Pasting together Julia sets: a worked out example of mating.
We prove that the Julia set of a rational map of the Riemann sphere satisfying the Collet-Eckmann condition and having no parabolic periodic point is mean porous, if it is not the whole sphere. It follows that the Minkowski dimension of the Julia set is less than 2.
A connection between iteration theory and the study of sets of commuting holomorphic maps is investigated, in the unit disc of . In particular, given two holomorphic maps and of the unit disc into itself, it is proved that if belongs to the pseudo-iteration semigroup of (in the sense of Cowen) then - under certain conditions on the behaviour of their iterates - the maps and commute.