Jiacheng Wang
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2026
Patch the Distribution Mismatch: RL-Based Data Rewriting for Stable Downstream SFT
Jiacheng Wang | Zhijie Liu | Ping Jian | Zirong Chen | Ke Ren Liao | Zhen Yang | Zhongbin Guo
Findings of the Association for Computational Linguistics: EMNLP 2026
Jiacheng Wang | Zhijie Liu | Ping Jian | Zirong Chen | Ke Ren Liao | Zhen Yang | Zhongbin Guo
Findings of the Association for Computational Linguistics: EMNLP 2026
Large language models are commonly adapted to downstream tasks through supervised fine-tuning (SFT), but substantial distribution mismatch between downstream supervision and a model’s generation distribution can intensify catastrophic forgetting. Data rewriting offers a data-centric way to narrow this mismatch before SFT. Existing methods, however, typically sample rewrites from a prompt-induced conditional distribution, which need not align with the backbone’s natural question-answering generation distribution, and fixed templates can reduce output diversity. We formulate data rewriting as a policy-learning problem and train a lightweight LoRA rewriting policy with reinforcement learning. The policy optimizes question-answering-style distributional alignment and semantic diversity under a hard task-consistency gate, producing verified supervision for downstream SFT. Across three instruction-tuned backbones, the resulting models attain downstream gains broadly comparable to standard SFT while reducing degradation on non-downstream benchmarks in every evaluated setting. Additional experiments on logical reasoning and medical question answering provide preliminary evidence that a rewriting policy can be reused across domains for the same backbone.
HINTBench: Horizon-agent Intrinsic Non-attack Trajectory Benchmark
Jiacheng Wang | Jinchang Hou | Fabian Wang | Ping Jian | Zhonghou Lv | Chenfu Bao
Findings of the Association for Computational Linguistics: EMNLP 2026
Jiacheng Wang | Jinchang Hou | Fabian Wang | Ping Jian | Zhonghou Lv | Chenfu Bao
Findings of the Association for Computational Linguistics: EMNLP 2026
Existing agent-safety evaluation has focused mainly on externally induced risks. Yet agents may still enter unsafe trajectories under benign conditions. We study this complementary but underexplored setting through the lens of intrinsic risk, where intrinsic failures remain latent, propagate across long-horizon execution, and eventually lead to high-consequence outcomes. To evaluate this setting, we introduce non-attack intrinsic risk auditing, a guard-oriented safety evaluation task, and present HINTBench, a benchmark of 596 agent trajectories, comprising 400 synthetic risky trajectories, 136 synthetic safe trajectories, 30 reconstructed real-world risky trajectories, and 30 reconstructed real-world safe trajectories, with an average length of 24.0 steps. HINTBench supports three tasks: risk detection, risk-step localization, and intrinsic failure-type identification, with annotations organized under a unified five-constraint taxonomy. Experiments reveal a substantial capability gap: strong LLMs perform well on trajectory-level risk detection, but the best model remains below 37 on fine-grained Strict-F1 for risk-step localization. Existing off-the-shelf guard models evaluated under their native prompts transfer poorly to this setting. These findings establish intrinsic risk auditing as an open challenge for agent safety.
Can LLMs See Without Pixels? Benchmarking Spatial Intelligence from Textual Descriptions
Zhongbin Guo | Zhen Yang | Yushan Li | Xinyue Zhang | Wenyu Gao | Jiacheng Wang | Chengzhi Li | Xiangrui Liu | Ping Jian
Findings of the Association for Computational Linguistics: ACL 2026
Zhongbin Guo | Zhen Yang | Yushan Li | Xinyue Zhang | Wenyu Gao | Jiacheng Wang | Chengzhi Li | Xiangrui Liu | Ping Jian
Findings of the Association for Computational Linguistics: ACL 2026
Recent advancements in Spatial Intelligence (SI) have predominantly relied on Vision-Language Models (VLMs), yet a critical question remains: does spatial understanding originate from visual encoders or the fundamental reasoning backbone? Inspired by this question, we introduce SiT-Bench, a novel benchmark designed to evaluate the SI performance of Large Language Models (LLMs) without pixel-level input, comprises over 3,800 expert-annotated items across five primary categories and 17 subtasks, ranging from egocentric navigation and perspective transformation to fine-grained robotic manipulation. By converting single/multi-view scenes into high-fidelity, coordinate-aware textual descriptions, we challenge LLMs to perform symbolic textual reasoning rather than visual pattern matching. Evaluation results of state-of-the-art (SOTA) LLMs reveals that while models achieve proficiency in localized semantic tasks, a significant “spatial gap” remains in global consistency. Notably, we find that explicit spatial reasoning significantly boosts performance, suggesting that LLMs possess latent world-modeling potential. Our proposed dataset SiT-Bench serves as a foundational resource to foster the development of spatially-grounded LLM backbones for future VLMs and embodied agents.