[Re] GNNInterpreter: A probabilistic generative model-level explanation for Graph Neural Networks

摘要

Graph Neural Networks have recently gained recognition for their performance on graph machine learning tasks. The increasing attention on these models’ trustworthiness and decision-making mechanisms has instilled interest in the exploration of explainability tech- niques, including the model proposed in "GNNInterpreter: A probabilistic generative model- level explanation for Graph Neural Networks." (Wang & Shen (2022)). This work aims to reproduce the findings of the original paper, by investigation the main claims made by its authors, namely that GNNInterpreter (i) generates faithful and realistic explanations with- out requiring domain-specific knowledge, (ii) has the ability to work with various node and edge features, (iii) produces explanations that are representative for the target class and (iv) has a much lower training time compared to XGNN, the current state-of-the-art model- level GNN explanation technique. To reproduce the results, we make use of the open-source implementation and we test the interpreter on the same datasets and GNN models as in the original paper. We conduct an enhanced quantitative and qualitative evaluation, and additionally we extend the original experiments to include another real-world dataset. Our results show that we are not able to validate the first claim, due to significant hyperpa- rameter and seed variation, as well as due to training instability. Furthermore, we partially validate the second claim by testing on datasets with different node and edge features, but we reject the third claim due to GNNInterpreter’s failure to outperform XGNN in producing dataset aligned explanations. Lastly, we are able to confirm the last claim.