  The renaissance of neural architecture search (NAS) has seen classical
methods such as genetic algorithms (GA) and genetic programming (GP) being
exploited for convolutional neural network (CNN) architectures. While recent
work have achieved promising performance on visual perception tasks, the direct
encoding scheme of both GA and GP has functional complexity deficiency and does
not scale well on large architectures like CNN. To address this, we present a
new generative encoding scheme -- $symbolic\ linear\ generative\ encoding$
(SLGE) -- simple, yet powerful scheme which embeds local graph transformations
in chromosomes of linear fixed-length string to develop CNN architectures of
variant shapes and sizes via evolutionary process of gene expression
programming. In experiments, the effectiveness of SLGE is shown in discovering
architectures that improve the performance of the state-of-the-art handcrafted
CNN architectures on CIFAR-10 and CIFAR-100 image classification tasks; and
achieves a competitive classification error rate with the existing NAS methods
using less GPU resources.
