A configuration space is a space whose points represent the possible states of a given physical system. As such they appear naturally both in theoretical physics and technical applications. For an example of the former, in analytical mechanics, the Lagrangian and Hamiltonian formulations of classical mechanics depend heavily on the use of a physical system’s configuration space for the description of its kinematical and dynamical behavior, and importantly, its evolution in time. As an example of a technical application, consider robotics, where the space of possible configurations of the mechanical linkages that make up a robot is an important tool in motion planning. In this case it is of particular interest to study the singularities of these mechanical linkages, to see if a given configuration is singular or not. This can be done with the help of configuration spaces and their topological properties. Arguably, the simplest configuration space possible arises when the system is just a collection of point-like particles in a plane. Despite its simplicity, the corresponding configuration space has substantial complexity and is of great interest in mathematics, physics and technology: For instance, it arises naturally in the mathematical modelling of robots performing tasks in a warehouse. In this thesis we go through the mathematics necessary to study the behaviour of paths in this space, which corresponds to motions of the particles. We use the theory of groups, algebraic topology, and manifolds to examine the properties of the configuration space of point-like particles in a plane. An important role in the discussion will be played by braids, which are certain collections of curves, interlaced in three-space. They are connected to many different topics in algebra, geometry, and mathematical physics, such as representation theory, the Yang-Baxter equation and knot theory. They are also important in their own right. Here we focus on their relation to configurations of points.

A graph configuration space is generated by the movement of a finite number of robots on a graph. These configuration spaces of points in a graph are topologically interesting objects. By using local, combinatorial properties, we define a new classification of graphs whose configuration spaces are pseudomanifolds with boundary. In algebraic topology, graph configuration spaces are closely related to classical braid groups, which can be described as fundamental groups of configuration spaces of points in the plane. We examine this relationship by finding a presentation for the fundamental group of one graph configuration space. / Master of Science

Submitted by Charles dos Anjos Moreira null (charles.anjos@hotmail.com) on 2017-11-30T00:05:25Z No. of bitstreams: 1 Versão Final - Charles dos Anjos Moreira.pdf: 1350502 bytes, checksum: bbaf5a250d792183c0b0e14bfc5f34dd (MD5) / Approved for entry into archive by Adriana Aparecida Puerta null (dripuerta@rc.unesp.br) on 2017-11-30T12:32:37Z (GMT) No. of bitstreams: 1 moreira_ca_me_rcla.pdf: 1350502 bytes, checksum: bbaf5a250d792183c0b0e14bfc5f34dd (MD5) / Made available in DSpace on 2017-11-30T12:32:37Z (GMT). No. of bitstreams: 1 moreira_ca_me_rcla.pdf: 1350502 bytes, checksum: bbaf5a250d792183c0b0e14bfc5f34dd (MD5) Previous issue date: 2017-11-01 / Esse trabalho trata de elementos da Topologia Algébrica, a qual tem como fundamental aplicação abordar questões acerca de Espaços Topológicos sob o ponto de vista algébrico. Uma das questões é tentar responder se dois espaços topológicos X e Y são homeomorfos. Neste sentido, o grupo fundamental é uma ferramenta algébrica útil por se tratar de um invariante topológico. Além disso, apresentamos o Teorema de van Kampen do ponto de vista da Linguagem de Categorias e Funtores. / This work treats of elements of the Algebraic Topology, which has as fundamental application to approach subjects concerning Topological Spaces under the algebraic point of view. One of the subjects is to try to answer if two topological spaces X and Y are homeomorphics. In this sense, the fundamental group is an useful algebraic tool for treating of an topological invariant. In addition, we presented the van Kampen's Theorem of the point of view of the language of Categories and Functors.