Yitong An
Author directory2026
Anchored Reasoning on Tables: Bridging the Verifiability Gap in Multimodal Reinforcement Learning
Yubo Jiang | Yitong An | Fengying Xie | Zhiguo Jiang | Haopeng Zhang
Findings of the Association for Computational Linguistics: EMNLP 2026
Yubo Jiang | Yitong An | Fengying Xie | Zhiguo Jiang | Haopeng Zhang
Findings of the Association for Computational Linguistics: EMNLP 2026
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.