Abstract
Grammatical evolution (GE) is a kind of new evolutionary algorithms. It is related to the idea of genetic programming in that the objective is to find an executable program or program fragment that will achieve a good fitness value for the given objective function to be minimized. Therefore, the search algorithm of GE is very similar to Genetic algorithm (GA) except for the translation rules. In the GE, the translation rules from genotype (bit string) to phenotype (function or program) are defined according to the Backus-Naur form (BNF). The rules are applied for estimating fitness functions. In this study, an original GE and three improved algorithms are applied for predicting the constitutive equation in the plane strain state. The numerical results show the convergence speed of the improved algorithm is faster than the original GE.
