FNet: Mixing Tokens with Fourier Transforms
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Abstract (arXiv)
We show that Transformer encoder architectures can be sped up, with limited accuracy costs, by replacing the self-attention sublayers with simple linear transformations that "mix" input tokens. These linear mixers, along with standard nonlinearities in feed-forward layers, prove competent at modeling semantic relationships in several text classification tasks. Most surprisingly, we find that replacing the self-attention sublayer in a Transformer encoder with a standard, unparameterized Fourier Transform achieves 92-97% of the accuracy of BERT counterparts on the GLUE benchmark, but trains 80% faster on GPUs and 70% faster on TPUs at standard 512 input lengths. At longer input lengths, our FNet model is significantly faster: when compared to the "efficient" Transformers on the Long Range Arena benchmark, FNet matches the accuracy of the most accurate models, while outpacing the fastest models across all sequence lengths on GPUs (and across relatively shorter lengths on TPUs). Finally, FNet has a light memory footprint and is particularly efficient at smaller model sizes; for a fixed speed and accuracy budget, small FNet models outperform Transformer counterparts.
Key facts. Cited by 347 papers in the map (data through 14 Oct 2026). Builds on 52 of its 78 references that are in the map. First posted on arXiv 9 May 2021.
Builds on
52 of 78 references.
References · 52
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Citing papers per year: 2021: 36; 2022: 68; 2023: 67; 2024: 69; 2025: 53; 2026: 54.
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