arXiv Machine Learning
Aug 28

Vowel Signs Are Not Letters: A Pre-tokenization Ceiling on Multilingual Tokenizer Fertility

The paper shows that HuggingFace’s ByteLevel pre‑tokenizer, which treats a word as a sequence of Unicode letters, splits abugida scripts at every vowel sign, creating a training‑free lower bound on tokenizer fertility. Across 26 languages, all 17 abugidas exhibit increased token counts (up to 9×), while Latin, Cyrillic, Hangul, and Han remain unchanged. The authors demonstrate that correcting the character class reduces Nepali token counts, improves model performance, and that this issue is widespread in popular HuggingFace models.

By Sajal Regmi, Siddhartha Pudasaini, Chetan Phakami Pun
arXiv Machine Learning
Oct 3

Universal Byte-Level Encoding: UTF-8/UTF-16 Routing to Reduce Cross-Script Token-Budget Disparities

The paper introduces Universal Byte-Level Encoding (UBE), a dual‑alphabet tokenizer that routes 3‑4‑byte UTF‑8 characters through UTF‑16 while keeping 1‑2‑byte characters on the UTF‑8 path. This design lowers the worst‑case token‑budget disparity for high‑premium scripts without increasing costs for efficient English spans, and it preserves standard BPE merges and exact decoding. In extensive Unicode audits and multilingual language‑model experiments, UBE matches or improves token‑count efficiency and context usability compared to traditional byte‑pair encoding.

By Hyunsik Kim, Youngmoon Jung
arXiv Machine Learning
Aug 21

Auditing Cross-Lingual Fairness in Language Model Watermarking

arXiv:2608. 20047v1 Announce Type: cross Abstract: Watermarking schemes for large language model output are evaluated almost exclusively on English text using each scheme's detection threshold and a narrow set of quality measurements.

By Alexander Nemecek, Osama Zafar, Debargha Ganguly, Vikash Singh, Vipin Chaudhary, Erman Ayday