Calibration-Free Early Stopping for Chain-of-Thought Reasoning via E-processes

Dong-Jae Lee, Gyojin Han, Junmo Kim


Abstract
Reasoning large language models (LLMs) benefit from test-time scaling, motivating adaptive policies that spend tokens when they help and stop early otherwise. Existing rules halt when a confidence or stability signal crosses a threshold, but such thresholds rarely transfer across models and datasets, and validation-calibrated rules lose their guarantee under shifts in test-time horizon or signal dynamics. We reframe adaptive stopping as sequential evidence accumulation along the reasoning trajectory rather than threshold calibration on held-out data. Our framework runs two e-processes on a shared per-chunk signal: a commit stream tracks the signal’s position relative to its slow trend, and an abstain stream tracks its signed velocity, making the two anti-correlated by construction. Under signal-level nulls on the per-chunk increments, Ville’s inequality yields an anytime-valid signal-level false-alarm bound at user-specified significance levels, with no held-out calibration. Across various model–dataset combinations, the framework matches or exceeds calibration-based stopping on the token–accuracy Pareto front using zero calibration data, and the same significance level transfers unchanged across cells where calibration becomes infeasible.
Anthology ID:
2026.findings-emnlp.1677
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
35798–35814
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1677/
DOI:
Bibkey:
Cite (ACL):
Dong-Jae Lee, Gyojin Han, and Junmo Kim. 2026. Calibration-Free Early Stopping for Chain-of-Thought Reasoning via E-processes. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 35798–35814, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Calibration-Free Early Stopping for Chain-of-Thought Reasoning via E-processes (Lee et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1677.pdf