Decomposed Prompting Does Not Fix Knowledge Gaps, But Helps Models Say "I Don't Know"

Fuente: arXiv
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Autori principali: Madhwal, Dhruv, Zhang, Lyuxin David, Roth, Dan, Wolfson, Tomer, Gupta, Vivek
Natura: Preprint
Pubblicazione: 2026
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author Madhwal, Dhruv
Zhang, Lyuxin David
Roth, Dan
Wolfson, Tomer
Gupta, Vivek
author_facet Madhwal, Dhruv
Zhang, Lyuxin David
Roth, Dan
Wolfson, Tomer
Gupta, Vivek
contents Large language models often struggle to recognize their knowledge limits in closed-book question answering, leading to confident hallucinations. While decomposed prompting is typically used to improve accuracy, we investigate its impact on reliability. We evaluate three task-equivalent prompting regimes: Direct, Assistive, and Incremental, across different model scales and multi-hop QA benchmarks. We find that although accuracy gains from decomposition diminish in frontier models, disagreements between prompting regimes remain highly indicative of potential errors. Because factual knowledge is stable while hallucinations are stochastic, cross-regime agreement provides a precise signal of internal uncertainty. We leverage this signal to implement a training-free abstention policy that requires no retrieval or fine-tuning. Our results show that disagreement-based abstention outperforms standard uncertainty baselines as an error detector, improving both F1 and AUROC across settings. This demonstrates that decomposition-based prompting can serve as a practical diagnostic probe for model reliability in closed-book QA.
format Preprint
id arxiv_https___arxiv_org_abs_2602_04853
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Decomposed Prompting Does Not Fix Knowledge Gaps, But Helps Models Say "I Don't Know"
Madhwal, Dhruv
Zhang, Lyuxin David
Roth, Dan
Wolfson, Tomer
Gupta, Vivek
Computation and Language
Large language models often struggle to recognize their knowledge limits in closed-book question answering, leading to confident hallucinations. While decomposed prompting is typically used to improve accuracy, we investigate its impact on reliability. We evaluate three task-equivalent prompting regimes: Direct, Assistive, and Incremental, across different model scales and multi-hop QA benchmarks. We find that although accuracy gains from decomposition diminish in frontier models, disagreements between prompting regimes remain highly indicative of potential errors. Because factual knowledge is stable while hallucinations are stochastic, cross-regime agreement provides a precise signal of internal uncertainty. We leverage this signal to implement a training-free abstention policy that requires no retrieval or fine-tuning. Our results show that disagreement-based abstention outperforms standard uncertainty baselines as an error detector, improving both F1 and AUROC across settings. This demonstrates that decomposition-based prompting can serve as a practical diagnostic probe for model reliability in closed-book QA.
title Decomposed Prompting Does Not Fix Knowledge Gaps, But Helps Models Say "I Don't Know"
topic Computation and Language
url https://arxiv.org/abs/2602.04853