Lagrangian singularities of invariant tori of hamiltonian systems with two degrees of freedom.
Law of the Iterated Logarithm for Tranisitive C... Anosov Flows and Semiflows over Maps of the Interval.
Le «closing lemma» en topologie
Linearisierung formal-biholomorpher Abbildungen und Interationsprobleme.
Linearization of Normally Hyperbolic Diffeomorphisms and Flows
Local Groups of Differentiable Transformations.
Matsuki correspondence for sheaves.
Meromorphic extensions of generalised zeta functions.
Minimal and distal functions on semidirect products of groups
Mise en position optimale de tores par rapport à un flot d'Anosov.
Modular dynamical systems on networks
We propose a new framework for the study of continuous time dynamical systems on networks. We view such dynamical systems as collections of interacting control systems. We show that a class of maps between graphs called graph fibrations give rise to maps between dynamical systems on networks. This allows us to produce conjugacy between dynamical systems out of combinatorial data. In particular we show that surjective graph fibrations lead to synchrony subspaces in networks. The injective graph fibrations,...
Modulus of analytic classification for the generic unfolding of a codimension 1 resonant diffeomorphism or resonant saddle
We consider germs of one-parameter generic families of resonant analytic diffeomorphims and we give a complete modulus of analytic classification by means of the unfolding of the Écalle modulus. We describe the parametric resurgence phenomenon. We apply this to give a complete modulus of orbital analytic classification for the unfolding of a generic resonant saddle of a 2-dimensional vector field by means of the unfolding of its holonomy map. Here again the modulus is an unfolding of the Martinet-Ramis...
Morales-Ramis Theorems via Malgrange pseudogroup
In this article we give an obstruction to integrability by quadratures of an ordinary differential equation on the differential Galois group of variational equations of any order along a particular solution. In Hamiltonian situation the condition on the Galois group gives Morales-Ramis-Simó theorem. The main tools used are Malgrange pseudogroup of a vector field and Artin approximation theorem.
Nilpotent and recursive flows.
Nonlinear connections and semisprays on tangent manifolds.
Nonseparated manifolds and completely unstable flows.
Normal forms for singularities of one dimensional holomorphic vector fields.
Normal forms with exponentially small remainder and Gevrey normalization for vector fields with a nilpotent linear part
We explore the convergence/divergence of the normal form for a singularity of a vector field on with nilpotent linear part. We show that a Gevrey- vector field with a nilpotent linear part can be reduced to a normal form of Gevrey- type with the use of a Gevrey- transformation. We also give a proof of the existence of an optimal order to stop the normal form procedure. If one stops the normal form procedure at this order, the remainder becomes exponentially small.
Normalization of Poincaré singularities via variation of constants.
We present a geometric proof of the Poincaré-Dulac Normalization Theorem for analytic vector fields with singularities of Poincaré type. Our approach allows us to relate the size of the convergence domain of the linearizing transformation to the geometry of the complex foliation associated to the vector field.
Note à propos d'un résultat de Kowada sur les flots analytiques