AZ-NAS: Assembling Zero-Cost Proxies for Network Architecture Search

Training-free network architecture search (NAS) aims to discover high-performing networks with zero-cost proxies capturing network characteristics related to the final performance. However network rankings estimated by previous training-free NAS methods have shown weak correlations with the performance. To address this issue we propose AZ-NAS a novel approach that leverages the ensemble of various zero-cost proxies to enhance the correlation between a predicted ranking of networks and the ground truth substantially in terms of the performance. To achieve this we introduce four novel zero-cost proxies that are complementary to each other analyzing distinct traits of architectures in the views of expressivity progressivity trainability and complexity. The proxy scores can be obtained simultaneously within a single forward and backward pass making an overall NAS process highly efficient. In order to integrate the rankings predicted by our proxies effectively we introduce a non-linear ranking aggregation method that highlights the networks highly-ranked consistently across all the proxies. Experimental results conclusively demonstrate the efficacy and efficiency of AZ-NAS outperforming state-of-the-art methods on standard benchmarks all while maintaining a reasonable runtime cost.