Nesta dissertação, definimos a geometria hiperbólica usando o disco de Poincaré (D2) e o semiplano superior (H2) com as respectivas propriedades. Além disso, apresentamos algumas funções e relações importantes da geometria hiperbólica; conceituamos as superfícies de Riemann, analisando suas propriedades e representações; estudamos o espaço de Teichmüller com a devida decomposição em calças. Esses temas são ferramentas necessárias para atingir o objetivo da dissertação: definir as coordenadas de Fenchel Nielsen como um sistema de coordenadas locais do espaço de Teichmüller Tg. / In this dissertation, we defined the hyperbolic geometry using the Poincares disk (D2) and upper half-plane (H2) with its properties. Besides, we presented some functions and important relations of the hyperbolic geometry; we conceptualize the Riemann surfaces, analyzing its properties and representations; we studied the Teichmüller Space with proper decomposition pants. These themes are essential tools to reach the goal of the work: The definition of the Fenchel Nielsen coordenates as local coordinate system of the Teichmüller space Tg.

We study relations between special elliptic isometries in the complex hyperbolic plane. A special elliptic isometry can be seen as a rotation around a fixed axis (a complex geodesic). Such an isometry is determined by specifying a nonisotropic point p (the polar point to the fixed axis) and a unitary complex number a, the angle of the isometry. Any relation between special elliptic isometries with rational angles gives rise to a representation H(k1;:::;kn) → PU(2;1), where H(k1;:::;kn) : = ⟨ r1; : : : ; rn ∣ rn : : : r1> = 1; rkii = 1 ⟩ and PU(2;1) stands for the group of orientation-preserving isometries of the complex hyperbolic plane. We denote by Rpα the special elliptic isometry determined by the nonisotropic point p and by the unitary complex number α. Relations of the form Rpnαn : : :Rp1α1 = 1 in PU(2;1), called special elliptic n-gons, can be modified by short relations known as bendings: given a product RqβRpα, there exists a one-parameter subgroup B : R → SU(2;1) such that B(s) is in the centralizer of Rqβ Rpα and RB(s)qβRB(s)pα = RqβRB(s)pα for every s ∈ R. Then, for each i = 1,...,n-1, we can change Rpi+1αi+1Rpiαi by RB(s)pi+1αi+1RB(s)piαi obtaining a new n-gon. We prove that the generic part of the space of pentagons with fixed angles and signs of points is connected by means of bendings. Furthermore, we describe certain length 4 relations, called f -bendings, and prove that the space of pentagons with fixed product of angles is connected by means of bendings and f -bendings. / Neste trabalho, estudamos relações entre isometrias elípticas especiais no plano hiperbólico complexo. Uma isometria elíptica especial pode ser vista como uma rotação em torno de um eixo fixo (uma geodésica complexa). Tal isometria é determinada especificando-se um ponto não-isotrópico p (o ponto polar do eixo fixo) bem como um número complexo unitário a (o ângulo da isometria). Qualquer relação entre isometrias elípticas especiais com ângulos racionais dá origem a uma representação H(k1;:::;kn) → PU(2;1), onde H(k1;:::;kn) : = ⟨ r1; : : : ; rn ∣ rn : : : r1 = 1; rkii = 1 ⟩ e PU(2;1) é o grupo de isometrias que preservam a orientação do plano hiperbólico complexo. Denotamos por Rpα a isometria elíptica especial determinada pelo ponto não-isotrópico p e pelo complexo unitário α. Relações da forma Rpnαn : : :Rp1α1 = 1 em PU(2;1), chamadas n-ágonos elípticos especiais, podem ser modificadas a partir de relações curtas conhecidas como bendings: dado um produto RqβRpα, existe um subgrupo uniparamétrico B : R → SU(2;1) tal que B(s) está no centralizador de RqβRpα e RB(s)qβRB(s)pα = RqβRpα para todo s ∈ R. Assim, para cada i = 1; : : : ;n-1, podemos mudar Rpi+1α+1Rpiαi por RB(s)pi+1α+1RB(s)piα+1RB(s)piαi obtendo um novo n-ágono. Provamos que a parte genérica do espaço de pentágonos com ângulos e sinais de pontos fixados é conexa por meio de bendings. Além disso, descrevemos certas relações de comprimento 4, os f -bendings, e provamos que o espaço de pentágonos com produto de ângulos fixado é conexo por meio de bendings e f -bendings.

