abstract = "The standard crossover operator in tree-based Genetic
Programming (GP) is problematic in that it is most
often destructive. Selecting crossover points with an
implicit bias towards the leaves of a program tree
aggravates its destructiveness and causes the code
bloat problem in GP. Therefore, a common view has been
developed that adjusting the depth of crossover points
to eliminate the bias can improve GP performance, and
many attempts have been made to create effective
crossover operators according to this view. As there
are a large number of possible depth-control
strategies, it is very difficult to identify the
strategy that provides the most significant improvement
in performance. This paper explores depth-control
strategies by analysing the depth of crossover points
in evolutionary process logs of five different GP
systems on problems in three different domains. It
concludes that controlling the depth of crossover
points is an evolutionary stage dependent and problem
dependent task, and obtaining a significant performance
improvement is not trivial.",
notes = "CEC 2007 - A joint meeting of the IEEE, the EPS, and
the IET.