Retrieval-augmented reasoning with lean language models

Fuente: arXiv
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Main Authors: Chan, Ryan Sze-Yin, Nanni, Federico, Lazauskas, Tomas, Wood, Rosie, Yong, Penelope, Tarassenko, Lionel, Girolami, Mark, Geddes, James, Duncan, Andrew
Format: Preprint
Published: 2025
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author Chan, Ryan Sze-Yin
Nanni, Federico
Lazauskas, Tomas
Wood, Rosie
Yong, Penelope
Tarassenko, Lionel
Girolami, Mark
Geddes, James
Duncan, Andrew
author_facet Chan, Ryan Sze-Yin
Nanni, Federico
Lazauskas, Tomas
Wood, Rosie
Yong, Penelope
Tarassenko, Lionel
Girolami, Mark
Geddes, James
Duncan, Andrew
contents This technical report details a novel approach to combining reasoning and retrieval augmented generation (RAG) within a single, lean language model architecture. While existing RAG systems typically rely on large-scale models and external APIs, our work addresses the increasing demand for performant and privacy-preserving solutions deployable in resource-constrained or secure environments. Building on recent developments in test-time scaling and small-scale reasoning models, we develop a retrieval augmented conversational agent capable of interpreting complex, domain-specific queries using a lightweight backbone model. Our system integrates a dense retriever with fine-tuned Qwen2.5-Instruct models, using synthetic query generation and reasoning traces derived from frontier models (e.g., DeepSeek-R1) over a curated corpus, in this case, the NHS A-to-Z condition pages. We explore the impact of summarisation-based document compression, synthetic data design, and reasoning-aware fine-tuning on model performance. Evaluation against both non-reasoning and general-purpose lean models demonstrates that our domain-specific fine-tuning approach yields substantial gains in answer accuracy and consistency, approaching frontier-level performance while remaining feasible for local deployment. All implementation details and code are publicly released to support reproducibility and adaptation across domains.
format Preprint
id arxiv_https___arxiv_org_abs_2508_11386
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Retrieval-augmented reasoning with lean language models
Chan, Ryan Sze-Yin
Nanni, Federico
Lazauskas, Tomas
Wood, Rosie
Yong, Penelope
Tarassenko, Lionel
Girolami, Mark
Geddes, James
Duncan, Andrew
Computation and Language
Artificial Intelligence
Computers and Society
This technical report details a novel approach to combining reasoning and retrieval augmented generation (RAG) within a single, lean language model architecture. While existing RAG systems typically rely on large-scale models and external APIs, our work addresses the increasing demand for performant and privacy-preserving solutions deployable in resource-constrained or secure environments. Building on recent developments in test-time scaling and small-scale reasoning models, we develop a retrieval augmented conversational agent capable of interpreting complex, domain-specific queries using a lightweight backbone model. Our system integrates a dense retriever with fine-tuned Qwen2.5-Instruct models, using synthetic query generation and reasoning traces derived from frontier models (e.g., DeepSeek-R1) over a curated corpus, in this case, the NHS A-to-Z condition pages. We explore the impact of summarisation-based document compression, synthetic data design, and reasoning-aware fine-tuning on model performance. Evaluation against both non-reasoning and general-purpose lean models demonstrates that our domain-specific fine-tuning approach yields substantial gains in answer accuracy and consistency, approaching frontier-level performance while remaining feasible for local deployment. All implementation details and code are publicly released to support reproducibility and adaptation across domains.
title Retrieval-augmented reasoning with lean language models
topic Computation and Language
Artificial Intelligence
Computers and Society
url https://arxiv.org/abs/2508.11386