Weakness: 1. Regarding the adaptive masking part, the authors' work is incremental, and there have been many papers on how to do feature augmentation, such as GraphCL[1], GCA[2]. The authors do not experiment with widely used datasets such as Cora, Citeseer, ArXiv, etc. And they did not compare with better baselines for node classification, such as GRACE[3], GCA[2], MVGRL[4], etc. I think this part of the work is shallow and not enough to constitute a contribution. The authors should focus on the main contribution, i.e., graph-level contrastive learning, and need to improve the node-level augmentation scheme. 2. In the graph classification task, the compared baseline is not sufficient, such as MVGRL[4], gpt-gnn[5] are missing. I hope the authors could add more baselines of graph contrastive learning and test them on some common datasets. 3. I am concerned whether the similarity-aware positive sample selection will accelerate GNN-based encoder over-smoothing, i.e., similar nodes or graphs will be trained with features that converge excessively and discard their own unique features. In addition, whether selecting positive samples in the same dataset without introducing some perturbation noise would lead to lower generalization performance. The authors experimented with the transfer performance of the model on the graph classification task, though it still did not allay my concerns about the model generalization. I hope there will be more experiments on different downstream tasks and across different domains. Remarks: 1. The authors seem to have over-compressed the line spacing and abused vspace. 2. Table 5 is collapsed.
[1] Y. You, T. Chen, Y. Sui, T. Chen, Z. Wang, and Y. Shen, “Graph contrastive learning with augmentations,” Advances in Neural Information Processing Systems, vol. 33, 2020. [2] Y. Zhu, Y. Xu, F. Yu, Q. Liu, S. Wu, and L. Wang, “Graph contrastive learning with adaptive augmentation,” arXiv preprint arXiv:2010.14945, 2020. [3] Y. Zhu, Y. Xu, F. Yu, Q. Liu, S. Wu, and L. Wang, “Deep graph contrastive representation learning,” arXiv preprint arXiv:2006.04131, 2020. [4] Hassani, Kaveh, and Amir Hosein Khasahmadi. "Contrastive multi-view representation learning on graphs." International Conference on Machine Learning. PMLR, 2020. [5] Hu, Ziniu, et al. "Gpt-gnn: Generative pre-training of graph neural networks." Proceedings of the 26th ACM SIGKDD International Conference on Knowledge Discovery & Data Mining. 2020.
3. I am concerned whether the similarity-aware positive sample selection will accelerate GNN-based encoder over-smoothing, i.e., similar nodes or graphs will be trained with features that converge excessively and discard their own unique features. In addition, whether selecting positive samples in the same dataset without introducing some perturbation noise would lead to lower generalization performance. The authors experimented with the transfer performance of the model on the graph classification task, though it still did not allay my concerns about the model generalization. I hope there will be more experiments on different downstream tasks and across different domains. Remarks: