abstract = "In Genetic Programming (GP), the fitness of
individuals is normally computed by using a set of
fitness cases (FCs). Research on the use of FCs in GP
has primarily focused on how to reduce the size of
these sets. However, often, only a small set of FCs is
available and there is no need to reduce it. In this
work, we are interested in using the whole FCs set, but
rather than adopting the commonly used GP approach of
presenting the entire set of FCs to the system from the
beginning of the search, referred as static FCs, we
allow the GP system to build it by aggregation over
time, named as dynamic FCs, with the hope to make the
search more amenable. Moreover, there is no study on
the use of FCs in Dynamic Optimisation Problems (DOPs).
To this end, we also use the Kendall Tau Distance (KTD)
approach, which quantifies pairwise dissimilarities
among two lists of fitness values. KTD aims to capture
the degree of a change in DOPs and we use this to
promote structural diversity. Results on eight symbolic
regression functions indicate that both approaches are
highly beneficial in GP.",