Decoder. plain-English AI glossary

Deduplication

● Core

Removing repeated or near-identical examples from a dataset before training.

Think of it like

Like clearing duplicate photos off your phone so one over-shared meme doesn’t crowd out your actual memories.

Example

A web crawl has the same article mirrored a thousand times; dedup keeps one copy so the model doesn’t over-weight it.

How it actually works

Large corpora are full of exact and near-duplicate text, and training on repeats wastes compute, encourages memorization, and can worsen contamination. Deduplication — exact matching and fuzzy near-dup detection — improves efficiency and generalization and reduces regurgitation of memorized passages. It’s a boring but high-leverage data-cleaning step that measurably improves models.

For product teams

A cheap data-hygiene step that makes models train faster and memorize less — quietly important.

For engineers

Exact/near-duplicate removal from corpora; cuts memorization and contamination, improves training efficiency.

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