Inference-Time Feedback for Reasoning Controllability in Diffusion Language Models

Clovis Barbour, Huixin Zhan


Abstract
Scientific NLP systems often require outputs that satisfy strict, machine-checkable constraints. In this work, we study structured-generation controllability along three axes: structural control, iterative correction, and decoding dynamics. Diffusion decoding is of particular interest because its iterative refinement may improve global structure and revision behavior, but may also introduce distinct failure modes such as termination instability and repetition. To quantify controllability, we evaluate compliance with five machine-checkable constraints: (i) required headings and (ii) correct ordering, which reflect global structural control; (iii) explicit end markers and (iv) per-section bullet constraints, which probe local constraint adherence; and (v) repetition avoidance, which captures generation stability under different decoding dynamics. We use these metrics to assess both single-pass generation and changes under iterative correction. Our goal is to isolate structural reliability under parser-facing requirements rather than to directly measure scientific correctness. Across our benchmark, diffusion models tend to better preserve global structure, while iterative improvement substantially improves explicit termination and other local control constraints. Hybrid systems show mixed behavior depending on decoding order. These results suggest that machine-checkable controllability can be usefully decomposed into global structure versus local control, and that the two may benefit from different inference-time strategies.
Anthology ID:
2026.acl-srw.61
Volume:
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (ACL 2026)
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Santosh T.Y.S.S., Juan Diego Rodriguez, Ona de Gibert
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
675–682
Language:
URL:
https://preview.aclanthology.org/ingest-acl/2026.acl-srw.61/
DOI:
Bibkey:
Cite (ACL):
Clovis Barbour and Huixin Zhan. 2026. Inference-Time Feedback for Reasoning Controllability in Diffusion Language Models. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (ACL 2026), pages 675–682, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
Inference-Time Feedback for Reasoning Controllability in Diffusion Language Models (Barbour & Zhan, ACL 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl/2026.acl-srw.61.pdf