abstract = "Can symmetry be used as a design principle to
constrain evolutionary search, making it more
effective? This dissertation aims to show that this is
indeed the case, in two ways. First, an approach called
ENSO is developed to evolve modular neural network
controllers for simulated multilegged robots. Inspired
by how symmetric organisms have evolved in nature, ENSO
uses group theory to break symmetry systematically,
constraining evolution to explore promising regions of
the search space. As a result, it evolves effective
controllers even when the appropriate symmetry
constraints are difficult to design by hand. The
controllers perform equally well when transferred from
simulation to a physical robot. Second, the same
principle is used to evolve minimal-size sorting
networks. In this different domain, a different
instantiation of the same principle is effective:
building the desired symmetry step-by-step. This
approach is more scalable than previous methods and
finds smaller networks, thereby demonstrating that the
principle is general. Thus, evolutionary search that
uses symmetry constraints is shown to be effective in a
range of challenging applications.",