Ruize Xu
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2026
How do World Models and Policies Compose in LLM Agents? A Joint Spectral and Behavioral Account
Ruize Xu | Xiao Yu | Yujin Tang | Chenming Shang | Nikhil Singh
Findings of the Association for Computational Linguistics: EMNLP 2026
Ruize Xu | Xiao Yu | Yujin Tang | Chenming Shang | Nikhil Singh
Findings of the Association for Computational Linguistics: EMNLP 2026
How do LLM agents come to both understand environments they act in and master tasks set within them? Through controlled experiments combining world-model training (next-state prediction) and policy training (reward maximization), we investigate this question. We dissect the resulting models through their additive parameter updates. Geometrically, we find effective world-model updates are low-rank and share an input-feature subspace with policy updates while writing to nearly orthogonal output directions, whether trained separately or sequentially. However, we find that, in projection interventions, the sequential update induces more robustness than separate policy RL when removing the world model’s leading input directions, suggesting that it has learned alternative input pathways. Behaviorally, we find the sequentially trained agent explores a wider range of states and actions. Based on this, we ask: does policy training preserve world knowledge as well as it could? We probe this with training-free merging built on the geometrically motivated input basis plus an online world-model loss during policy RL, and show both improve over the untreated baseline. Our findings suggest world knowledge and task-directed ability can be learned in geometrically complementary forms, and that future post-training pipelines should consider how best to engineer the interface between them.
DMV-Bench: Diagnosing Long-Horizon Multimodal Agents’ Visual Memory with Incidental Cue Injection
Yujin Tang | Chenming Shang | Ruize Xu | Nikhil Singh
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Yujin Tang | Chenming Shang | Ruize Xu | Nikhil Singh
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Agent benchmarks for measuring memory largely study textual cases, in which information is deliberately extracted from the environment, written down, and then later retrieved. In other words, they assess what agents elected to record, not what they happened to see. We introduce **DMV-Bench** (code: https://github.com/yyyujintang/DMV-Bench), the first **interactive benchmark for visual memory in multimodal agents**, to study this often-neglected property. DMV-Bench is built on (1) a controlled home-furnishing e-commerce environment, supported by a catalog of 1,000 product variants, and (2) a text-leakage contract which ensures that the primary discriminative signal of each task is solely in the pixels. In DMV-Bench, agents undergo chains of autonomous shopping sessions in which every visited product image carries a unique, pre-rendered *incidental cue* that the agent is later asked to recall. We show that conventional solutions struggle with this task. Inspired by dual-coding theory, we propose a memory architecture that uses parallel visual and verbal codes, which we call **DualMem**. On DMV-Bench, DualMem outperforms a caption-only baseline *and* three recent multimodal agent-memory systems across multi-session chain lengths on multiple models. These gains persist even adjusting for memory-bank size and encoding-position bias. Further experiments also reveal an asymmetric division of labor between the two codes; a weighted coding scheme is often strongest. We view this as a step towards memory systems that preserve a richer record of agents’ observations.
2025
ConFit v2: Improving Resume-Job Matching using Hypothetical Resume Embedding and Runner-Up Hard-Negative Mining
Xiao Yu | Ruize Xu | Chengyuan Xue | Jinzhong Zhang | Xu Ma | Zhou Yu
Findings of the Association for Computational Linguistics: ACL 2025
Xiao Yu | Ruize Xu | Chengyuan Xue | Jinzhong Zhang | Xu Ma | Zhou Yu
Findings of the Association for Computational Linguistics: ACL 2025
A reliable resume-job matching system helps a company recommend suitable candidates from a pool of resumes and helps a job seeker find relevant jobs from a list of job posts. However, since job seekers apply only to a few jobs, interaction labels in resume-job datasets are sparse. We introduce ConFit v2, an improvement over ConFit to tackle this sparsity problem. We propose two techniques to enhance the encoder’s contrastive training process: augmenting job data with hypothetical reference resume generated by a large language model; and creating high-quality hard negatives from unlabeled resume/job pairs using a novel hard-negative mining strategy. This method also simplifies the representation space of the encoder. We evaluate ConFit v2 on two real-world datasets and demonstrate that it outperforms ConFit and prior methods (including BM25 and OpenAI text-embedding-003), achieving an average absolute improvement of 13.8% in recall and 17.5% in nDCG across job-ranking and resume-ranking tasks.