DIAG: Diagnostic Iterative Alignment and Generation for Data-Efficient Mathematical Preference Distillation

Guhan Chen, Songtao Tian, Bohan Li, Hejin Wang, Ye-Xin Xie, Zixiong Yu


Abstract
Iterative preference optimization is essential for aligning Large Language Models on mathematical reasoning tasks, yet its efficiency is often throttled by signal scarcity: as the model improves, static problem sets become increasingly mismatched to the model’s evolving competence, producing rollouts that are either too easy or too hard and therefore non-informative, which leads to a scarcity of valid preference pairs. We propose DIAG, a Diagnostic Iterative Alignment and Generation framework that adaptively reshapes the practice distribution to increase informative supervision and focus training near the student’s current competence boundary. DIAG consists of two phases: (1) diagnosing valid preference-pair yield to calibrate the exploration-exploitation trade-off and allocate topic quotas via an Empirical Bayes shrinkage estimator, thereby prioritizing high-yield concepts; and (2) generating targeted practice, where a teacher synthesizes variants from the student’s failure traces. We further provide a theoretical view interpreting DIAG as a teacher-mediated approximation to KL-regularized reweighting of the practice distribution toward the student’s competence boundary, where valid preference-pair yield is maximized. Experiments show that DIAG boosts yield across iterations and delivers stronger reasoning performance under an iso-effective training budget, demonstrating that it can distill more informative preference supervision for mathematical reasoning.
Anthology ID:
2026.findings-emnlp.1104
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:
23345–23364
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1104/
DOI:
Bibkey:
Cite (ACL):
Guhan Chen, Songtao Tian, Bohan Li, Hejin Wang, Ye-Xin Xie, and Zixiong Yu. 2026. DIAG: Diagnostic Iterative Alignment and Generation for Data-Efficient Mathematical Preference Distillation. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 23345–23364, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
DIAG: Diagnostic Iterative Alignment and Generation for Data-Efficient Mathematical Preference Distillation (Chen et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.1104.pdf