abstract = "The size of the search space has been analysed for
genetic programming and genetic algorithms. It is
highly unlikely to find any single individual in this
huge search space. However, genetic programming with
variable length structures differs from standard
genetic algorithms where fixed size bit strings are
used in that usually many different individuals show
the same pheno-typical behaviour due to introns.
Therefore, finding any given behaviour is not as
difficult as the size of the search space suggests. A
quantitative analysis is presented for the number of
individuals that code for the identity function. The
identity function is important in the analysis of the
search space because it can be used to construct
individuals showing the same behavior as any given
individual. Finally, an analogy is drawn to nature's
sequence space which suggests possible directions for
future research. The representation should be chosen
such that all possible behaviours are reachable within
a comparatively small number of steps from any given
behaviour and the individuals coding for any given
behaviour should be distributed randomly in the search
space. In addition, long paths of neutral mutations
should lead to individuals which code for the same
behaviour",
notes = "CEC-99 - A joint meeting of the IEEE, Evolutionary
Programming Society, Galesia, and the IEE.