Hugging Face Daily PapersConnor Makowski, Willem Guter1 min readpaperintermediate
The Functionalizer: Lossless Functional Decomposition for Subword Tokenization
Summary
The Functionalizer is a lossless pre‑tokenizer that factors casing, diacritics and character repetitions into reversible opcode prefixes before subword tokenization. Experiments show up to 19.7% smaller vocabularies and a 9.12% syntax‑validity gain on GPT‑2 code models versus standard tokenizers.
- Functionalizer encodes orthographic variations as Unicode Private Use Area opcodes (CAPITALIZE, diacritics, REPEAT, etc.) preceding a canonical base token.
- Vocabulary size drops up to 19.7% while maintaining full corpus coverage, eliminating OOVs under unconstrained exhaustion.
- GPT‑2 models (98 M parameters) trained on Python code see syntax validity rise from 7.70% to 9.12% with Functionalizer.
- The opcode/operand stream is fully reversible, allowing exact reconstruction of the original text.
NLP and code‑model engineers should care because it offers vocab‑efficient, structure‑aware tokenization without sacrificing recoverability.
7/10