We study relations between special elliptic isometries in the complex hyperbolic plane. A special elliptic isometry can be seen as a rotation around a fixed axis (a complex geodesic). Such an isometry is determined by specifying a nonisotropic point p (the polar point to the fixed axis) and a unitary complex number a, the angle of the isometry. Any relation between special elliptic isometries with rational angles gives rise to a representation H(k1;:::;kn) → PU(2;1), where H(k1;:::;kn) : = ⟨ r1; : : : ; rn ∣ rn : : : r1> = 1; rkii = 1 ⟩ and PU(2;1) stands for the group of orientation-preserving isometries of the complex hyperbolic plane. We denote by Rpα the special elliptic isometry determined by the nonisotropic point p and by the unitary complex number α. Relations of the form Rpnαn : : :Rp1α1 = 1 in PU(2;1), called special elliptic n-gons, can be modified by short relations known as bendings: given a product RqβRpα, there exists a one-parameter subgroup B : R → SU(2;1) such that B(s) is in the centralizer of Rqβ Rpα and RB(s)qβRB(s)pα = RqβRB(s)pα for every s ∈ R. Then, for each i = 1,...,n-1, we can change Rpi+1αi+1Rpiαi by RB(s)pi+1αi+1RB(s)piαi obtaining a new n-gon. We prove that the generic part of the space of pentagons with fixed angles and signs of points is connected by means of bendings. Furthermore, we describe certain length 4 relations, called f -bendings, and prove that the space of pentagons with fixed product of angles is connected by means of bendings and f -bendings. / Neste trabalho, estudamos relações entre isometrias elípticas especiais no plano hiperbólico complexo. Uma isometria elíptica especial pode ser vista como uma rotação em torno de um eixo fixo (uma geodésica complexa). Tal isometria é determinada especificando-se um ponto não-isotrópico p (o ponto polar do eixo fixo) bem como um número complexo unitário a (o ângulo da isometria). Qualquer relação entre isometrias elípticas especiais com ângulos racionais dá origem a uma representação H(k1;:::;kn) → PU(2;1), onde H(k1;:::;kn) : = ⟨ r1; : : : ; rn ∣ rn : : : r1 = 1; rkii = 1 ⟩ e PU(2;1) é o grupo de isometrias que preservam a orientação do plano hiperbólico complexo. Denotamos por Rpα a isometria elíptica especial determinada pelo ponto não-isotrópico p e pelo complexo unitário α. Relações da forma Rpnαn : : :Rp1α1 = 1 em PU(2;1), chamadas n-ágonos elípticos especiais, podem ser modificadas a partir de relações curtas conhecidas como bendings: dado um produto RqβRpα, existe um subgrupo uniparamétrico B : R → SU(2;1) tal que B(s) está no centralizador de RqβRpα e RB(s)qβRB(s)pα = RqβRpα para todo s ∈ R. Assim, para cada i = 1; : : : ;n-1, podemos mudar Rpi+1α+1Rpiαi por RB(s)pi+1α+1RB(s)piα+1RB(s)piαi obtendo um novo n-ágono. Provamos que a parte genérica do espaço de pentágonos com ângulos e sinais de pontos fixados é conexa por meio de bendings. Além disso, descrevemos certas relações de comprimento 4, os f -bendings, e provamos que o espaço de pentágonos com produto de ângulos fixado é conexo por meio de bendings e f -bendings.

Dans cette thèse nous étudions un super-analogue de l'espace de Teichmüller des surfaces à trous. Le but de notre étude est la construction sur cet espace de coordonnées analogues aux coordonnées de décalage de Thurston-Bonahon-Fock-Penner. Ces coordonnées dépendent du choix d'une triangulation idéale de la surface de départ. Nous étudions les changements de coordonnées lorsque l'on change cette triangulation de la surface. Nous démontrons également que cet espace possède une structure de Poisson canonique et que cette structure est indépendante du choix de la triangulation. / In this thesis we study a superanalogue of the Teichmüller space of surfaces with holes.The aim of our study is the construction of coordinates on this space which are analogousto the Thurston-Bonahon-Fock-Penner shear coordinates. These coordinates depend on a choice of an ideal triangulation of the given surface. We study the changes of coordinates when we modify the triangulation by elementary moves. We also show that this spaceadmits a canonical Poisson structure which is independent of the choice of a triangulation.

