DreamReasoner-8B: Block-Size Curriculum Learning for Diffusion Reasoning Models

Zirui Wu, Lin Zheng, Jiacheng Ye, Shansan Gong, Xueliang Zhao, Yansong Feng, Wei Bi, Lingpeng Kong


Abstract
Block diffusion language models accelerate decoding through parallel block-wise denoising, yet whether they can be reliably scaled for long chain-of-thought (CoT) reasoning remains unresolved. To this end, we develop -8B, an open-source block diffusion reasoning model, and conduct a systematic study of how training and inference block sizes affect long-CoT reasoning. Our analysis reveals a stark performance disparity: training with large block sizes yields remarkably poor reasoning, whereas small block sizes preserve effective reasoning. To bridge this granularity gap, we propose block-size curriculum learning, which gradually transitions training from fine-grained to coarse-grained block sizes, thereby overcoming this limitation and enabling strong reasoning performance that generalizes across diverse inference block sizes. On mathematical and code reasoning benchmarks, -8B achieves results competitive with leading open autoregressive models such as Qwen3-8B. This work establishes a practical foundation for efficient, reasoning-capable diffusion language models. We release our model at https://github.com/DreamLM/DreamReasoner.
Anthology ID:
2026.emnlp-main.1508
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
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Pages:
34440–34453
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1508/
DOI:
Bibkey:
Cite (ACL):
Zirui Wu, Lin Zheng, Jiacheng Ye, Shansan Gong, Xueliang Zhao, Yansong Feng, Wei Bi, and Lingpeng Kong. 2026. DreamReasoner-8B: Block-Size Curriculum Learning for Diffusion Reasoning Models. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 34440–34453, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
DreamReasoner-8B: Block-Size Curriculum Learning for Diffusion Reasoning Models (Wu et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1508.pdf