Methods to estimate the Hausdorff dimension of invariant sets of scattering
systems are presented. Based on the levels' hierarchical structure of the time
delay function, these techniques can be used in systems whose
future-invariant-set codimensions are approximately equal to or greater than
one. The discussion is illustrated by a numerical example of a scatterer built
with four hard spheres located at the vertices of a regular tetrahedron.Comment: 9 pages, 5 figures, accepted in Physics Letters
