[2] In general systems can be given the ability to reorganize themselves. These are some of the concerns of Distributed Artificial Intelligence (see e.g. [Bond and Gasser, 1988]), but they are outside the scope of this paper.

[3] In the first series of test reported in [Brazdil and Torgo, 1990] the performance gains were somewhat higher than the ones given here. Our previous results were not quite right, however. The problem was caused by a testing method. However, the differences between the two sets of results are not too large.