FedCoT: Communication-Efficient Federated Reasoning Enhancement for Large Language Models

Chuan Li, QianYi Zhao, Fengran Mo, Cen Chen


Abstract
Enhancing LLM reasoning in federated settings is nontrivial due to stringent computational, communication, and privacy constraints, especially in healthcare, where clinically consequential decisions require not only accuracy but also interpretable, auditable rationales to meet safety, accountability, and regulatory requirements. Conventional federated fine-tuning largely imitates final answers rather than cultivating step-by-step reasoning, often relying on privacy-sensitive centralized distillation and still incurring substantial communication overhead. We address this gap with FedCoT, a federated reasoning framework that combines lightweight chain-of-thought resampling with a compact discriminator for selection, and client-aware LoRA stacking with weighted classifier aggregation to accommodate heterogeneity while reducing aggregation noise and communication; clients generate candidate chains and supervision locally, and only lightweight modules are aggregated on the server. Experiments on medical reasoning benchmarks show consistent gains under tight resource budgets while keeping data local and respecting privacy, offering an interpretable and resource-efficient solution.
Anthology ID:
2026.findings-emnlp.127
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
2586–2605
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.127/
DOI:
Bibkey:
Cite (ACL):
Chuan Li, QianYi Zhao, Fengran Mo, and Cen Chen. 2026. FedCoT: Communication-Efficient Federated Reasoning Enhancement for Large Language Models. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 2586–2605, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
FedCoT: Communication-Efficient Federated Reasoning Enhancement for Large Language Models (Li et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.127.pdf