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23686号 / 理博第4776号 / 新制||理||1684(附属図書館) / 京都大学大学院理学研究科数学・数理解析専攻 / (主査)教授 並河 良典, 教授 玉川 安騎男, 教授 望月 拓郎 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Regular Coverings - Structure and Complexity Michaela Seifrtová The thesis consists of two main parts, the first concentrated on the struc- ture of graph coverings, where different properties of regular graph coverings are presented, and the second dealing with computational complexity of the covering problem. Favorable results have been achieved in this area, proving the problem is solvable in polynomial time for all graphs whose order is a prime multiple of the order of the covered graph. 1

James W. Alexander, no artigo[1],mostra que se tivermos um mergulho PL f : \'S POT. 1\' × \'S POT. 1\' \'S POT. 3\', então o fecho de uma das componentes conexas de \'S POT. 3\' f(\'S POT. 1\' × \'S POT. 1\') é homeomorfo a um toro sólido, isto é, homeomorfo a \'S POT. 1\' × \'D POT. 2\'. Este teorema ficou conhecido por Teorema do toro de Alexander. Nesta dissertação, estamos detalhando a demonstração deste teorema feita em[25] que é diferente da demonstração apresentada em [1]. Mais geralmente, para um mergulho diferenciável f : \'S POT. p\' × \'S POT. q\' \'S POT. p + q+1\' , demonstra-se que o fecho de uma das componentes conexasde \'S POT. p +q + 1\' f(\'S POT. p\' × \'S POT. q\') é difeomorfo a \'S POT. p\' × \'D POT. q + 1\' se p q 1 e p + q \'DIFERENTE DE\' 3 ou se p = 2 e q = 1 um dos fechos será homeomorfo a \'S POT. 2\' × \'D POT. 2\' , nesta dissertação estaremos também detalhando estas demonstrações feita em [20] / James W. Alexander shows in[1] that the closure of one of the two connected components of \'S POT. 3\'f( \'S POT. 1 × \'S POT. 1\') is homeomorphic to a solid torus \'S POT. 1\' × \'D POT. 2\' , where f : \'S POT. 1\' ×\' SPOT. 1\' \'S POT. 3\' is a PL embedding. This result became known as Alexanders torus theorem. In this dissertation we are detailing the proof of this theorem made in[25] which is different from the demonstration presented in[1]. More generally, when considering a smooth embeding f : \'S POT. p\' × \'S POT. q\' \' SPOT. p+q+1\' , it is demonstrated that the closure of one of the two connected components \'S POT. p+q+1\' f (\'S POT. p\' × \'S POT. q\' ) is diffeomorphic to \'S POT. p\' × \'D POT. q+1\' if p q 1 and p+q \'DIFFERENT OF\' 3 or if p = 2 and q = 1 one of the closures will be homeomorphic to \'S POT. 2\' × \'D POT. 2\'. In this work we are also detailing the proves made in[20]

James W. Alexander, no artigo[1],mostra que se tivermos um mergulho PL f : \'S POT. 1\' × \'S POT. 1\' \'S POT. 3\', então o fecho de uma das componentes conexas de \'S POT. 3\' f(\'S POT. 1\' × \'S POT. 1\') é homeomorfo a um toro sólido, isto é, homeomorfo a \'S POT. 1\' × \'D POT. 2\'. Este teorema ficou conhecido por Teorema do toro de Alexander. Nesta dissertação, estamos detalhando a demonstração deste teorema feita em[25] que é diferente da demonstração apresentada em [1]. Mais geralmente, para um mergulho diferenciável f : \'S POT. p\' × \'S POT. q\' \'S POT. p + q+1\' , demonstra-se que o fecho de uma das componentes conexasde \'S POT. p +q + 1\' f(\'S POT. p\' × \'S POT. q\') é difeomorfo a \'S POT. p\' × \'D POT. q + 1\' se p q 1 e p + q \'DIFERENTE DE\' 3 ou se p = 2 e q = 1 um dos fechos será homeomorfo a \'S POT. 2\' × \'D POT. 2\' , nesta dissertação estaremos também detalhando estas demonstrações feita em [20] / James W. Alexander shows in[1] that the closure of one of the two connected components of \'S POT. 3\'f( \'S POT. 1 × \'S POT. 1\') is homeomorphic to a solid torus \'S POT. 1\' × \'D POT. 2\' , where f : \'S POT. 1\' ×\' SPOT. 1\' \'S POT. 3\' is a PL embedding. This result became known as Alexanders torus theorem. In this dissertation we are detailing the proof of this theorem made in[25] which is different from the demonstration presented in[1]. More generally, when considering a smooth embeding f : \'S POT. p\' × \'S POT. q\' \' SPOT. p+q+1\' , it is demonstrated that the closure of one of the two connected components \'S POT. p+q+1\' f (\'S POT. p\' × \'S POT. q\' ) is diffeomorphic to \'S POT. p\' × \'D POT. q+1\' if p q 1 and p+q \'DIFFERENT OF\' 3 or if p = 2 and q = 1 one of the closures will be homeomorphic to \'S POT. 2\' × \'D POT. 2\'. In this work we are also detailing the proves made in[20]

