🔤 Tokenizer Comparison

Compare BPE, WordPiece, SentencePiece, and Unigram tokenization methods

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Language Model Scaling Laws

Introduction to Tokenization

🎯 Why Tokenization Matters

Tokenization converts text into discrete units that language models can process. The choice of tokenizer impacts vocabulary size, model efficiency, and multilingual performance.

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Key Insight

Subword tokenization balances vocabulary size with coverage, enabling models to handle rare words and new languages efficiently.

📝
Word-Level

Simple but huge vocabulary. Struggles with rare words and morphology.

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Character-Level

Small vocabulary but long sequences. Loses semantic meaning.

Subword-Level

Optimal balance: moderate vocabulary, handles rare words, preserves meaning.

🏆 Major Tokenizers in Use

BPE (Byte-Pair Encoding)GPT, GPT-2, GPT-3

Merges frequent character pairs iteratively. Simple and effective.

WordPieceBERT, DistilBERT

Similar to BPE but uses likelihood-based scoring. Common in Google models.

SentencePieceT5, XLNet, LLaMA

Language-agnostic, treats text as raw UTF-8. Excellent for multilingual.

UnigramAlBERT, mBART

Probabilistic model that finds optimal subword vocabulary.

✅ Benefits

  • Handle unlimited vocabulary with fixed size
  • Better compression than word-level
  • Capture morphological patterns

⚠️ Trade-offs

  • Vocabulary size impacts memory
  • Different tokenizers not interchangeable
  • Longer sequences for some languages