Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Matemática, 2015. / Submitted by Andrielle Gomes (andriellemacedo@bce.unb.br) on 2015-07-02T15:45:10Z No. of bitstreams: 1 2015_ElaineCristinedeSouzaSilva.pdf: 1344979 bytes, checksum: 58caef736144b453933f8e75cb04a646 (MD5) / Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2015-07-29T15:13:33Z (GMT) No. of bitstreams: 1 2015_ElaineCristinedeSouzaSilva.pdf: 1344979 bytes, checksum: 58caef736144b453933f8e75cb04a646 (MD5) / Made available in DSpace on 2015-07-29T15:13:33Z (GMT). No. of bitstreams: 1 2015_ElaineCristinedeSouzaSilva.pdf: 1344979 bytes, checksum: 58caef736144b453933f8e75cb04a646 (MD5) / Esta dissertação trata dos números de Liouville. O estudo foi baseado nos trabalhos de Burger, Caveny, Kumar, Thangadurai e Waldschmidt. Dentre os principais resultados deste trabalho, destacam-se: a generalização de um resultado de Erdos, ao provar que alguns números reais podem ser escritos como F(σ;Ƭ), onde σ e Ƭ são números de Liouville, para uma classe muito grande de funções F(x; y); a determinação de condições suficientes para que a potenciação de números transcendentes seja um número transcendente; e a apresentação de resultados recentes sobre independência algébrica relacionados com os números de Liouville e a Conjectura de Schanuel. / This work is about Liouville numbers. The study was based on works due to Burger, Caveny, Kumar, Thangadurai and Waldschmidt. Among the main results, we highlight: a generalization of an Erd os result, proving that some real numbers can be written as F(σ, Ƭ ), where σ and Ƭ are Liouville numbers, for a very large class of functions F(x; y); some sufficient conditions for which the power of two transcendental numbers is still transcendental; and some recent results about algebraic independence related to Liouville numbers and Schanuel's conjecture.

The objective of this thesis is to provide a detailed analysis of a new invariant for Grothendieck topoi in the special case of the topos of continuous G-sets and continuous G-equivariant maps. We use a well-known site to present the isotropy group in elementary terms, as systems of right cosets of open subgroups of G. We establish properties of the the isotropy group for an arbitrary topological group and use the developed theory to compute the isotropy group for the Schanuel topos.

In this thesis we study Ax-Schanuel type inequalities for abstract differential equations. A motivating example is the exponential differential equation. The Ax-Schanuel theorem states positivity of a predimension defined on its solutions. The notion of a predimension was introduced by Hrushovski in his work from the 1990s where he uses an amalgamation-with-predimension technique to refute Zilber's Trichotomy Conjecture. In the differential setting one can carry out a similar construction with the predimension given by Ax-Schanuel. In this way one constructs a limit structure whose theory turns out to be precisely the first-order theory of the exponential differential equation (this analysis is due to Kirby (for semiabelian varieties) and Crampin, and it is based on Zilber's work on pseudo-exponentiation). One says in this case that the inequality is adequate. Thus, by an Ax-Schanuel type inequality we mean a predimension inequality for a differential equation. Our main question is to understand for which differential equations one can find an adequate predimension inequality. We show that this can be done for linear differential equations with constant coefficients by generalising the Ax-Schanuel theorem. Further, the question turns out to be closely related to the problem of recovering the differential structure in reducts of differentially closed fields where we keep the field structure (which is quite an interesting problem in its own right). So we explore that question and establish some criteria for recovering the derivation of the field. We also show (under some assumptions) that when the derivation is definable in a reduct then the latter cannot satisfy a non-trivial adequate predimension inequality. Another example of a predimension inequality is the analogue of Ax-Schanuel for the differential equation of the modular j-function due to Pila and Tsimerman. We carry out a Hrushovski construction with that predimension and give an axiomatisation of the first-order theory of the strong Fraïssé limit. It will be the theory of the differential equation of j under the assumption of adequacy of the predimension. We also show that if a similar predimension inequality (not necessarily adequate) is known for a differential equation then the fibres of the latter have interesting model theoretic properties such as strong minimality and geometric triviality. This, in particular, gives a new proof for a theorem of Freitag and Scanlon stating that the differential equation of j defines a trivial strongly minimal set.

Nous traitons ici de questions d’effectivité dans les problèmes de Mordell-Lang et de Schanuel où la notion de hauteur algébrique joue un rôle central.Dans un premier temps nous revisitions la méthode de Vojta-Faltings dans un cadre général, en y incluant notamment un procédé de descente uniforme qui permet d’optimiser le nombre de recours au pesant mécanisme d’approximation diophantienne. Nous proposons ensuite une application de ce résultat au problème de Mordell-Lang plus Bogomolov dans le tore, qui consiste à décrire un sousensemble algébrique X comme réunion de translatés de sous-tores inclus dans X moyennant de se restreindre à un sous-groupe de rang fini épaissi. Nous nous appuyons en particulier sur un énoncé d’Amoroso et Viada concernant le problème de Bogomolov dans ce contexte et améliorons les bornes antérieures obtenues par Rémond.Dans un second temps, nous établissons une version du théorème de Schanuel dans le cadre d’un espace adélique hermitien sur un corps de nombres. Nous donnons une estimation asymptotique du nombre de points projectifs de hauteur bornée pour une hauteur définie par une famille de normes sur les complétés en chaque place, vérifiant certaines conditions mais sans hypothèse de pureté dans le cas ultramétrique. Le terme reste obtenu est totalement explicite et linéaire en le régulateur du corps de nombres grâce au recours à une méthode introduite par Schmidt. Nous traitons également plusieurs applications de ce résultat, notamment aux problèmes de Dedekind-Weber et de Loher-Masser. / We are dealing here with effectiveness matters about the Mordell-Lang and Schanuel problems where algebraic heights play a central role.At the first time, we modify the Vojta-Faltings method in a general context by including some uniform descending process which has the advantage to optimize the number of iterations of the heavy Diophantine approximation mechanism. We then propose an application to the toric Mordell-Lang plus Bogomolov problem whose aim is to describe an algebraic subset X as the union of translates of closed, irreducible subgroups included in X when restricted to some enlarged, finite rank subgroup. In particular we use a theorem of Amoroso and Viada about the Bogomolov problem in this context and we improve the previous bound given by Rémond.At the second time, we prove a version of the theorem of Schanuel in the setting of a Hermitian adelic vector bundle over a number field. We give an asymptotic estimate for the number of projective points of bounded height for heights given by a family of norms over the completions at each place, satisfying several conditions but no purity hypothesis in the ultrametric case. The error term is totally explicit and linear with respect to the regulator of the number field through the use of Schmidt’s method. We finally give some applications of our result in particular to the Dedekind-Weber and Loher-Masser problems.