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arXiv 2511.06529cs.LGcs.AI

TriShGAN:增强多元时间序列反事实解释中的稀疏性与鲁棒性

TriShGAN: Enhancing Sparsity and Robustness in Multivariate Time Series Counterfactuals Explanation

Hongnan Ma, Yiwei Shi, Guanxiong Sun, Mengyue Yang, Weiru Liu

AI总结:

本文提出TriShGAN,通过在CounteRGAN框架中引入三元组损失和Shapelet提取器,在保持低代价的同时增强多元时间序列反事实解释的鲁棒性与稀疏性。

摘要:

在决策过程中,利益相关者通常依赖反事实解释,这种解释提供关于应如何改变被查询实例以改变AI系统结果的建议。然而,为多元时间序列生成这些解释面临挑战,因为其具有复杂的多维特性。传统的基于“最近不同邻”(Nearest Unlike Neighbor,NUN)的方法通常用来自NUN的有影响力的子序列替换被查询时间序列中的子序列,但由于刚性直接替换,这在现实场景中并不总是可行的。基于残差生成对抗网络的反事实方法旨在通过从观测数据的分布中学习来生成合成的反事实解释,以解决这一问题。然而,这些方法主要侧重于最小化从被查询时间序列到反事实解释的代价,往往忽视了使反事实解释远离决策边界的重要性。这种疏忽可能导致:如果模型内部发生微小变化,所生成的解释就不再符合反事实的条件。为了生成更鲁棒的反事实解释,我们提出了TriShGAN,它在CounteRGAN框架的基础上通过引入三元组损失(triplet loss)进行了增强。这种无监督学习方法利用距离度量学习,促使反事实解释不仅保持与被查询时间序列接近,还能捕获具有期望结果的实例的特征分布,从而在最小代价与鲁棒性之间实现更好的平衡。此外,我们集成了一个Shapelet提取器,该提取器策略性地选择高维被查询时间序列中最具判别力的部分,以增强反事实解释的稀疏性并提高训练过程的效率。

英文摘要:

In decision-making processes, stakeholders often rely on counterfactual explanations, which provide suggestions about what should be changed in the queried instance to alter the outcome of an AI system. However, generating these explanations for multivariate time series presents challenges due to their complex, multi-dimensional nature. Traditional Nearest Unlike Neighbor-based methods typically substitute subsequences in a queried time series with influential subsequences from an NUN, which is not always realistic in real-world scenarios due to the rigid direct substitution. Counterfactual with Residual Generative Adversarial Networks-based methods aim to address this by learning from the distribution of observed data to generate synthetic counterfactual explanations. However, these methods primarily focus on minimizing the cost from the queried time series to the counterfactual explanations and often neglect the importance of distancing the counterfactual explanation from the decision boundary. This oversight can result in explanations that no longer qualify as counterfactual if minor changes occur within the model. To generate a more robust counterfactual explanation, we introduce TriShGAN, under the CounteRGAN framework enhanced by the incorporation of triplet loss. This unsupervised learning approach uses distance metric learning to encourage the counterfactual explanations not only to remain close to the queried time series but also to capture the feature distribution of the instance with the desired outcome, thereby achieving a better balance between minimal cost and robustness. Additionally, we integrate a Shapelet Extractor that strategically selects the most discriminative parts of the high-dimensional queried time series to enhance the sparsity of counterfactual explanation and efficiency of the training process.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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