Centres and limit cycles for an extended Kukles system.
Closed orbits of fixed energy for a class of N-body problems
Codimension 4 singularities on reflectionally symmetryc planar vector fields.
The paper deals with the topological classification of singularities of vector fields on the plane which are invariant under reflection with respect to a line. As it has been proved in previous papers, such a classification is necessary to determine the different topological types of singularities of vector fiels on R3 whose linear part is invariant under rotations. To get the classification we use normal form theory and the the blowing-up method.
Coexisting cycles in a class of 3-D discrete maps
In this paper we consider the class of three-dimensional discrete maps M (x, y, z) = [φ(y), φ(z), φ(x)], where φ : ℝ → ℝ is an endomorphism. We show that all the cycles of the 3-D map M can be obtained by those of φ(x), as well as their local bifurcations. In particular we obtain that any local bifurcation is of co-dimension 3, that is three eigenvalues cross simultaneously the unit circle. As the map M exhibits coexistence...
Collision Orbits in the Anisotropic Kepler Problem.
Combining stability with symmetry properties in bifurcation problems
Conjugation to a shift and the splitting of invariant manifolds
We give sufficient conditions for a diffeomorphism in the plane to be analytically conjugate to a shift in a complex neighborhood of a segment of an invariant curve. For a family of functions close to the identity uniform estimates are established. As a consequence an exponential upper estimate for splitting of separatrices is established for diffeomorphisms of the plane close to the identity. The constant in the exponent is related to the width of the analyticity domain of the limit flow separatrix....
Construction of 0-1 matrices associated to period-doubling processes.
We elaborate a method allowing the determination of 0-1 matrices corresponding to dynamics of the interval having stable, 2k-periodic orbits, k belonging to N. By recurrence on the finite dimensional matrices, we establish the form of the infinite matrices (k --> ∞).
Contracting singular cycles
Contraintes génériques en géométrie de contact
Convergence results for periodic solutions of nonautonomous Hamiltonian systems
We prove some stability results for a certain class of periodic solutions of nonautonomous Hamiltonian systems in the case of Hamiltonian functions either with subquadratic growth or homogeneous with superquadratic growth. Thus we extend to the nonautonomous case some results recently established by the Authors for the autonomous case.
Création de points périodiques de tous types au voisinage des tores K.A.M.
Critical bifurcation surfaces of 3D discrete dynamics.
Critical point theory and nonlinear differential equations
Cycles and measure of bifurcation sets for two-dimensional diffeomorphisms.