CSPO: Alleviating Reward Ambiguity for Structured Table-to-LaTeX Generation

Yunfan Yang, Cuiling Lan, Jitao Sang, Yan Lu


Abstract
Tables contain rich structured information, yet when stored as images their contents remain "locked" within pixels. Converting table images into LaTeX code enables faithful digitization and reuse, but current multimodal large language models (MLLMs) often fail to preserve structural, style, or content fidelity. Conventional post-training with reinforcement learning (RL) typically relies on a single aggregated reward, leading to reward ambiguity that conflates multiple behavioral aspects and hinders effective optimization. We propose Component-Specific Policy Optimization (CSPO), an RL framework that disentangles optimization across LaTeX tables components—structure, style, and content. In particular, CSPO assigns component-specific rewards and backpropagates each signal only through the tokens relevant to its component, alleviating reward ambiguity and enabling targeted component-wise optimization. To comprehensively assess performance, we introduce a set of hierarchical evaluation metrics. Extensive experiments demonstrate the effectiveness of CSPO, underscoring the importance of component-specific optimization for reliable structured generation.
Anthology ID:
2026.acl-long.1163
Volume:
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
ACL
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Publisher:
Association for Computational Linguistics
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Pages:
25374–25391
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URL:
https://preview.aclanthology.org/ingest-acl/2026.acl-long.1163/
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Cite (ACL):
Yunfan Yang, Cuiling Lan, Jitao Sang, and Yan Lu. 2026. CSPO: Alleviating Reward Ambiguity for Structured Table-to-LaTeX Generation. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 25374–25391, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
CSPO: Alleviating Reward Ambiguity for Structured Table-to-LaTeX Generation (Yang et al., ACL 2026)
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https://preview.aclanthology.org/ingest-acl/2026.acl-long.1163.pdf
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