Neural Architecture Search based on Cartesian Genetic Programming Coding Method

Neural architecture search (NAS) is a hot topic in the field of automated machine learning (AutoML) and has begun to outperform human-designed architectures on many machine learning tasks. Motivated by the natural representation form of neural networks by the Cartesian genetic programming (CGP), we propose an evolutionary approach of NAS based on CGP, called CPGNAS, to solve sentence classification task. To evolve the architectures under the framework of CGP, the existing key operations are identified as the types of function nodes of CGP, and the evolutionary operations are designed based on evolutionary strategy (ES). The experimental results show that the searched architecture can reach the accuracy of human-designed architectures. The ablation tests identify the Attention function as the single key function node and the Convolution and Attention as the joint key function nodes. However, the linear transformations along could keep the accuracy of evolved architectures over 70%, which is worthy of investigation in the future.