ADWIN: Adaptive Windows for Horizon-Aware On-Policy Distillation

Kun Liang, Chenming Tang, Clive Bai, Weijie Liu, Saiyong Yang, Yunfang Wu


Abstract
On-policy distillation (OPD) transfers reasoning behavior by training a student on teacher feedback along student-generated trajectories, but standard full-rollout training ties every update to a costly completion and can over-allocate supervision to late positions with low marginal value for the current student. We revisit this assumption through the useful supervision horizon: student-induced rollouts can drift from teacher-preferred continuations, while aligned prefixes may already preserve the long-horizon OPD update direction. We propose ADWIN, an adaptive-window framework for OPD that treats rollout length as an online admissibility decision, training on short teacher-anchored prefixes while using delayed full-rollout probes to audit prefix–full alignment and adapt the next horizon with staleness control. Across math and code reasoning benchmarks in single-task, multi-task, and strong-to-weak settings, ADWIN improves the accuracy–compute trade-off over full-rollout OPD and prefix-based baselines, reducing end-to-end training cost by up to 4.1× while achieving comparable or better accuracy.
Anthology ID:
2026.emnlp-main.451
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
10371–10389
Language:
URL:
https://aclanthology.org/2026.emnlp-main.451/
DOI:
Bibkey:
Cite (ACL):
Kun Liang, Chenming Tang, Clive Bai, Weijie Liu, Saiyong Yang, and Yunfang Wu. 2026. ADWIN: Adaptive Windows for Horizon-Aware On-Policy Distillation. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 10371–10389, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
ADWIN: Adaptive Windows for Horizon-Aware On-Policy Distillation (Liang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.451.pdf