Hausdorff dimension of limit sets

We exhibit a class of Schottky subgroups of () which we call well-positioned and show that the Hausdorff dimension of the limit set associated with such a subgroup , with respect to the spherical metric on the boundary of complex hyperbolic n-space, is equal to the growth exponent . For general we establish (under rather mild hypotheses) a lower bound involving the dimension of the Patterson-Sullivan measure along boundaries of complex geodesics. Our main tool is a version of the celebrated Ledrappier-Young theorem.