  We propose an extension of the concept of algebraic entropy, as introduced by
Bellon and Viallet for rational maps, to algebraic maps (or correspondences) of
a certain kind. The corresponding entropy is an index of the complexity of the
map. The definition inherits the basic properties from the definition of
entropy for rational maps. We give an example with positive entropy, as well as
two examples taken from the theory of Backlund transformations.
