Pause and Reflect: Conformal Aggregation for Chain-of-Thought Reasoning

Fuente: arXiv
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Main Authors: Gu, Yu, Yu, Zijun, Nia, Vahid Partovi, Asgharian, Masoud
Format: Preprint
Published: 2026
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author Gu, Yu
Yu, Zijun
Nia, Vahid Partovi
Asgharian, Masoud
author_facet Gu, Yu
Yu, Zijun
Nia, Vahid Partovi
Asgharian, Masoud
contents Chain-of-thought (CoT) reasoning with self-consistency improves performance by aggregating multiple sampled reasoning paths. In this setting, correctness is no longer tied to a single reasoning trace but to the aggregation rule over a pool of candidate paths, making aggregation uncertainty the central challenge. This issue is critical where confidently incorrect answers are far more costly than abstentions. We introduce a conformal procedure for CoT reasoning that directly addresses aggregation uncertainty. Our approach replaces majority voting with weighted score aggregation over reasoning paths and calibrates an abstention rule using conformal risk control. This approach leads to finite-sample guarantees on the confident-error rate--the probability that the system answers and is wrong. We further identify score separability as the key condition under which abstention provably improves selective accuracy, and derive closed-form expressions that predict accuracy gains from calibration data alone. The method is fully inference-time, and requires no retraining. Across four benchmarks, four open-source models, and three score classes, realized confident-error rates are consistent with the prescribed targets up to calibration-split and test-set variability. Our method achieves $90.1\%$ selective accuracy on GSM8K by abstaining on less than $5\%$ of problems, compared with $82\%$ accuracy under majority-voting baseline.
format Preprint
id arxiv_https___arxiv_org_abs_2605_14098
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Pause and Reflect: Conformal Aggregation for Chain-of-Thought Reasoning
Gu, Yu
Yu, Zijun
Nia, Vahid Partovi
Asgharian, Masoud
Machine Learning
Computation and Language
Chain-of-thought (CoT) reasoning with self-consistency improves performance by aggregating multiple sampled reasoning paths. In this setting, correctness is no longer tied to a single reasoning trace but to the aggregation rule over a pool of candidate paths, making aggregation uncertainty the central challenge. This issue is critical where confidently incorrect answers are far more costly than abstentions. We introduce a conformal procedure for CoT reasoning that directly addresses aggregation uncertainty. Our approach replaces majority voting with weighted score aggregation over reasoning paths and calibrates an abstention rule using conformal risk control. This approach leads to finite-sample guarantees on the confident-error rate--the probability that the system answers and is wrong. We further identify score separability as the key condition under which abstention provably improves selective accuracy, and derive closed-form expressions that predict accuracy gains from calibration data alone. The method is fully inference-time, and requires no retraining. Across four benchmarks, four open-source models, and three score classes, realized confident-error rates are consistent with the prescribed targets up to calibration-split and test-set variability. Our method achieves $90.1\%$ selective accuracy on GSM8K by abstaining on less than $5\%$ of problems, compared with $82\%$ accuracy under majority-voting baseline.
title Pause and Reflect: Conformal Aggregation for Chain-of-Thought Reasoning
topic Machine Learning
Computation and Language
url https://arxiv.org/abs/2605.14098