mlsanityData to 7 Oct 2026

Separate Before You Compress: The WWHO Tokenization Architecture

arXiv 2603.25309 ↗First posted 26 Mar 2026cs.CLcited by 0

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Abstract (arXiv)

Current Large Language Models (LLMs) mostly use BPE (Byte Pair Encoding) based tokenizers, which are very effective for simple structured Latin scripts such as English. However, standard BPE tokenizers struggle to process complex Abugida scripts due to their structural complexity. The problem is that these tokenizers break complex conjuncts, which are multi-codepoint grapheme clusters, into meaningless sub-character units. This degrades the LLM's reasoning efficiency by forcing it to learn basic orthographic structures at inference time and raises inference costs, resulting in a significant "Token Tax" for the Global South. We propose a new three-layer architecture, the WWHO (Where-What-How Often), and an algorithm named SGPE (Syllable-aware Grapheme Pair Encoding) that separates the linguistic rules of the script from the statistical compression process while enabling seamless multilingual tokenization. Using Sinhala and Devanagari (Hindi/Sanskrit) as highly complex Abugida scripts, we trained WWHO on a cleaned 30-million-sentence dataset and evaluated on a 1,499,950-sentence test set. For Sinhala, SGPE achieves a Token to Word Ratio (TWR) of 1.274 with 4.83 characters per token, representing a 61.7 percent reduction in tokens compared to OpenAI's o200k base. For Hindi, it achieves a TWR of 1.181 (27.0 percent reduction vs o200k). On the mixed-script (Sinhala, Devanagari, and English) dataset, SGPE achieves an overall TWR of 1.240, representing token reductions of 36.7 percent, 39.6 percent, and 60.2 percent relative to o200k base, Llama 4 Scout, and DeepSeek V3, respectively. This effectively extends the usable context window by up to 4.38 times for these Abugida languages while ensuring a Linguistic Zero-Breakage Guarantee, which ensures that no valid syllable is ever split across multiple tokens.

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References · 10

  1. 2015Neural Machine Translation of Rare Words with Subword Unitscited by 2,898
  2. 2021CANINE: Pre-training an Efficient Tokenization-Free Encoder for Language Representationcited by 229
  3. 2023Language Model Tokenizers Introduce Unfairness Between Languagescited by 207
  4. 2023Do All Languages Cost the Same? Tokenization in the Era of Commercial Language Modelscited by 186
  5. 2023Tokenizer Choice For LLM Training: Negligible or Crucial?cited by 105
  6. 2024Getting the most out of your tokenizer for pre-training and domain adaptationcited by 65
  7. 2024Unpacking Tokenization: Evaluating Text Compression and its Correlation with Model Performancecited by 61
  8. 2019Survey on Publicly Available Sinhala Natural Language Processing Tools and Researchcited by 45
  9. 2024Egalitarian Language Representation in Language Models: It All Begins with Tokenizerscited by 20
  10. 2025SinLlama -- A Large Language Model for Sinhalacited by 8

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