“…With the prior knowledge about typical properties of architectures, NAS approaches commonly define the searching space as a large set of operations (e.g., convolution, fully-connected, and pooling). Each possible architecture in the searching space is evaluated by a certain evaluation strategy [32], [33] and the searching process is controlled by certain searching algorithms, such as reinforcement learning [33], [35], [36], evolutionary search [37], differentiable search [38], or other learning algorithms [34], [39], [40], [41]. NAS commonly defines a searching space at first and then uses a certain policy to generate a sequence of actions in the searching space to specify the architecture.…”