titleLearning Where Outcomes Change:Credit-Addressable Reasoning for Multimodal Geometry
authorsJiani Guo, Junjie Wang, Jie Wu, Pengxiang Zhao, Dongdong Zhang, Shaohan Huang, Yujiu Yang, Furu Wei
date2026-08-31
venuearXiv (preprint, not peer reviewed)
idarXiv:2608.30457
affiliationTsinghua IIGroup
upvotes4 (Hugging Face Daily Papers, 2026-11-01)
linksabs pdf hf
abstractMultimodal geometry reasoning requires VLMs to extract precise visual relations and preserve them through multi-step deduction. Existing free-form traces obscure the decisions that determine the answer, and trajectory-level reinforcement learning distributes a single terminal signal across the entire response. We introduce credit-addressable reasoning, in which the semantic units exposed during inference also define where learning compares alternatives and assigns credit. We instantiate this principle with Code-CoT, which retains the diagram, represents visual relations as line-addressable executable code, and organizes reasoning into typed events, and CE-GRPO, which selects event boundaries using structural priors and type-normalized entropy, samples complete continuations from shared prefixes, and converts outcome differences into localized advantages. Across nine geometry benchmarks, CE-GRPO achieves an average accuracy of 76.04, outperforming Qwen3-VL-8B and trajectory-level GRPO by 8.09 and 3.43 points, respectively. Its relative advantage increases with the number of intermediate events, demonstrating the value of representation--optimization co-design for long, dependency-heavy multimodal reasoning.

cite

@misc{guo2026learning,
  title={Learning Where Outcomes Change:Credit-Addressable Reasoning for Multimodal Geometry},
  author={Jiani Guo and Junjie Wang and Jie Wu and Pengxiang Zhao and Dongdong Zhang and Shaohan Huang and Yujiu Yang and Furu Wei},
  year={2026},
  eprint={2608.30457},
  archivePrefix={arXiv},
  url={https://arxiv.org/abs/2608.30457}
}