Genetic/evolutionary methods are frequently used to deal with complex adaptive systems. The classic example is a Genetic
Algorithm. A Genetic Algorithm uses a simple linear representation for possible solutions to a problem. This is usually a bit
vector. Unfortunately, the natural representation for many problems is a tree structure. In order to deal with these types of
problems many evolutionary methods make use of tree structures directly. Gene Expression Programming is a new, popular
evolutionary technique that deals with these types of problems by using a linear representation for trees. In this paper we present
and evaluate Robust Gene Expression Programming (RGEP). This technique is a simplification of Gene Expression
Programming that is equally efficient and powerful. The underlying representation of a solution to a problem in RGEP is a bit
vector as in Genetic Algorithms. It has fewer and simpler operators than those of Gene Expression Programming. We describe
the basic technique, discuss its advantages over related methods, and evaluate its effectiveness on example problems.