提出全局图反事实解释新方法,让拒绝样本通过少量通用改造变为接受结果。
COMRECGC: Global Graph Counterfactual Explainer through Common Recourse
- 设计算法COMRECGC,生成适用于所有拒绝图的通用改造方案。
- 在4个真实图数据集上验证,优于现有基线方法,且改造幅度小。
- 适合需要可操作建议的场景,如药物发现与生物计算。
图神经网络(GNN)广泛应用于社交网络、分子生物学和推荐系统等领域。为缓解其黑箱特性,研究者提出了多种解释方法,主要分为事实型与反事实型两类。针对二分类任务中的‘拒绝’图,全局反事实解释的目标是生成一组少数‘接受’图,使所有输入的‘拒绝’图都能通过转化成为‘接受’图,这种转化称为‘救济路径’。若一组救济路径能覆盖所有‘拒绝’图,则称其为‘通用救济路径’。尽管局部反事实解释已得到充分研究,但针对GNN的全局通用救济路径问题仍待探索。本文首次形式化该问题,并提出有效算法COMRECGC求解。在四个真实世界图数据集上评估,COMRECGC表现优于多个强基线。对比传统图反事实解释,本方法生成的通用救济路径要么相当,要么更优,因此在药物发现与计算生物学等应用中具有重要价值。
原文摘要 · Abstract (English)
Graph neural networks (GNNs) have been widely used in various domains such as social networks, molecular biology, or recommendation systems. Concurrently, different explanations methods of GNNs have arisen to complement its black-box nature. Explanations of the GNNs' predictions can be categorized into two types--factual and counterfactual. Given a GNN trained on binary classification into ''accept'' and ''reject'' classes, a global counterfactual explanation consists in generating a small set of ''accept'' graphs relevant to all of the input ''reject'' graphs. The transformation of a ''reject'' graph into an ''accept'' graph is called a recourse. A common recourse explanation is a small set of recourse, from which every ''reject'' graph can be turned into an ''accept'' graph. Although local counterfactual explanations have been studied extensively, the problem of finding common recourse for global counterfactual explanation remains unexplored, particularly for GNNs. In this paper, we formalize the common recourse explanation problem, and design an effective algorithm, COMRECGC, to solve it. We benchmark our algorithm against strong baselines on four different real-world graphs datasets and demonstrate the superior performance of COMRECGC against the competitors. We also compare the common recourse explanations to the graph counterfactual explanation, showing that common recourse explanations are either comparable or superior, making them worth considering for applications such as drug discovery or computational biology.
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