  Contrastive learning has been widely studied in sentence representation
learning. However, earlier works mainly focus on the construction of positive
examples, while in-batch samples are often simply treated as negative examples.
This approach overlooks the importance of selecting appropriate negative
examples, potentially leading to a scarcity of hard negatives and the inclusion
of false negatives. To address these issues, we propose ClusterNS
(Clustering-aware Negative Sampling), a novel method that incorporates cluster
information into contrastive learning for unsupervised sentence representation
learning. We apply a modified K-means clustering algorithm to supply hard
negatives and recognize in-batch false negatives during training, aiming to
solve the two issues in one unified framework. Experiments on semantic textual
similarity (STS) tasks demonstrate that our proposed ClusterNS compares
favorably with baselines in unsupervised sentence representation learning. Our
code has been made publicly available.
