de Oliveira.pdf: 1429586 bytes, checksum: 83e9261fc458586c93c9fe22bebe556c (MD5) Previous issue date: 2017-08-08 / In this research our aim is to investigate and evaluate a collection of data that will help understand the concept of the algebraic group, according to the question: What are the strength and limitations of a group of activities mentioned in examples and counterexamples in the algebraic structure group to generalize and formalize the context referred? It is possible to observe that this concept is organized through the following definitions: axiom and theories both containing examples and counterexamples. Our proposal consists on doing the opposite, meaning through examples and counterexamples it will be possible to study the concept involved. To start the research, we elaborated three activities, reorganized in four subgroups, which were elaborated in numeric and geometric exercises and fundamentals mentioned in Brousseau theories. We implemented the method of Design Experiments which helped us improve the activities, and thus evolve them with five individuals and subdivisions with two teams. This methodology has two perspectives: a prospective – that addresses a study of the activates proposed in the ways that will provide possible answers and further reflections - presenting an analysis of the answers and reflections obtained with the goal of meeting the proposed objective (the concepts of structure in the algebraic group). The people that took part in this research are students enrolled on the post-graduate of Mathematical Education. As a result, we point out as potentiality the movement between the phases of didactic situations in necessary concepts of the group algebraic structure identity element and associative property and also in relation to the worked examples as the reflection, composition of geometric transformations as an operation and when the same is closed in a given set and identity transformation as identity element in the set of geometric transformations. As limitations we observe that the phases of didactic situations did not occur in concepts such as binary and closed operation and the group algebraic structure. The activates done are not self-explanatory and thus needs to be clarified by individuals with the basic idea of element inverse, identity element, commutative and associative properties, composition of functions and symmetries in addition to the algebraic language / Nesta pesquisa nosso objetivo consiste em elaborar e analisar um conjunto de atividades para a constituição do conceito de estrutura algébrica grupo, direcionada pela questão: Quais são as potencialidades e limitações de um conjunto de atividades pautadas em exemplos e contraexemplos particulares de estrutura algébrica grupo para generalização e formalização do referido conceito? Observamos que esse conceito é organizado a partir de definições, axiomas, teorias, seguido de exemplos e contraexemplos. Nossa proposta consiste em fazermos uma inversão, ou seja, a partir de exemplos e contraexemplos estudarmos o conceito. Dessa forma, para iniciar os trabalhos de pesquisa, elaboramos três atividades, reorganizadas em quatro durante a pesquisa, que pautamos em exercícios numéricos e geométricos e fundamentamos teoricamente nas situações didáticas de Brousseau. Empregamos a metodologia Design Experiments, que nos permitiu aprimorar as atividades, e as desenvolvemos com cinco indivíduos, subdivididas em duas equipes. Essa metodologia envolve duas faces: uma prospectiva – que aborda um estudo das atividades propostas no sentido de fornecer possíveis respostas e resoluções, e outra reflexiva – que apresenta uma análise das respostas e resoluções obtidas com a finalidade de atingir o objetivo proposto (constituição do conceito de estrutura algébrica grupo). Os sujeitos de pesquisa, que compuseram as equipes, foram alunos matriculados no curso de pós-graduação em Educação Matemática. Como resultado, apontamos como potencialidade o movimento entre as fases das situações didáticas em conceitos necessários da estrutura algébrica grupo, elemento neutro e propriedade associativa e, ainda, exemplos trabalhados como reflexão, composição de transformações geométricas como uma operação, mesmo que seja fechada em um determinado conjunto, e transformação identidade como elemento neutro no conjunto das transformações geométricas. Em relação às limitações observamos que as fases das situações didáticas não ocorreram em conceitos como operação binária, fechada e a estrutura algébrica grupo. As atividades não são autoexplicativas e precisam ser desenvolvidas por indivíduos com ideias básicas de elemento inverso, elemento neutro, propriedades comutativa e associativa, composição de funções e simetrias, bem como a utilização de linguagem algébrica

Dependent type theories are a kind of mathematical foundations investigated both for the formalisation of mathematics and for reasoning about programs. They are implemented as the kernel of many proof assistants and programming languages with proofs (Coq, Agda, Idris, Dedukti, Matita, etc). Dependent types allow to encode elegantly and constructively the universal and existential quantifications of higher-order logics and are therefore adapted for writing logical propositions and proofs. However, their usage is not limited to the area of pure logic. Indeed, some recent work has shown that they can also be powerful for driving the construction of programs. Using more precise types not only helps to gain confidence about the program built, but it can also help its construction, giving rise to a new style of programming called Type-Driven Development. However, one difficulty with reasoning and programming with dependent types is that proof obligations arise naturally once programs become even moderately sized. For example, implementing an adder for binary numbers indexed over their natural number equivalents naturally leads to proof obligations for equalities of expressions over natural numbers. The need for these equality proofs comes, in intensional type theories (like CIC and ML) from the fact that in a non-empty context, the propositional equality allows us to prove as equal (with the induction principles) terms that are not judgementally equal, which implies that the typechecker can't always obtain equality proofs by reduction. As far as possible, we would like to solve such proof obligations automatically, and we absolutely need it if we want dependent types to be use more broadly, and perhaps one day to become the standard in functional programming. In this thesis, we show one way to automate these proofs by reflection in the dependently typed programming language Idris. However, the method that we follow is independent from the language being used, and this work could be reproduced in any dependently-typed language. We present an original type-safe reflection mechanism, where reflected terms are indexed by the original Idris expression that they represent, and show how it allows us to easily construct and manipulate proofs. We build a hierarchy of correct-by-construction tactics for proving equivalences in semi-groups, monoids, commutative monoids, groups, commutative groups, semi-rings and rings. We also show how each tactic reuses those from simpler structures, thus avoiding duplication of code and proofs. Finally, and as a conclusion, we discuss the trust we can have in such machine-checked proofs.