LayerNAS: Neural Architecture Search in Polynomial Complexity

Neural Architecture Search (NAS) has become a popular method for discovering effective model architectures, especially for target hardware. As such, NAS methods that find optimal architectures under constraints are essential. In our paper, we propose LayerNAS to address the challenge of multi-objective NAS by transforming it into a combinatorial optimization problem, which effectively constrains the search complexity to be polynomial. For a model architecture with $L$ layers, we perform layerwise-search for each layer, selecting from a set of search options $\mathbb{S}$. LayerNAS groups model candidates based on one objective, such as model size or latency, and searches for the optimal model based on another objective, thereby splitting the cost and reward elements of the search. This approach limits the search complexity to $ O(H \cdot |\mathbb{S}| \cdot L) $, where $H$ is a constant set in LayerNAS. Our experiments show that LayerNAS is able to consistently discover superior models across a variety of search spaces in comparison to strong baselines, including search spaces derived from NATS-Bench, MobileNetV2 and MobileNetV3.

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Task Dataset Model Metric Name Metric Value Global Rank Result Benchmark
Neural Architecture Search ImageNet LayerNAS-600M Top-1 Error Rate 21.4 # 44
Params 9.7M # 7
MACs 627M # 132
Neural Architecture Search ImageNet LayerNAS-60M Top-1 Error Rate 31 # 129
Params 3.7M # 55
MACs 61M # 66
Neural Architecture Search ImageNet LayerNAS-220M Top-1 Error Rate 24.4 # 103
Params 5.1M # 41
MACs 229M # 77
Neural Architecture Search ImageNet LayerNAS-300M Top-1 Error Rate 22.9 # 72
Params 5.2M # 39
MACs 322M # 95
Neural Architecture Search NAS-Bench-101 LayerNAS Accuracy (%) 94.26% # 2
Neural Architecture Search NATS-Bench Size, CIFAR-10 LayerNAS Test Accuracy 93.2 # 1
Validation Accuracy 0.844 # 1
Neural Architecture Search NATS-Bench Size, CIFAR-100 LayerNAS Test Accuracy 70.64 # 1
Validation Accuracy 60.67 # 1
Neural Architecture Search NATS-Bench Size, ImageNet16-120 LayerNAS Validation Accuracy 38.12 # 1
Test Accuracy 45.37 # 1
Neural Architecture Search NATS-Bench Topology, CIFAR-10 LayerNAS Test Accuracy 94.34±0.12 # 1
Neural Architecture Search NATS-Bench Topology, CIFAR-100 LayerNAS Test Accuracy 73.01±0.63 # 1
Neural Architecture Search NATS-Bench Topology, ImageNet16-120 LayerNAS Test Accuracy 46.58±0.59 # 1

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