Tej Deep Pala


2025

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Emma-X: An Embodied Multimodal Action Model with Grounded Chain of Thought and Look-ahead Spatial Reasoning
Qi Sun | Pengfei Hong | Tej Deep Pala | Vernon Toh | U-Xuan Tan | Deepanway Ghosal | Soujanya Poria
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)

Traditional reinforcement learning-based robotic control methods are often task-specific and fail to generalize across diverse environments or unseen objects and instructions. Visual Language Models (VLMs) demonstrate strong scene understanding and planning capabilities but lack the ability to generate actionable policies tailored to specific robotic embodiments. To address this, Visual-Language-Action (VLA) models have emerged, yet they face challenges in long-horizon spatial reasoning and grounded task planning. In this work, we propose the Embodied Multimodal Action Model with Grounded Chain of Thought and Look-ahead Spatial Reasoning, EMMA-X. EMMA-X leverages our constructed hierarchical embodiment dataset based on BridgeV2, containing 60,000 robot manipulation trajectories auto-annotated with grounded task reasoning and spatial guidance. Additionally, we introduce a trajectory segmentation strategy based on gripper states and motion trajectories, which can help mitigate hallucination in grounding subtask reasoning generation. Experimental results demonstrate that EMMA-X achieves superior performance over competitive baselines, particularly in real-world robotic tasks requiring spatial reasoning.

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Ferret: Faster and Effective Automated Red Teaming with Reward-Based Scoring Technique
Tej Deep Pala | Vernon Toh | Rishabh Bhardwaj | Soujanya Poria
Findings of the Association for Computational Linguistics: EMNLP 2025

As large language models (LLMs) are increasingly integrated into real-world applications, ensuring their safety and robustness is critical. Automated red-teaming methods generate adversarial attacks to identify vulnerabilities, but existing approaches often face challenges like slow performance, limited categorical diversity, and high resource demands. We propose Ferret, a novel method that enhances the baseline, Rainbow Teaming by generating multiple adversarial prompt mutations per iteration and ranking them using scoring functions such as reward models, Llama Guard, and LLM-as-a-judge. Ferret achieves a 95% attack success rate (ASR), a 46% improvement over baseline, and reduces time to a 90% ASR by 15.2%. Additionally, it generates transferable adversarial prompts effective on larger LLMs. Our code is available at https://github.com/declare-lab/ferret

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Error Typing for Smarter Rewards: Improving Process Reward Models with Error-Aware Hierarchical Supervision
Tej Deep Pala | Panshul Sharma | Amir Zadeh | Chuan Li | Soujanya Poria
Findings of the Association for Computational Linguistics: EMNLP 2025

Large Language Models (LLMs) are prone to hallucination, especially during multi‐hop and reasoning-intensive tasks such as mathematical problem solving. While Outcome Reward Models verify only final answers, Process Reward Models (PRMs) score each intermediate step to steer generation toward coherent solutions. We introduce PathFinder‐PRM, a novel hierarchical, error‐aware discriminative PRM that first classifies math and consistency errors at each step, then combines these fine‐grained signals to estimate step correctness. To train PathFinder‐PRM, we construct a 400K‐sample dataset by enriching the human‐annotated PRM800K corpus and RLHFlow Mistral traces with three‐dimensional step‐level labels. On PRMBench, PathFinder‐PRM achieves a new state‐of‐the‐art PRMScore of 67.7, outperforming the prior best (65.5) while using 3× less data. When applied to reward guided greedy search, our model yields prm@8 48.3, a +1.5 point gain over the strongest baseline. These results demonstrate that decoupled error detection and reward estimation not only boost fine‐grained error detection but also substantially improve end‐to‐end, reward‐guided mathematical reasoning with greater data efficiency. Our code is available at https://github.com/declare-lab/PathFinder-PRM.