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- On C1-robust transitivity of volume-preserving flowsPublication . Bessa, Mário; Rocha, JorgeWe prove that a divergence-free and C1-robustly transitive vector field has no singularities. Moreover, if the vector field is smooth enough then the linear Poincaré flow associated to it admits a dominated splitting over M.
- A dichotomy in area-preserving reversible mapsPublication . Bessa, Mário; Rodrigues, Alexandre A. P.In this paper we study R-reversible area-preserving maps f : M → M on a two-dimensional Riemannian closed manifold M, i.e. diffeomorphisms f such that R ◦ f = f−1 ◦ R where R: M → M is an isometric involution. We obtain a C1-residual subset where any map inside it is Anosov or else has a dense set of elliptic periodic orbits, thus establishing the stability conjecture in this setting. Along the paper we derive the C1-Closing Lemma for reversible maps and other perturbation toolboxes.
- Genericity of trivial Lyapunov spectrum for L-cocycles derived from second order linear homogeneous differential equationsPublication . Amaro, Dinis; Bessa, Mário; Vilarinho, HelderWe consider a probability space M on which an ergodic flow is defined. We study a family of continuous-time linear cocycles, referred to as kinetic, that are associated with solutions of the second-order linear homogeneous differential equation . Our main result states that for a generic subset of kinetic continuous-time linear cocycles, where generic means a Baire second category with respect to an -like topology on the infinitesimal generator, the Lyapunov spectrum is trivial.
- A remark on the topological stability of symplectomorphismsPublication . Bessa, Mário; Rocha, JorgeWe prove that the C^1 interior of the set of all topologically stable C1 symplectomorphisms is contained in the set of Anosov symplectomorphisms.
- Lyapunov exponents for linear homogeneous differential equationsPublication . Bessa, MárioWe consider linear continuous-time cocycles induced by second order linear homogeneous differential equations, where the coefficients evolve along the orbit of a flow defined on a closed manifold M. We are mainly interested in the Lyapunov exponents associated to most of the cocycles chosen when one allows variation of the parameters. The topology used to compare perturbations turn to be crucial to the conclusions.
- Global dynamics of generic 3-flowsPublication . Araújo, Vítor; Bessa, Mário; Pacífico, Maria JoséIn this chapter we present some results from the generic viewpoint, either for C 1 flows on 3-manifolds, or for C1 conservative flows on 3-manifolds. This means that we present some properties satisfied by a generic subset of all vector fields in compact 3-manifolds in the C1 topology.
- Homoclinic tangencies versus uniform hyperbolicity for conservative 3-flowsPublication . Bessa, Mário; Rocha, JorgeWe prove that a volume-preserving three-dimensional flow can be C 1 -approximated by a volume-preserving Anosov flow or else by another volume-preserving flow exhibiting a homoclinic tangency. This proves the conjecture of Palis for conservative 3-flows and with respect to the C1-topology.
- On the Lyapunov spectrum of relative transfer operatorsPublication . Bessa, Mário; Stadlbauer, ManuelWe analyze the Lyapunov spectrum of the relative Ruelle operator associated with a skew product whose base is an ergodic automorphism and whose fibers are full shifts. We prove that these operators can be approximated in the $C^0$-topology by positive matrices with an associated dominated splitting.
- On the area-preserving Domain-Straightening TheoremPublication . Bessa, Mário; Morais, PedroO clássico teorema da retificação do domínio no plano garante que, sob determinadas condições de não degeneracidade da derivada da função f : R^2 ---> R num ponto p existem abertos U e V de R2, p \in V e um difeomorfismo h: U ---> V tal que foh tem todas as suas curvas de nível em h−1(V ) contidas em retas. Provamos que tal deformação h pode ser feita preservando a área.
- On C1-generic chaotic systems in three-manifoldsPublication . Bessa, MárioLet M be a closed 3-dimensional Riemannian manifold. We exhibit a C1-residual subset of the set of volume-preserving 3-dimensional flows defined on very general manifolds M such that, any flow in this residual has zero metric entropy, has zero Lyapunov exponents and, nevertheless, is strongly chaotic in Devaney’s sense. Moreover, we also prove a corresponding version for the discrete-time case.