  We study two notions of topological entropy of correspondences introduced by
Friedland and Dinh-Sibony. Upper bounds are known for both. We identify a class
of holomorphic correspondences whose entropy in the sense of Dinh-Sibony equals
the known upper bound. This provides an exact computation of the entropy for
rational semigroups. We also explore a connection between these two notions of
entropy.

Dynamical Systems;Complex Variables