Zusammenfassung
Standard Genetic Programming operators are highly
disruptive, with the concomitant risk that it may be
difficult to converge to an optimal structure. The Tree
Adjoining Grammar (TAG) formalism provides a more
flexible Genetic Programming tree representation which
supports a wide range of operators while retaining the
advantages of tree-based representation. In particular,
minimal-change point insertion and deletion operators
may be defined. Previous work has shown that point
insertion and deletion, used as local search operators,
can dramatically reduce search effort in a range of
standard problems. Here, we evaluate the effect of
local search with these operators on a real-World
ecological time series modelling problem. For the same
search effort, TAG-based GP with the local search
operators generates solutions with significantly lower
training set error. The results are equivocal on test
set error, local search generating larger individuals
which generalise only a little better than the less
accurate solutions given by the original algorithm.
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