SentencePiece adds Auto-character Coverage as a clean alternative to Byte-Level BPE

prajdabre · x · 2026-09-12

SentencePiece 0.2.3 introduces an "Auto-character Coverage" mode that globally optimizes the character vs. subword budget within a fixed vocabulary via mathematical optimization, avoiding the malformed UTF-8 byte fragments typical of Byte-Level BPE while achieving comparable or better compression. The docs include benchmarks across 13 languages on a 390MB Wikipedia corpus and algorithms for BPE and Unigram models.

Original post →

More from Research

Research channel →