This thesis deals with toric ideals associated with finite simple graphs. In particular we establish some results pertaining to the nature of the generators and syzygies of toric ideals associated with finite simple graphs. The first result dealt with in this thesis expands upon work by Favacchio, Hofscheier, Keiper, and Van Tuyl which states that for G, a graph obtained by "gluing" a graph H1 to a graph H2 along an induced subgraph, we can obtain the toric ideal associated to G from the toric ideals associated to H1 and H2 by taking their sum as ideals in the larger ring and saturating by a particular monomial f. Our contribution is to sharpen the result and show that instead of a saturation by f, we need only examine the colon ideal with f^2. The second result treated by this thesis pertains to graded Betti numbers of toric ideals of complete bipartite graphs. We show that by counting specific subgraphs one can explicitly compute a minimal set of generators for the corresponding toric ideals as well as minimal generating sets for the first two syzygy modules. Additionally we provide formulas for some of the graded Betti numbers. The final topic treated pertains to a relationship between the fundamental group the finite simple graph G and the associated toric ideal to G. It was shown by Villareal as well as Hibi and Ohsugi that the generators of a toric ideal associated to a finite simple graph correspond to the closed even walks of the graph G, thus linking algebraic properties to combinatorial ones. Therefore it is a natural question whether there is a relationship between the toric ideal associated to the graph G and the fundamental group of the graph G. We show, under the assumption that G is a bipartite graph with some additional assumptions, one can conceive of the set of binomials in the toric ideal with coprime terms, B(IG), as a group with an appropriately chosen operation ⋆ and establish a group isomorphism (B(IG), ⋆) ∼= π1(G)/H where H is a normal subgroup. We exploit this relationship further to obtain information about the generators of IG as well as bounds on the Betti numbers. We are also able to characterise all regular sequences and hence compute the depth of the toric ideal of G. We also use the framework to prove that IG = (⟨G⟩ : (e1 · · · em)^∞) where G is a set of binomials which correspond to a generating set of π1(G). / Thesis / Doctor of Philosophy (PhD)

Le but de cette thèse est de considérer différentes questions sur les groupes projectifs et sur les arrangements de droites dans le plan projectif. Un groupe projectif est un groupe qui est isomorphe au groupe fondamental d'une variété projective lisse complexe. Pour étudier les groupes projectifs, des techniques sophistiquées de topologie algébrique et de géométrie algébrique ont été développées pendant les dernières décennies, par exemple la théorie des variétés caractéristiques combinée avec la théorie de Hodge s'est montrée être un outil puissant. Les arrangements de droites dans le plan projectif ont une place centrale dans l'étude des groupes projectifs. En effet, il y a beaucoup de questions ouvertes sur les groupes projectifs, et la théorie des arrangements d'hyperplans, en particulier celle des arrangements de droites, qui est un domaine très actif de recherche, peut suggérer des solutions à ces problèmes. En outre, les problèmes sur les groupes fondamentaux de complémentaires des arrangements d'hyperplans peuvent être réduits au cas des arrangements de droites, en utilisant le bien connu Théorème de Zariski du type de Lefschetz. Assez souvent, pour