ModelRefs / Late Interaction (ColBERT) — AI Glossary

Late Interaction (ColBERT) — AI Glossary

A retrieval architecture encoding query and document tokens separately, computing fine-grained token-level similarity at query time.

Overview

ColBERT (Khattab & Zaharia 2020) stores per-token embeddings for every document. At query time, each query token finds its best-matching document token (MaxSim). Late interaction achieves near cross-encoder quality with much faster search (ANN on token embeddings). ColBERT-v2 adds compression; RAGatouille provides a simple Python wrapper.

Reference details

Topicrag
Also known asColBERT, token-level interaction
Last reviewed2026-06-24

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Frequently asked questions

What is Late Interaction (ColBERT)?

A retrieval architecture encoding query and document tokens separately, computing fine-grained token-level similarity at query time.

Is Late Interaction (ColBERT) the same as ColBERT?

Yes — ColBERT, token-level interaction are common aliases for Late Interaction (ColBERT).

What concepts are related to Late Interaction (ColBERT)?

Closely related concepts include bi encoder, dense retrieval, reranking.