Confidence-Calibrated Small-Large Language Model Collaboration for Cost-Efficient Reasoning

Fuente: arXiv
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Main Authors: Zhang, Chuang, Zhu, Zizhen, Wei, Yihao, Tian, Bing, Liu, Junyi, Wang, Henan, Wang, Xavier, Liu, Yaxiao
Format: Preprint
Published: 2026
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author Zhang, Chuang
Zhu, Zizhen
Wei, Yihao
Tian, Bing
Liu, Junyi
Wang, Henan
Wang, Xavier
Liu, Yaxiao
author_facet Zhang, Chuang
Zhu, Zizhen
Wei, Yihao
Tian, Bing
Liu, Junyi
Wang, Henan
Wang, Xavier
Liu, Yaxiao
contents Large language models (LLMs) demonstrate superior reasoning capabilities compared to small language models (SLMs), but incur substantially higher costs. We propose COllaborative REAsoner (COREA), a system that cascades an SLM with an LLM to achieve a balance between accuracy and cost in complex reasoning tasks. COREA first attempts to answer questions using the SLM, which outputs both an answer and a verbalized confidence score. Questions with confidence below a predefined threshold are deferred to the LLM for more accurate resolution. We introduce a reinforcement learning-based training algorithm that aligns the SLM's confidence through an additional confidence calibration reward. Extensive experiments demonstrate that our method jointly improves the SLM's reasoning ability and confidence calibration across diverse datasets and model backbones. Compared to using the LLM alone, COREA reduces cost by 21.5% and 16.8% on out-of-domain math and non-math datasets, respectively, with only an absolute pass@1 drop within 2%.
format Preprint
id arxiv_https___arxiv_org_abs_2603_03752
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Confidence-Calibrated Small-Large Language Model Collaboration for Cost-Efficient Reasoning
Zhang, Chuang
Zhu, Zizhen
Wei, Yihao
Tian, Bing
Liu, Junyi
Wang, Henan
Wang, Xavier
Liu, Yaxiao
Computation and Language
Artificial Intelligence
Large language models (LLMs) demonstrate superior reasoning capabilities compared to small language models (SLMs), but incur substantially higher costs. We propose COllaborative REAsoner (COREA), a system that cascades an SLM with an LLM to achieve a balance between accuracy and cost in complex reasoning tasks. COREA first attempts to answer questions using the SLM, which outputs both an answer and a verbalized confidence score. Questions with confidence below a predefined threshold are deferred to the LLM for more accurate resolution. We introduce a reinforcement learning-based training algorithm that aligns the SLM's confidence through an additional confidence calibration reward. Extensive experiments demonstrate that our method jointly improves the SLM's reasoning ability and confidence calibration across diverse datasets and model backbones. Compared to using the LLM alone, COREA reduces cost by 21.5% and 16.8% on out-of-domain math and non-math datasets, respectively, with only an absolute pass@1 drop within 2%.
title Confidence-Calibrated Small-Large Language Model Collaboration for Cost-Efficient Reasoning
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2603.03752