Nesta dissertação, definimos a geometria hiperbólica usando o disco de Poincaré (D2) e o semiplano superior (H2) com as respectivas propriedades. Além disso, apresentamos algumas funções e relações importantes da geometria hiperbólica; conceituamos as superfícies de Riemann, analisando suas propriedades e representações; estudamos o espaço de Teichmüller com a devida decomposição em calças. Esses temas são ferramentas necessárias para atingir o objetivo da dissertação: definir as coordenadas de Fenchel Nielsen como um sistema de coordenadas locais do espaço de Teichmüller Tg. / In this dissertation, we defined the hyperbolic geometry using the Poincares disk (D2) and upper half-plane (H2) with its properties. Besides, we presented some functions and important relations of the hyperbolic geometry; we conceptualize the Riemann surfaces, analyzing its properties and representations; we studied the Teichmüller Space with proper decomposition pants. These themes are essential tools to reach the goal of the work: The definition of the Fenchel Nielsen coordenates as local coordinate system of the Teichmüller space Tg.

L'objectif de la thèse est de construire une compactification géométrique de l'espace des structures de demi-translation sur une surface S compacte, connexe, orientable, de genre au moins égal à 2. Il s’inscrit dans le très large thème d’étude des déformations de structures géométriques sur les surfaces. Une structure de demi-translation sur S est une métrique localement euclidienne (de courbure constante nulle) sur S, avec des singularités coniques d'angles k pi, avec k un entier et k>2, telle que l'holonomie de tout lacet lisse de S, disjoint des singularités, est Id ou -Id.Je définis l'ensemble des structures mixtes sur S, qui sont des structures arborescentes (au sens de Drutu-Sapir), équivariantes par le groupe fondamentalde S et CAT(0), obtenues par recollement de pièces par des arêtes, éventuellement réduites à des points, telles que l'espace obtenu par écrasement des pièces est un arbre réel simplicial (la plupart des arêtes ont une longueur non nulle), et les pièces sont ou bien des arbres réels, ou bien des revêtements universels de sous-surfaces (ouvertes) de S, munies de structures de demi-translation. Je munis l'espace Mix(Sigma) des (classes d'isométries équivariantes par le groupe fondamental de S) de structures mixtes sur S d'une topologie géométrique naturelle, appelée topologie de Gromov équivariante. Je montre alors, par des techniques d'ultralimites à la Gromov, que l'espace Flat(S) des (classes d'isotopie de) structures de demi-translation sur S, identifié à l’ensemble des structures de demi-translation équivariantes par le groupe fondamental de S sur le revêtement universel de S, est un ouvert dense de Mix(S), et que le projectifié PMix(S), muni de la topologie quotient, est compact. Le projectifié PMix(S) est donc une compactification du projectifié PFlat(S) de l'espace Flat(S) (qui s'identifie à l'espace des structure de demi-translation d'aire 1 sur S). / The goal of this thesis is to build a geometric compactification of the space of half-translation structures on a connected, compact surface S, with genus at least 2. It is a part of the wide thema of study of the deformations of metric structures on surfaces.A half-translation structure on S is a locally euclidean metric (with null constant curvature) on S, with conical singularities of angles k pi, with k an integer and k>2, such that the holonomy of every smooth curve of S, disjoint from the singularities, is contained in Id or -Id.I define the set of mixed structures on S, which are tree-graded spaces (in the sense of Drutu-Sapir), equivariant by the fundamental group of S and CAT(0), obtained by gluing some pieces by some edges, possibly reduced to a point, such that the space obtained by replacing the pieces by some points is a simplicialtree (most edges have a positive length), and the pieces are either some trees or some universal covers of (open) subsurfaces of S endowed with a half-translation structures. I endow the space Mix(S) of (classes of isometry equivariant by the fundamental group of S of) mixed structures on S with a natural geometric topology, called the Gromov equivariant topology. I show, by techniques using ultralimits "à la Gromov", that the space Flat(S) of (isotopy classes of) half-translation structures on S, identified with the set of half-translation structures on the universal cover of S which are equivariant for the fundamental group of S, is a dense and open subset of Mix(S), and the projectified space PMix(S) is compact. The projectified space PMix(S) is then a compactification of the projectified space PFlat(S) (which identifies with the space of half-translations structures of area 1 on S.

