Here are some links about the specific algorithm in CSALT used:

http://blog.nutonian.com/bid/312708/Setting-and-using-validation-data-with-Eureqa (random?)

http://formulize.nutonian.com/forum/discussion/555/training-validation-and-test-sets/p1

https://groups.google.com/forum/#!msg/eureqa-group/LlryhZTjqgs/P-EAivy61NsJ