Parallel Context-of-Experts Decoding for Retrieval Augmented Generation

Giulio Corallo, Paolo Papotti


Abstract
Retrieval Augmented Generation faces a trade-off: concatenating documents in a long prompt enables multi-document reasoning but creates prefill bottlenecks, while encoding document KV caches separately offers speed but breaks cross-document interaction. We propose Parallel Context-of-Experts Decoding (PCED), a training-free framework that shifts evidence aggregation from the attention mechanism to the decoding. PCED treats retrieved documents as isolated "experts", synchronizing their predictions via a retrieval-aware extension of context-aware decoding. This approach recovers cross-document reasoning capabilities without constructing a shared attention across documents.
Anthology ID:
2026.findings-acl.1635
Volume:
Findings of the Association for Computational Linguistics: ACL 2026
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
Findings
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Publisher:
Association for Computational Linguistics
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Pages:
32666–32676
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URL:
https://preview.aclanthology.org/ingest-acl/2026.findings-acl.1635/
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Cite (ACL):
Giulio Corallo and Paolo Papotti. 2026. Parallel Context-of-Experts Decoding for Retrieval Augmented Generation. In Findings of the Association for Computational Linguistics: ACL 2026, pages 32666–32676, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
Parallel Context-of-Experts Decoding for Retrieval Augmented Generation (Corallo & Papotti, Findings 2026)
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https://preview.aclanthology.org/ingest-acl/2026.findings-acl.1635.pdf
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