Nesta disertação estudamos algumas ferramentas básicas relacionadas aos espaços de Teichmüller. Introduzimos o espaço de Teichmüller de gênero g ≥ 1, denotado por Tg. O objetivo principal é construir as coordenadas de Fenchel-Nielsen ωG : Tg → R3g-3+ × R3g-3 para cada grafo trivalente marcado G. / In this dissertation we study some basic tools related to Teichmüller space. We introduce the Teichmüller space of genus g ≥ 1, denoted by Tg. The main goal is to construct the Fenchel-Nielsen coordinates ωG : Tg → R3g-3+ × R3g-3 to each marked cubic graph G.

Dans ce travail nous nous intéressons à la géométrie de l’espace de Teichmüller via la longueur extrémale et à sa relation avec d’autres géométries. En effet, via le théorème d’uniformisation de Poincaré, l’espace de Teichmüller d’une surface orientable de type finie est un espace qui “classifie” aussi bien les structures hyperboliques de cette surface que les structures conformes. Suivant la classification utilisée, on obtient deux compactifications différentes de cet espace, qui sont respectivement la compactification de Thurston et la compactification de Gardiner-Masur. La première étant induite par la longueur hyperbolique et la deuxième par la longueur extrémale. Dans une première partie, on considère les compactifications dites “réduites” de Thurston et Gardiner-Masur. On montre qu’il existe une bijection naturelle entre les deux et que le groupe des auto-homéomorphismes du bord réduit de Thurston est canoniquement isomorphe au groupe modulaire étendu de la surface sous-jacente. Dans une deuxième partie, on étudie la convergence de certaines déformations de structures conformes aussi bien sur le bord de Thurston que sur celui de Gardiner-Masur. Ces déformations, appelées déformations horocycliques, sont un analogue des tremblements de terre de structures hyperboliques. Enfin, dans une troisième et dernière partie, on introduit une compactification à la Gardiner-Masur de l’espace de Teichmüller d’une surface à bord. On généralise des résultats obtenus dans le cas sans bord, et on établit quelques différences. / In this thesis we are interested in the extremal length geometry of Teichmüller space and the links with other geometries. In particular, we work on two different compactifications of Teichmüller space, namely, the Thurston compactification and the Gardiner-Masur compactification. In the first part, we consider the so-called reduced compactifications of Thurston and Gardiner-Masur. We show that there exists a canonical bijection between them and that the group of self-homeomorphisms of the reduced Thurston boundary is canonicaly isomorphic (except for a few cases) to the extended mapping class group of the corresponding surface. In the second part, we study the asymptotic behaviour of some conformal structure deformations to the Thuston boundary and to the Gardiner-Masur boundary. These deformations are called horocyclic deformations and they are analogous to earthquakes of hyperbolic structures. Finally, in the last part, using extremal length we extend the notion of Gardiner-Masur compactification to surfaces with non-empty boundary, and we investigate differences with the case without boundary.

Nesta disertação estudamos algumas ferramentas básicas relacionadas aos espaços de Teichmüller. Introduzimos o espaço de Teichmüller de gênero g ≥ 1, denotado por Tg. O objetivo principal é construir as coordenadas de Fenchel-Nielsen ωG : Tg → R3g-3+ × R3g-3 para cada grafo trivalente marcado G. / In this dissertation we study some basic tools related to Teichmüller space. We introduce the Teichmüller space of genus g ≥ 1, denoted by Tg. The main goal is to construct the Fenchel-Nielsen coordinates ωG : Tg → R3g-3+ × R3g-3 to each marked cubic graph G.

Cette thèse porte sur certaines familles à un paramètre de surfaces de Riemann compactes de genre 2 définies par des surfaces de translation. Les familles que nous considérons constituent des géodésiques de Teichmüller dans l'espace des modules. Nous nous attachons en particulier à décrire ces surfaces par leurs matrices des périodes et par les équations des courbes algébriques associées. Nous étudions notamment les automorphismes admissibles par les surfaces qui sont des courbes réelles à trois composantes réelles dans ces familles. Le principal résultat consiste en une caractérisation explicite des matrices des périodes des courbes réelles à trois composantes réelles appartenant à la famille obtenue par projection dans l'espace des modules de la SL(2,R)-orbite de la surface de translation en "L" pavée par trois carreaux. Nous montrons enfin, grâce à une interprétation en termes de transformations de Schwarz-Christoffel, comment calculer numériquement une équation de la courbe algébrique définie par une surface de translation en "L".