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Relations de Fuchs pour les systèmes différentiels réguliers

Eduardo Corel (2001)

Bulletin de la Société Mathématique de France

Dans cet article, nous montrons que la notion analytique d’exposants développée par Levelt pour les systèmes différentiels linéaires en une singularité régulière s’interprète algébriquement en termes d’invariants de réseaux, relatifs à un réseau stable maximal que nous appelons « réseau de Levelt ». Nous obtenons en particulier un encadrement pour la somme des exposants des systèmes n’ayant que des singularités régulières sur 1 ( ).

Relative Bogomolov extensions

Robert Grizzard (2015)

Acta Arithmetica

A subfield K ⊆ ℚ̅ has the Bogomolov property if there exists a positive ε such that no non-torsion point of K × has absolute logarithmic height below ε. We define a relative extension L/K to be Bogomolov if this holds for points of L × K × . We construct various examples of extensions which are and are not Bogomolov. We prove a ramification criterion for this property, and use it to show that such extensions can always be constructed if some rational prime has bounded ramification index in K.

Relatively complete ordered fields without integer parts

Mojtaba Moniri, Jafar S. Eivazloo (2003)

Fundamenta Mathematicae

We prove a convenient equivalent criterion for monotone completeness of ordered fields of generalized power series [ [ F G ] ] with exponents in a totally ordered Abelian group G and coefficients in an ordered field F. This enables us to provide examples of such fields (monotone complete or otherwise) with or without integer parts, i.e. discrete subrings approximating each element within 1. We include a new and more straightforward proof that [ [ F G ] ] is always Scott complete. In contrast, the Puiseux series field...

Remarks on the intrinsic inverse problem

Daniel Bertrand (2002)

Banach Center Publications

The intrinsic differential Galois group is a twisted form of the standard differential Galois group, defined over the base differential field. We exhibit several constraints for the inverse problem of differential Galois theory to have a solution in this intrinsic setting, and show by explicit computations that they are sufficient in a (very) special situation.

Currently displaying 1401 – 1420 of 2019