让推理更可信,同时不损失回答准确率。
Does Faithfulness-Guided Alignment Hurt Accuracy? Unlocking Accurate and Faithful Post-Retrieval Reasoning
- 用可配置审计性的结构化推理链,结合格式、答案、引用和语义忠实度奖励。
- 1.5B以上模型在多跳问答中准确率与可信度双提升,7B模型超越基线且媲美闭源模型。
- 适合需要可解释、可审计推理的场景,如医疗、法律等高风险领域。
检索增强生成(RAG)在多跳问题上可实现高回答准确率,但结果层面的奖励常导致推理过程缺乏事实依据,难以审计。在噪声检索下,模型可能出现‘答对理错’的情况:答案正确但推理依赖捷径或无支持证据。本文探讨可信度引导对准确率的影响,提出CRAFT(校准推理与答案忠实轨迹),一个用于检索后多跳问答生成阶段的强化学习框架。CRAFT训练模型生成可配置审计性的结构化推理链,结合确定性奖励(格式合规、答案正确、引用有效)与基于评判者的语义可信度奖励。跨模型规模与基准测试显示,CRAFT在1.5B及以上模型中释放出任务特定推理能力,同时提升准确率与可信度;0.5B模型性能仍高度依赖模板。7B模型在所有评估设置下均显著提升可信度,且与强闭源模型竞争。代码已开源。
原文摘要 · Abstract (English)
Retrieval-augmented generation (RAG) can achieve strong answer accuracy on multi-hop questions, but outcome-level rewards often leave reasoning traces weakly grounded and difficult to audit. Under noisy retrieval, models may exhibit right-answer-wrong-reason failures, where the final answer is correct but the supporting rationale exploits shortcuts or unsupported evidence. We therefore ask whether faithfulness-guided alignment hurts answer accuracy in post-retrieval reasoning. To study this question, we propose CRAFT (Calibrated Reasoning with Answer-Faithful Traces), a reinforcement learning framework for the response-generation stage of retrieval-augmented multi-hop question answering. CRAFT trains models to produce structured reasoning traces with configurable auditability, while combining deterministic rewards for format compliance, answer correctness, and citation validity with a judge-based reward for semantic faithfulness. Experiments across model scales and benchmarks show that CRAFT unlocks task-specific reasoning capacity from 1.5B upward, improving both answer accuracy and Faithfulness; at 0.5B, performance remains sharply template-dependent. At 7B, CRAFT improves Faithfulness over the Base model in all evaluated settings and remains competitive with strong closed-source models. Code is available at https://github.com/Ameame1/CRAFT.
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