Editing Gene expression programming (section)

====Mutation====
In gene expression programming mutation is the most important genetic operator.<ref>{{cite web|last=Ferreira|first=C.|year=2002|title=Mutation, Transposition, and Recombination: An Analysis of the Evolutionary Dynamics|url= http://www.gene-expression-programming.com/webpapers/ferreira-fea02.pdf|publisher=  In H. J. Caulfield, S.-H. Chen, H.-D. Cheng, R. Duro, V. Honavar, E. E. Kerre, M. Lu, M. G. Romay, T. K. Shih, D. Ventura, P. P. Wang, Y. Yang, eds., Proceedings of the 6th Joint Conference on Information Sciences, 4th International Workshop on Frontiers in Evolutionary Algorithms, pages 614–617, Research Triangle Park, North Carolina, USA}}</ref> It changes genomes by changing an element by another. The accumulation of many small changes over time can create great diversity.

In gene expression programming mutation is totally unconstrained, which means that in each gene domain any domain symbol can be replaced by another. For example, in the heads of genes any function can be replaced by a terminal or another function, regardless of the number of arguments in this new function; and a terminal can be replaced by a function or another terminal.