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Saturday, 31 October 2026 · Weekend classic from 2020 · 5 min read

Combining retrieval and generation improves knowledge-intensive NLP tasks

RAG models integrate a pre-trained seq2seq generator with a neural retriever over Wikipedia, achieving state-of-the-art results on open-domain QA and generating more factual, diverse text than parametric-only baselines.

Based on the paper Retrieval-Augmented Generation for Knowledge-Intensive NLP Tasks by Patrick Lewis, Ethan Perez, Aleksandra Piktus, Fabio Petroni and 8 others

Challenges in knowledge-intensive NLP and limitations of parametric models

Large pre-trained language models store factual knowledge in their parameters and perform well on many NLP tasks, but they struggle to precisely access and manipulate knowledge for knowledge-intensive tasks.

Such models cannot easily update their knowledge or provide provenance for their outputs, and they sometimes hallucinate incorrect facts.

Hybrid models that combine parametric memory with retrieval-based non-parametric memory can address these issues by allowing direct access to external knowledge sources, but prior work has focused mainly on extractive QA tasks rather than general generation.

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Combining retrieval and generation improves knowledge-intensive NLP tasks · Bezen