  Recently, some contrastive learning methods have been proposed to
simultaneously learn representations and clustering assignments, achieving
significant improvements. However, these methods do not take the category
information and clustering objective into consideration, thus the learned
representations are not optimal for clustering and the performance might be
limited. Towards this issue, we first propose a novel graph contrastive
learning framework, which is then applied to the clustering task and we come up
with the Graph Constrastive Clustering~(GCC) method. Different from basic
contrastive clustering that only assumes an image and its augmentation should
share similar representation and clustering assignments, we lift the
instance-level consistency to the cluster-level consistency with the assumption
that samples in one cluster and their augmentations should all be similar.
Specifically, on the one hand, the graph Laplacian based contrastive loss is
proposed to learn more discriminative and clustering-friendly features. On the
other hand, a novel graph-based contrastive learning strategy is proposed to
learn more compact clustering assignments. Both of them incorporate the latent
category information to reduce the intra-cluster variance while increasing the
inter-cluster variance. Experiments on six commonly used datasets demonstrate
the superiority of our proposed approach over the state-of-the-art methods.
