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Applications of thermodynamic formalism in complex dynamics on $\mathbb{P}^2$
In this paper, we review several notions from thermodynamic formalism,
like topological pressure and entropy and show how they can be employed, in order
to obtain information about stable and unstable sets of holomorphic endomorphisms
of $\mathbb P^2$ with Axiom A.
In particular, we will consider the non-wandering set of such a mapping and its
"saddle" part $S_1$, i.e the subset of points with both stable and unstable directions.
Under a derivative condition, the stable manifolds of points in S1 will have a very
"thin" intersection with $S_1$, from the point of view of Hausdorff dimension. While
for diffeomorphisms there is in fact an equality between
$HD(W^s_\varepsilon(x)\cap S_1)$ and the
unique zero of $P(t \cdot \phi^s)$ (Verjovsky-Wu [VW]) in the case of endomorphisms this will
not be true anymore; counterexamples in this direction will be provided. We also
prove that the unstable manifolds of an endomorphism depend
Hölder continuously
on the corresponding prehistory of their base point and employ this in the end to
give an estimate of the Hausdorff dimension of the global unstable set of $S_1$. This
set could be à priori very large, since, unlike in the case of H´enon maps, there is an
uncountable collection of local unstable manifolds passing through each point of $S_1$.