提出可解释时间序列分类新框架,精准定位每段时序对预测的影响。
TimeSliver : Symbolic-Linear Decomposition for Explainable Time Series Classification
- 融合原始数据与符号抽象,线性编码每段时序的贡献
- 在7个数据集上比现有方法提升11%解释精度
- 兼顾高可解释性与接近顶尖模型的预测性能
准确识别每个时间片段对模型预测的影响程度,对提升模型透明度至关重要。尽管基于梯度和特征归因的后处理解释方法广受欢迎,但它们易受参考状态影响,且难以跨时间序列数据集泛化,因其将时间点独立处理,忽略序列依赖关系。另一种思路是利用模型内部可解释组件,如自注意力机制估计时间重要性,但近期研究发现注意力权重常无法真实反映时间重要性。本文提出新型可解释深度学习框架TimeSliver,联合使用原始时间序列数据及其符号抽象,构建保持原始时间结构的表示。该表示中每个元素线性编码对应时间片段对最终预测的贡献,从而为每个时间点分配有意义的重要程度评分。在7个不同合成及真实多变量时间序列数据集上,TimeSliver比其他时间归因方法高出11%。同时,在26个UEA基准数据集上,其预测性能与当前最优基线相差不超过2%,证明其在通用时间序列分类任务中兼具强大解释力与竞争力。
原文摘要 · Abstract (English)
Identifying the extent to which every temporal segment influences a model's predictions is essential for explaining model decisions and increasing transparency. While post-hoc explainable methods based on gradients and feature-based attributions have been popular, they suffer from reference state sensitivity and struggle to generalize across time-series datasets, as they treat time points independently and ignore sequential dependencies. Another perspective on explainable time-series classification is through interpretable components of the model, for instance, leveraging self-attention mechanisms to estimate temporal attribution; however, recent findings indicate that these attention weights often fail to provide faithful measures of temporal importance. In this work, we advance this perspective and present a novel explainability-driven deep learning framework, TimeSliver, which jointly utilizes raw time-series data and its symbolic abstraction to construct a representation that maintains the original temporal structure. Each element in this representation linearly encodes the contribution of each temporal segment to the final prediction, allowing us to assign a meaningful importance score to every time point. For time-series classification, TimeSliver outperforms other temporal attribution methods by 11% on 7 distinct synthetic and real-world multivariate time-series datasets. TimeSliver also achieves predictive performance within 2% of state-of-the-art baselines across 26 UEA benchmark datasets, positioning it as a strong and explainable framework for general time-series classification.
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