  Neural Networks design is a complex and often daunting task, particularly for
resource-constrained scenarios typical of mobile-sized models. Neural
Architecture Search is a promising approach to automate this process, but
existing competitive methods require large training time and computational
resources to generate accurate models. To overcome these limits, this paper
contributes with: i) a novel training-free metric, named Entropic Score, to
estimate model expressivity through the aggregated element-wise entropy of its
activations; ii) a cyclic search algorithm to separately yet synergistically
search model size and topology. Entropic Score shows remarkable ability in
searching for the topology of the network, and a proper combination with
LogSynflow, to search for model size, yields superior capability to completely
design high-performance Hybrid Transformers for edge applications in less than
1 GPU hour, resulting in the fastest and most accurate NAS method for ImageNet
classification.
