Preprint D13/2005
On the volume of singular-hyperbolic sets
Vilton Pinheiro | Alves, Jose | Araujo, Vitor | Pacifico, Maria José
Keywords: singular-hyperbolic set | partial hyperbolicity | transitive Anosov flow
An attractor $\Lambda$ for a $3$-vector field $X$ is singular-hyperbolic if all its singularities are hyperbolic and it is partially hyperbolic with volume expanding central direction. We prove that $C^{1+\alpha}$ singular-hyperbolic attractors, for some $\alpha>0$, always have zero volume, thus extending an analogous result for uniformly hyperbolic attractors. The same result holds for a class of higher dimensional singular attractors. Moreover, we prove that if $\Lambda$ is a singular-hyperbolic attractor for $X$ then either it has zero volume or $X$ is an Anosov flow. We also present examples of $C^1$ singular-hyperbolic attractors with positive volume. In addition, we show that $C^1$ generically we have volume zero for $C^1$ robust classes of singular-hyperbolic attractors.