Anchored Reasoning on Tables: Bridging the Verifiability Gap in Multimodal Reinforcement Learning

Yubo Jiang, Yitong An, Fengying Xie, Zhiguo Jiang, Haopeng Zhang


Abstract
The Verifiability Gap in table reasoning arises when multimodal LLMs produce correct answers while grounding intermediate steps in unsupported visual evidence. Intermediate visual claims are often not exposed in a symbolically addressable form, making standard RL with verifiable rewards unable to reliably inspect whether a reasoning step is actually supported by the image. We mitigate this gap for table reasoning with Anchored Reasoning, which turns each reasoning step into a checkable (coordinate, value, structural role) claim over the table grid. We instantiate this paradigm as V-tableR1: a policy VLM generates anchor-laden visual chains-of-thought, while a learned critic VLM estimates anchor fidelity against the source image. The policy is trained with PGPO, a GRPO-based process-guided formulation that integrates critic-gated trajectory rewards with stabilization mechanisms for long anchor-laden rollouts. V-tableR1 (4B) achieves the best open-source average accuracy across seven tabular reasoning benchmarks, obtains state-of-the-art results on several individual datasets, surpasses open-source models up to 18× its size in aggregate, and improves over its SFT baseline by up to 10.66% absolute accuracy.
Anthology ID:
2026.findings-emnlp.2306
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:
49477–49497
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2306/
DOI:
Bibkey:
Cite (ACL):
Yubo Jiang, Yitong An, Fengying Xie, Zhiguo Jiang, and Haopeng Zhang. 2026. Anchored Reasoning on Tables: Bridging the Verifiability Gap in Multimodal Reinforcement Learning. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 49477–49497, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Anchored Reasoning on Tables: Bridging the Verifiability Gap in Multimodal Reinforcement Learning (Jiang et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.2306.pdf