Kai Han
Other people with similar names: Kai Han, Kai Han
2026
CodeBind: Decoupled Representation Learning for Multimodal Alignment with Unified Compositional Codebook
Zeyu Chen | Jie Li | Kai Han
Findings of the Association for Computational Linguistics: ACL 2026
Zeyu Chen | Jie Li | Kai Han
Findings of the Association for Computational Linguistics: ACL 2026
Multimodal representation alignment is pivotal for large language models and robotics. Traditional methods are often hindered by cross-modal information discrepancies and data scarcity, leading to suboptimal alignment spaces that overlook modality-unique features. We propose CodeBind, a framework that optimizes multimodal representation spaces through a modality-shared-specific codebook design. By incrementally aligning target and bridging modalities, CodeBind bypasses the need for fully paired data. Unlike traditional hard alignment, CodeBind decomposes features into shared components for semantic consistency and specific components for modality-unique details. This design utilizes a compositional vector quantization scheme, where a shared codebook bridges modality gaps and modality-specific codebooks mitigate representation bias by preventing dominant modalities from overshadowing others. Validated across nine modalities (text, image, video, audio, depth, thermal, tactile, 3D point cloud, EEG), CodeBind achieves state-of-the-art performance in multimodal classification and retrieval tasks. Project page: https://visual-ai.github.io/codebind
Ascending the Infinite Ladder: Benchmarking Spatial Deformation Reasoning in Vision-Language Models
Jiahuan Zhang | Shunwen Bai | Tianheng Wang | KaiWen Guo | Zijia Song | Hanqing WU | Guozheng Rao | Kai Han | Kaicheng Yu
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Jiahuan Zhang | Shunwen Bai | Tianheng Wang | KaiWen Guo | Zijia Song | Hanqing WU | Guozheng Rao | Kai Han | Kaicheng Yu
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Humans naturally possess the spatial reasoning ability to form and manipulate images and structures of objects in space. There is an increasing effort to endow Vision-Language Models (VLMs) with similar spatial reasoning capabilities. However, it remains unclear whether these models truly understand and manipulate spatial objects or not. To address this question, we propose a new evaluation framework aimed at assessing the performance of VLMs in spatial deformation reasoning tasks. Specifically, we construct a benchmark for spatial deformation reasoning from 2D to 3D. We explore whether the model can effectively perform spatial deformation reasoning from two directions: forward reasoning (given the operations, find the final state) and reverse reasoning (given the final state, determine the operations). We adopt a ladder competition format, using the number of deformation steps as the level classification criterion, with the goal of exploring the boundaries of the model’s deformation reasoning capabilities. Interestingly, the benchmarking results reveal that almost no model demonstrates plausible spatial deformation reasoning abilities. Furthermore, even after applying targeted training and mainstream reasoning enhancement methods, the models are still unable to perform well on 3D spatial deformation reasoning.
2025
PruneVid: Visual Token Pruning for Efficient Video Large Language Models
Xiaohu Huang | Hao Zhou | Kai Han
Findings of the Association for Computational Linguistics: ACL 2025
Xiaohu Huang | Hao Zhou | Kai Han
Findings of the Association for Computational Linguistics: ACL 2025
We introduce PruneVid, a training-free visual token pruning method designed to enhance the efficiency of multimodal video understanding. While Large Language Models (LLMs) have shown promising performance on video tasks due to their advanced visual comprehension capabilities, the substantial redundancy inherent in video data poses significant computational challenges. To address this issue, PruneVid (1) reduces intrinsic video redundancy by merging temporally static and spatially similar tokens, and (2) leverages LLMs’ inherent ability to selectively prune visual tokens irrelevant to specific queries, thereby improving model efficiency. We validate our method across multiple video benchmarks, demonstrating that PruneVid can prune over 80% of tokens while maintaining competitive performance when combined with different video LLMs. Our results highlight PruneVid’s superior effectiveness and efficiency compared to existing pruning methods.
GAMEBoT: Transparent Assessment of LLM Reasoning in Games
Wenye Lin | Jonathan Roberts | Yunhan Yang | Samuel Albanie | Zongqing Lu | Kai Han
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Wenye Lin | Jonathan Roberts | Yunhan Yang | Samuel Albanie | Zongqing Lu | Kai Han
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Large Language Models (LLMs) are increasingly deployed in real-world applications that demand complex reasoning. To track progress, robust benchmarks are required to evaluate their capabilities beyond superficial pattern recognition. However, current LLM reasoning benchmarks often face challenges such as insufficient interpretability, performance saturation or data contamination. To address these challenges, we introduce GAMEBoT, a gaming arena designed for rigorous and transparent assessment of LLM reasoning capabilities. GAMEBoT decompose complex reasoning in games into predefined modular subproblems. This decomposition allows us to design a suite of Chain-of-Thought (CoT) prompts infused with domain knowledge to guide LLMs in addressing these subproblems before action selection. Furthermore, we develop a suite of rule-based algorithms to generate ground truth for these subproblems, enabling rigorous validation of the LLMs’ intermediate reasoning steps. This approach facilitates evaluation of both the quality of final actions and the accuracy of the underlying reasoning process. GAMEBoT also naturally alleviates the risk of data contamination through dynamic games and head-to-head LLM competitions. We benchmark 17 prominent LLMs across eight games, encompassing various strategic abilities and game characteristics. Our results suggest that GAMEBoT presents a significant challenge, even when LLMs are provided with detailed CoT prompts.