Research map / Large language models / Retrieval and knowledge
KnowPO: Knowledge-Aware Preference Optimization for Controllable Knowledge Selection in Retrieval-Augmented Language Models
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Proposes KnowPO, a DPO-based preference optimization with SFT that teaches RAG models to follow conflicting context and ignore irrelevant context, using constructed contextual-ignorance and contextual-overinclusion negative samples plus length and error-ratio balancing.
Problem
LLMs in retrieval-augmented generation balance poorly between adherence to conflicting external knowledge and robustness to irrelevant noisy context; instruction tuning alone lacks explicit negative signals, leading to contextual ignorance and contextual overinclusion.
Approach
Builds knowledge-conflict preference pairs (conflicting vs. irrelevant contexts, with error-type negatives generated by GPT-4), aligns response lengths and balances the two error-type pair ratios (R_error=1), and trains with LoRA DPO after an instruction-tuning SFT stage.
Key results
- On SQuAD2.0-Eval with Baichuan2-7B-Chat, KnowPO reaches R_Ad 80.64% and R_Ro 38.77%, versus 58.83% and 21.43% for the best baseline KAFT.
- On RGB with Llama2-13B-Chat, KnowPO reaches R_Ad 83.50% and R_Ro 37.50%, and on KNOT R_Ad 77.03% and R_Ro 38.28%.
- On CMB medical test set, KnowPO improves Baichuan2-7B-Chat R_Ad from 58.69% to 96.23% and R_Ro from 10.66% to 24.12%.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| train with KnowPO instead of KAFT | Baichuan2-7B-Chat · SQuAD2.0-Eval | R_Ad: 58.83$\pm$0.72 -> 80.64$\pm$0.36 | Helped |
| train with KnowPO instead of KAFT | Baichuan2-7B-Chat · RGB | R_Ro: 27.00$\pm$0.45 -> 37.00$\pm$0.31 | Helped |
| train with KnowPO instead of KAFT | Llama2-13B-Chat · KNOT | R_Ad: 62.21$\pm$0.51 -> 77.03$\pm$0.33 | Helped |
| add DPO training (ablation) | KnowPO on Baichuan2-7B-Chat · SQuAD2.0-Eval | R_Ad: 71.09$\pm$0.30 -> 80.64$\pm$0.36 | Helped |
| add DPO training (ablation) | KnowPO on Llama2-13B-Chat · SQuAD2.0-Eval | R_Ro: 42.87$\pm$1.06 -> 44.64$\pm$0.30 | Helped |
| add SFT (ablation) | KnowPO on Baichuan2-7B-Chat · SQuAD2.0-Eval | R_Ad: 69.39$\pm$0.67 -> 80.64$\pm$0.36 | Helped |
| add response-length alignment (ablation) | KnowPO on Baichuan2-7B-Chat · SQuAD2.0-Eval | R_Ad: 54.45$\pm$0.51 -> 80.64$\pm$0.36 | Helped |
| add response-length alignment (ablation) | KnowPO on Baichuan2-7B-Chat · SQuAD2.0-Eval | R_Ro: 43.45$\pm$0.62 -> 38.77$\pm$0.42 | Hurt |
| add response-length alignment (ablation) | KnowPO on Llama2-13B-Chat · SQuAD2.0-Eval | R_Ad: 61.36$\pm$0.94 -> 76.11$\pm$0.37 | Helped |
| add response-length alignment (ablation) | KnowPO on Llama2-13B-Chat · SQuAD2.0-Eval | R_Ro: 50.30$\pm$0.94 -> 44.64$\pm$0.30 | Hurt |
| set preference-pair ratio R_error to 1 (ablation) | KnowPO on Baichuan2-7B-Chat · SQuAD2.0-Eval | R_Ad and R_Ro balance | Helped |
| increase contextual-ignorance preference pairs relative to contextual-overinclusion pairs (ablation) | KnowPO · SQuAD2.0-Eval | R_Ad | Helped |
Surprising findings
- Length imbalance between preferred and dispreferred responses biased DPO toward verbose refusals, substantially reducing adherence when lengths were not aligned.
- Counterfactual answers were not required to be correct; only the conflict between the parametric and context answer mattered.
Limitations
- Relies on GPT-4 to generate counterfactual and contextual-overinclusion negatives, and the evaluation uses constructed contexts that the authors say are less challenging than real RAG contexts.
- Evaluated on only two base models, both chat models of 7B and 13B size.
- Only the single-document conflict setting (at most one answer-bearing document) is studied.
Experimental setup
Datasets: SQuAD 2.0 RGB KNOT CMB
Benchmarks: SQuAD 2.0-Eval RGB KNOT CMB
Metrics: R_Ad adherence ratio R_Ro robustness ratio prior-probability adherence analysis conflicting answer match rate
Baselines: Base Prompt CoT COT-VE KAFT CAD CFP
Builds on: Direct Preference Optimization KAFT Chain-of-Thought prompting Context-Aware Decoding
Closest papers by meaning
- DynamicRAG: Leveraging Outputs of Large Language Model as Feedback for Dynamic Reranking in Retrieval-Augmented Generation (NeurIPS 2025 · similarity 0.87)
- Adapting to Non-Stationary Environments: Multi-Armed Bandit Enhanced Retrieval-Augmented Generation on Knowledge Graphs (AAAI 2025 · similarity 0.87)
- TPO: Aligning Large Language Models with Multi-branch & Multi-step Preference Trees (ICLR 2025 · similarity 0.87)
- A Systematic Exploration of Knowledge Graph Alignment with Large Language Models in Retrieval Augmented Generation (AAAI 2025 · similarity 0.87)
- Adaptive Chameleon or Stubborn Sloth: Revealing the Behavior of Large Language Models in Knowledge Conflicts (ICLR 2024 · similarity 0.87)
- Inference Scaling for Long-Context Retrieval Augmented Generation (ICLR 2025 · similarity 0.86)
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