I would like to present some result concerning packing and
Hausdorff dimension for nonconformal repellers in the plane.
I'll start from some background material and basic facts which allow to
estimate packing dimension
in terms of Lapunov exponents and/or the zeros of pressure functions
(Bowen-Ruelle formula).
Then I'll give a proof of sharp estimate
HD(J)>h/λ where h is metric entropy and λ is the
smallest Lapunov exponent for a given Gibbs measure μ.