通过融合证据学习与谱感知对比学习,提升动态图中异常数据的检测能力。
Evidential Spectrum-Aware Contrastive Learning for OOD Detection in Dynamic Graphs
- 用证据深度学习重新定义输出为狄利克雷分布,捕捉输入不确定性。
- 设计谱感知增强模块生成近似异常样本,扩大正常与异常得分差距。
- 适用于安全敏感场景下的动态图异常检测,尤其适合无异常训练数据时。
动态图中的分布外(OOD)检测旨在识别新流入数据是否偏离已知正常数据分布,近年在安全敏感领域受到关注。现有方法多针对静态图,面临两大挑战:一、单点估计导致高偏差与高方差,使预测对数据随机性敏感;二、缺乏异常训练数据导致得分同质化,模型仅学习正常模式,造成异常得分普遍偏低且正常与异常得分差距过小。为此,本文从证据深度学习(EDL)视角出发,提出EviSEC——一种基于谱感知对比学习的新型OOD检测器。设计证据神经网络,将输出重定义为后验狄利克雷分布,以分布不确定性解释输入随机性,弥补单点估计的不足。同时引入谱感知增强模块,生成近似异常样本,识别高异常得分模式,有效拓宽正常与异常得分差距,缓解得分同质化问题。在多个真实世界数据集上的大量实验表明,EviSEC能有效检测动态图中的异常样本。
原文摘要 · Abstract (English)
Recently, Out-of-distribution (OOD) detection in dynamic graphs, which aims to identify whether incoming data deviates from the distribution of the in-distribution (ID) training set, has garnered considerable attention in security-sensitive fields. Current OOD detection paradigms primarily focus on static graphs and confront two critical challenges: i) high bias and high variance caused by single-point estimation, which makes the predictions sensitive to randomness in the data; ii) score homogenization resulting from the lack of OOD training data, where the model only learns ID-specific patterns, resulting in overall low OOD scores and a narrow score gap between ID and OOD data. To tackle these issues, we first investigate OOD detection in dynamic graphs through the lens of Evidential Deep Learning (EDL). Specifically, we propose EviSEC, an innovative and effective OOD detector via Evidential Spectrum-awarE Contrastive Learning. We design an evidential neural network to redefine the output as the posterior Dirichlet distribution, explaining the randomness of inputs through the uncertainty of distribution, which is overlooked by single-point estimation. Moreover, spectrum-aware augmentation module generates OOD approximations to identify patterns with high OOD scores, thereby widening the score gap between ID and OOD data and mitigating score homogenization. Extensive experiments on real-world datasets demonstrate that EviSAC effectively detects OOD samples in dynamic graphs.
Thank you to arXiv for use of its open access interoperability. PaperDance 不是 arXiv 官方产品;中文卡片由大模型生成,请以原文为准。