0000000000208025
AUTHOR
Jean-marie Lion
Inégalité de Lojasiewicz en géométrie pfaffienne
We give a Lojasiewicz inequality for the $o$-minimal structure generate by Rolle leaves over the globally subanalytic sets. We obtain uniform estimates in the iterated exponentials scale.
Nature log-analytique du volume des sous-analytiques
Using a preparation theorem for subanalytic functions and Lipschitz stratification for compact subanalytic sets we prove that volumes of slices of globally subanalytic sets and density have a log-analytic nature. We also prove that the set of parameters for which the volume of fiber is finite is globally subanalytic.
Differential equations over polynomially bounded o-minimal structures
We investigate the asymptotic behavior at +∞ of non-oscillatory solutions to differential equations y' = G(t, y), t > a, where G: R 1+l → R l is definable in a polynomially bounded o-minimal structure. In particular, we show that the Pfaffian closure of a polynomially bounded o-minimal structure on the real field is levelled.
Champs de vecteurs analytiques et champs de gradients
A theorem of Łojasiewicz asserts that any relatively compact solution of a real analytic gradient vector field has finite length. We show here a generalization of this result for relatively compact solutions of an analytic vector field X with a smooth invariant hypersurface, transversally hyperbolic for X, where the restriction of the field is a gradient. This solves some instances of R. Thom's Gradient Conjecture. Furthermore, if the dimension of the ambient space is three, these solutions do not oscillate (in the sense that they cut an analytic set only finitely many times); this can also be applied to some gradient vector fields.
Théorème de Gabrielov et fonctions log-exp-algébriques
Resume Nous obtenons le theoreme de Wilkie sur les fonctions log-exp-algebriques du theoreme du complementaire ≪ explicite ≫ de Gabrielov, et de notre presentation geometrique du theoreme de van den Dries, Macintyre et Marker sur les fonctions log-exp-analytiques.
Volumes transverses aux feuilletages d'efinissables dans des structures o-minimales
Let Fλ be a family of codimension p foliations defined on a family Mλ of manifolds and let Xλ be a family of compact subsets of Mλ. Suppose that Fλ, Mλ and Xλ are definable in an o-minimal structure and that all leaves of Fλ are closed. Given a definable family Ωλ of differential p-forms satisfaying iZ Ωλ = 0 forany vector field Z tangent to Fλ, we prove that there exists a constant A > 0 such that the integral of on any transversal of Fλ intersecting each leaf in at most one point is bounded by A. We apply this result to prove that p-volumes of transverse sections of Fλ are uniformly bounded.
Une propriété des solutions non spiralantes d’équations différentielles analytiques du plan
Resume On montre que le contact entre deux courbes integrales singulieres et non spiralantes des deux equations de Pfaff analytiques du plan est au plus exponentiellement petit.