Papers › BPE Gets Picky: Efficient Vocabulary Refinement During Tokenizer Training

BPE Gets Picky: Efficient Vocabulary Refinement During Tokenizer Training

6 Sep 2024arXiv:2409.04599archive 2025-07-28

Pavel Chizhov, Catherine Arnett, Elizaveta Korotkova, Ivan P. Yamshchikov

Language models can largely benefit from efficient tokenization. However, they still mostly utilize the classical BPE algorithm, a simple and reliable method. This has been shown to cause such issues as under-trained tokens and sub-optimal compression that may affect the downstream performance. We introduce Picky BPE, a modified BPE algorithm that carries out vocabulary refinement during tokenizer training. Our method improves vocabulary efficiency, eliminates under-trained tokens, and does not compromise text compression. Our experiments show that our method does not reduce the downstream performance, and in several cases improves it.

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Text Compression

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BPE

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