abstract = "In evolutionary computation approaches such as genetic
programming (GP), preventing premature convergence to
local minima is known to improve performance. As with
other evolutionary computation methods, it can be
difficult to construct an effective search bias in GP
that avoids local minima. In particular, it is
difficult to determine which features are the most
suitable for the search bias, because GP solutions are
expressed in terms of trees and have multiple features.
A common approach intended to local minima is known as
the Island Model. This model generates multiple
populations to encourage a global search and enhance
genetic diversity. To improve the Island Model in the
framework of GP, we propose a novel technique using a
migration strategy based on textit frequent trees and a
local search, where the frequent trees refer to
subtrees that appear multiple times among the
individuals in the island. The proposed method
evaluates each island by measuring its activation level
in terms of the fitness value and how many types of
frequent trees have been created. Several individuals
are then migrated from an island with a high activation
level to an island with a low activation level, and
vice versa. The proposed method also combines strong
partial solutions given by a local search. Using six
kinds of benchmark problems widely adopted in the
literature, we demonstrate that the incorporation of
frequent tree information into a migration strategy and
local search effectively improves performance. The
proposed method is shown to significantly outperform
both a typical Island Model GP and the aged layered
population structure method.",
notes = "The Journal of Polish Neural Network Society, the
University of Social Sciences in Lodz & Czestochowa
University of Technology