Introduction
Every architecture in this course, from ResNet to the transformer, was designed by people: trying ideas, running experiments, keeping what worked. Neural architecture search (NAS) automates part of this: an algorithm explores many possible architectures and finds ones that perform well, sometimes better than human designs.
Several well-known models were found or refined this way: NASNet, AmoebaNet, EfficientNet's baseline (B0) and MobileNetV3 (Computer Vision tab, topic 2.4).
Think of designing a new recipe. A chef can taste and adjust by intuition. Alternatively, a kitchen robot could systematically try thousands of ingredient combinations and cooking times, keeping the best-rated dishes. NAS is the robot. The challenges are the same: what combinations are allowed (the search space), how to choose what to try next (the search strategy), and how to rate each dish quickly (performance estimation).