abstract = "Symbolic regression is aimed at discovering
mathematical expressions, in symbolic form, that fit a
given sample of data points. While Genetic Programming
(GP) constitutes a powerful tool for solving this class
of problems, its effectiveness is still severely
limited when the data sample requires different
expressions in different regions of the input space -
i.e., when the approximating function should be
discontinuous. In this paper we present a new GP-based
approach for symbolic regression of discontinuous
functions in multivariate data-sets. We identify the
portions of the input space that require different
approximating functions by means of a new algorithm
that we call Hyper-Volume Error Separation (HVES). To
this end we run a preliminary GP evolution and
partition the input space based on the error exhibited
by the best individual across the data-set. Then we
partition the data-set based on the partition of the
input space and use each such partition for driving an
independent, preliminary GP evolution. The populations
resulting from such preliminary evolutions are finally
merged and evolved again. We compared our approach to
the standard GP search and to a GP search for
discontinuous functions in univariate data-sets. Our
results show that coupling HVES with GP is an effective
approach and provides significant accuracy improvements
while requiring less computational resources.",
notes = "CEC 2007 - A joint meeting of the IEEE, the EPS, and
the IET.