ReasonFlow: Flow Matching that Thinks Step by Step

Bing Yan, Ge Sun, Juan J. de Pablo, Stefano Martiniani, Kyunghyun Cho


Abstract
Flow matching has shown strong promise as a continuous generative framework, but its standard formulation is not well-suited to reasoning problems. Conventional flow matching trains a model to transport noise directly toward a single final target. For tasks that require multi-step reasoning, this direct path is often too difficult: the final answer may be reachable only through a sequence of intermediate computations or transformations. Inspired by how autoregressive language models address this challenge through chain-of-thought supervision, we introduce ReasonFlow, a framework that brings the same scaffolding principle to flow matching. Instead of supervising the flow with only a final target, ReasonFlow constructs a sequence of CoT-induced anchor points derived from intermediate reasoning prefixes. During training, the clean target moves along a piecewise-linear path through these anchors before endpoint answer readout. This turns reasoning supervision from an output sequence into a trajectory-shaping signal for flow matching. Across arithmetic, chemistry, and logical-reasoning tasks, ReasonFlow substantially improves over no-CoT flow-matching baselines.
Anthology ID:
2026.findings-emnlp.2268
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:
48554–48571
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2268/
DOI:
Bibkey:
Cite (ACL):
Bing Yan, Ge Sun, Juan J. de Pablo, Stefano Martiniani, and Kyunghyun Cho. 2026. ReasonFlow: Flow Matching that Thinks Step by Step. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 48554–48571, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
ReasonFlow: Flow Matching that Thinks Step by Step (Yan et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.2268.pdf