Bochen Lin
Author directory2026
Node-to-Neighborhood Semantic Consistency: Text-Topology Alignment for TAGs Anomaly Detection
Bochen Lin | Jianxiang Yu | Jiayi Wu | Lin QI | Lu Huang | Xiang Li
Findings of the Association for Computational Linguistics: EMNLP 2026
Bochen Lin | Jianxiang Yu | Jiayi Wu | Lin QI | Lu Huang | Xiang Li
Findings of the Association for Computational Linguistics: EMNLP 2026
Graph anomaly detection (GAD) on text-attributed graphs (TAGs) is vital for applications such as fraud detection and academic integrity verification. Existing approaches generally fall into two paradigms. GNN-based methods capture structural patterns but struggle to capture fine-grained textual semantics. Methods integrating LLMs with graphs improve semantic understanding yet fail to fully comprehend topological relationships among neighbors. Moreover, both paradigms overlook the correspondence between textual semantics and graph topological relationships, limiting their ability to identify nodes whose semantics are inconsistent with their neighborhoods. In this paper, we formalize TAG anomaly detection as a node-to-neighborhood semantic consistency problem, where anomalies may arise from either textual semantic mismatch or topological deviation between a node and its neighbors. We propose N2NSC (Node-to-Neighborhood Semantic Consistency), a framework that captures the correspondence between graph topology and textual semantics through two complementary fusion paths. The two pathways work synergistically, enabling the LLM to jointly use textual and structural neighborhood information for anomaly detection. Extensive experiments across eight benchmark datasets, with additional validation on two real-world fraud datasets, demonstrate the effectiveness of N2NSC.
Negative Advantage Is a Double-Edged Sword: Calibrating advantages in GRPO for Search Agents
Jiayi Wu | Ruobing Xie | Zeqian Huang | Lei Jiang | Can Xu | Kangyang Luo | Bochen Lin | Ming Gao | Xiang Li
Findings of the Association for Computational Linguistics: EMNLP 2026
Jiayi Wu | Ruobing Xie | Zeqian Huang | Lei Jiang | Can Xu | Kangyang Luo | Bochen Lin | Ming Gao | Xiang Li
Findings of the Association for Computational Linguistics: EMNLP 2026
Search agents achieve strong question-answering performance through multi-turn interactions with search engines, with Group Relative Policy Optimization (GRPO) being a widely used training algorithm. However, GRPO-style algorithms still face several challenges in multi-hop search settings. First, correct intermediate steps are often penalized when the final answer is wrong. Second, training is highly unstable, often causing degradation of natural language ability or even catastrophic training collapse. Our analysis attributes these issues to coarse-grained advantage assignment and an imbalance between positive and negative advantages. To address these problems, we propose CalibAdv, an advantage calibration method specifically designed for search agents that enables more accurate and more stable modeling of penalties and rewards. Specifically, CalibAdv leverages the correctness of intermediate steps to downscale excessive negative advantages at a fine-grained level. It then further rebalances positive and negative advantages to improve training stability. Importantly, CalibAdv adopts a lightweight design that calibrates advantages from standard rollout signals, making it simple and easy to deploy. Extensive experiments across three models and seven benchmarks demonstrate that CalibAdv improves both model performance and training stability. Our code is available at https://github.com/wujwyi/CalibAdv.