Improving Diffusion Language Model Decoding through Joint Search in Generation Order and Token Space

Yangyi Shen, Tianjian Feng, Jiaqi Han, Wen Wang, Tianlang Chen, Chunhua Shen, Jure Leskovec, Stefano Ermon


Abstract
Diffusion Language Models (DLMs) offer order-agnostic generation that can explore many possible decoding trajectories. However, current decoding methods commit to a single trajectory, limiting exploration in trajectory space. We introduce Order-Token Search to explore this space through jointly searching over generation order and token values. Its core is a likelihood estimator that scores denoising actions, enabling stable pruning and efficient exploration of diverse trajectories. Across mathematical reasoning and coding benchmarks, Order-Token Search consistently outperforms baselines on GSM8K, MATH500, Countdown, and HumanEval (3.1%, 3.8%, 7.9%, and 6.8% absolute over backbone), reaching accuracy comparable to diffu-GRPO post-training. Our work establishes joint search as a key component for advancing decoding in DLMs.
Anthology ID:
2026.emnlp-main.24
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:
513–532
Language:
URL:
https://aclanthology.org/2026.emnlp-main.24/
DOI:
Bibkey:
Cite (ACL):
Yangyi Shen, Tianjian Feng, Jiaqi Han, Wen Wang, Tianlang Chen, Chunhua Shen, Jure Leskovec, and Stefano Ermon. 2026. Improving Diffusion Language Model Decoding through Joint Search in Generation Order and Token Space. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 513–532, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Improving Diffusion Language Model Decoding through Joint Search in Generation Order and Token Space (Shen et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.24.pdf