étudier les groupes projectifs ou quasi-projectifs, on considère d'abord les arrangements de droites pour obtenir des idées intuitives. Dans cette thèse nous obtenons aussi des résultats d'intérêts indépendants, par exemple sur les morphismes définis sur un produit d'espaces projectifs dans le Chapitre 4, sur la fibre générale de certains morphismes dans le Chapitre 5 et les critères sur les surfaces de type générales au Chapitre 7. / The objective of this thesis is to investigate various questions about projective groups and line arrangements in the projective plane. A projective group is a group which is isomorphic to the fundamental group of a smooth complex projective variety. To study projective groups, sophisticated techniques in algebraic topology and algebraic geometry have been developed in the passed decades, for instance, the theory of cohomology jump loci, together with Hodge theory, has been proven a powerful tool. Line arrangements in the projective plane are of special interest in the study of projective groups. Indeed, there are many open questions related to projective groups, and the theory of hyperplane arrangements, and in particular that of line arrangements, which is quite an active area of research, may provide insights for these problems. Furthermore, problems concerning the fundamental groups of the complements of hyperplane arrangements can be reduced to the case of line arrangements, due to the celebrated Zariski theorem of Lefschetz type. Very often, in the study of projective groups or quasi-projective groups, one usually considers line arrangements first to get some intuitive ideas. In this thesis, we also prove some theorems that are of independent interest and can be used elsewhere, for instance, we prove properties concerning morphisms from products of projective spaces in Chapter 4, we show that some morphisms have generic connected fibers in Chapter 5 and we give criteria for a projective surface to be of general type in Chapter 7.

Cette thèse est divisée en huit chapitres. D’abord, dans le Chapitre 1, on présente des résultats et des outils déjà connus qu’on utilisera dans la suite de la thèse. Le Chapitre 2 est consacré à résumer de maniére uniforme les nouveaux résultats présentés dans ce manuscrit.Les six chapitre restants sont originals. Dans les Chapitres 3 et 4 on démontre la chose suivante: soit $f:Yrightarrow X$ un morphisme lisse et prope sur une base $X$ lisse et géométriquament connexe sur un corps infini, finiment engendré et de caractéristique positive. Alors il y a beaucoup de points fermées $xin |X|$ tels que le rang du groupe de Néron-Severi de la fibre géometrique de $f$ en $x$ est le même du groupe de Néron-Severi de la fibre géométrique générique. On preuve ça de la façon suivante: on étudie la spécialisation du faisceau lisse $ell$-adique $R^2f_*Ql(1)$ ($ellneq p$); en suite, on le relit avec la spécialisation du F-isocristal $R^2f_{*,cris}mathcal O_{Y/K}(1)$ en passant par la catégorie des F-isocristaux surconvergents. Au final, la conjecture de Tate varationelle dans la cohomologie cristalline, nous permet de déduire le résultat sur les groupes de Néron-Severi depuis le résultat sur $R^2f_{*,cris}mathcal O_{Y/K}(1)$. Cela étend en caractéristique positive les résultats de Cadoret-Tamagawa et André en caractéristique zero.Les Chapitres 5 et 6 sont consacrés à l’étude des groupes de monodromie des F-isocristaux (sur)convergents. En particulier, les résultats dans le Chapitre 5 sont un travail en common avec Marco D'Addezio. On étude les tores maximaux des groupes de monodromie des F-isocristaux (sur)convergents et on utilise ça pour démontrer un cas particulier d’un conjecture de Kedlaya sur les homomorphismes de $F$-isocristeaux convergents. En utilisant ce cas particulier, on démontre que si $A$ est une variété abélienne sans facteurs d'isogonie isotrivial sur un corps de fonctions $F$ sur $overline{F}_p$, alors le groupe $A(F^{mathrm{perf}})_{tors}$ est fini. Cela peut être considéré comme une extension du théoreme de Lang—Néron et donne une réponse positive a une question