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Artificial Life

Fall 2001, Vol. 7, No. 4, Pages 395-418
(doi: 10.1162/106454601317297022)
© 2002 Massachusetts Institute of Technology
Comparison of Different Genotype Encodings for Simulated Three-Dimensional Agents
Article PDF (2.07 MB)

We analyze the effect of different genetic encodings used for evolving three-dimensional agents with physical morphologies. The complex phenotypes used in such systems often require nontrivial encodings. Different encodings used in Framsticks—a system for evolving three-dimensional agents—are presented. These include a low-level direct mapping and two higher-level encodings: one recurrent and one developmental. Quantitative results are presented from three simple optimization tasks (passive height, active height, and locomotion speed). The low-level encoding produced solutions of lower fitness than the two higher-level encodings under similar conditions. Results from recurrent and developmental encodings had similar fitness values but displayed qualitative differences. Desirable advantages and some drawbacks of more complex encodings are established.