Why can the BIOES tag scheme (Begin, Inside, Other, End, Single) work better than BIO for NER?

Question

Accepted Answer

The richer tag set gives the CRF more precise transition constraints to learn

Accepted Answer

It marks the end of entities explicitly, giving the model stronger signals at boundaries

Accepted Answer

Single-word entities get their own S- tag, avoiding confusion with multi-word entities

Answer

BIOES has fewer tags than BIO, making it simpler

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