  The simultaneous evolution of two or more species with coupled fitness --
coevolution -- has been put to good use in the field of evolutionary
computation. Herein, we present two new forms of coevolutionary algorithms,
which we have recently designed and applied with success. OMNIREP is a
cooperative coevolutionary algorithm that discovers both a representation and
an encoding for solving a particular problem of interest. SAFE is a
commensalistic coevolutionary algorithm that maintains two coevolving
populations: a population of candidate solutions and a population of candidate
objective functions needed to measure solution quality during evolution.