d'Esnault. Dans le Chapitre 6, on défini une catégorie $overline Q_p$-linéaire des $F$-isocristeaux surconvergents et les groupes de monodromie de ces objets. En exploitant la théorie des compagnons pour les $F$-isocristeaux surconvergents et les faisceaux lisses, on étudie la théorie de spécialisation de ces groupes de monodromie en transférant les résultats du Chapitre 3 dans ce contexte.Les derniers deux chapitres complètent et affinent les résultats des chapitres précédents. Dans le Chapitre 7, on démontre que la conjecture de Tate pour les diviseurs sur les corps finiment engendrés et de caractéristique $p>0$ est une conséquence de la conjecture de Tate pour les diviseurs sur les corps finis de caractéristique $p>0$. Dans le Chapitre 8, on démontre des résultats de borne uniforme en caractéristique positive pour le groupes de Brauer des formes des variétés qui satisfasse la conjecture de Tate $ell$-adique pour les diviseurs. Cela étend en caractéristique positive un résultat de Orr-Skorobogatov en caractéristique zéro. / This thesis is divided in 8 chapters. Chapter ref{chapterpreliminaries} is of preliminary nature: we recall the tools that we will use in the rest of the thesis and some previously known results. Chapter ref{chapterpresentation} is devoted to summarize in a uniform way the new results obtained in this thesis.The other six chapters are original. In Chapters ref{chapterUOIp} and ref{chapterneron}, we prove the following: given a smooth proper morphism $f:Yrightarrow X$ over a smooth geometrically connected base $X$ over an infinite finitely generated field of positive characteristic, there are lots of closed points $xin |X|$ such that the rank of the N'eron-Severi group of the geometric fibre of $f$ at $x$ is the same of the rank of the N'eron-Severi group of the geometric generic fibre. To prove this, we first study the specialization of the $ell$-adic lisse sheaf $R^2f_*Ql(1)$ ($ellneq p$), then we relate it with the specialization of the F-isocrystal $R^2f_{*,crys}mathcal O_{Y/K}(1)$ passing trough the category of overconvergent F-isocrystals. Then, the variational Tate conjecture in crystalline cohomology, allows us to deduce the result on the N'eron-Severi groups from the results on $R^2f_{*,crys}mathcal O_{Y/K}(1)$. These extend to positive characteristic results of Cadoret-Tamagawa and Andr'e in characteristic zero.Chapters ref{chaptermarcuzzo} and ref{chapterpadic} are devoted to the study of the monodromy groups of (over)convergent F-isocrystals. Chapter ref{chaptermarcuzzo} is a joint work with Marco D'Addezio. We study the maximal tori in the monodromy groups of (over)convergent F-isocrystals and using them we prove a special case of a conjecture of Kedlaya on homomorphism of convergent $F$-isocrystals. Using this special case, we prove that if $A$ is an abelian variety without isotrivial geometric isogeny factors over a function field $F$ over $overline{F}_p$, then the group $A(F^{mathrm{perf}})_{tors}$ is finite. This may be regarded as an extension of the Lang--N'eron theorem and answer positively to a question of Esnault. In Chapter ref{chapterpadic}, we define $overline Q_p$-linear category of (over)convergent F-isocrystals and the monodromy groups of their objects. Using the theory of companion for overconvergent F-isocrystals and lisse sheaves, we study the specialization theory of these monodromy groups, transferring the result of Chapter ref{chapterUOIp} to this setting via the theory of companions.The last two chapters are devoted to complements and refinement of the results in the previous chapters. In Chapter ref{chaptertate}, we show that the Tate conjecture for divisors over finitely generated fields of characteristic $p>0$ follows from the Tate conjecture for divisors over finite fields of characteristic $p>0$. In Chapter ref{chapterbrauer}, we prove uniform boundedness results for the Brauer groups of forms of varieties in positive characteristic, satisfying the $ell$-adic Tate conjecture for divisors. This extends to positive characteristic a result of Orr-Skorobogatov in characteristic zero.