abstract = "This paper investigates the effect on building blocks
during evolution of two online program simplification
methods in genetic programming. The two simplification
methods considered are algebraic simplification and
numerical simplification. The building blocks
considered are of a more general form (two and three
level subtrees) than numeric constants only. Unlike
most of the existing work which often uses simple
symbolic regression tasks, this work considers
classification tasks as examples. We develop a new
method for encoding possible building blocks for the
analysis. The results show that the two online program
simplification methods can generate new diverse
building blocks during evolution although they also
destroy existing ones and that many of the existing
building blocks are retained during evolution. Compared
with the canonical genetic programming method, the two
simplification methods can generate much smaller
programs, use much shorter evolutionary training time
and achieve comparable effectiveness performance.",
notes = "GECCO-2009 A joint meeting of the eighteenth
international conference on genetic algorithms
(ICGA-2009) and the fourteenth annual genetic
programming conference (GP-2009).