Joint unsupervised contrastive learning and robust GMM for text clustering

Text clustering aims to organize a vast collection of documents into meaningful and coherent clusters, thereby facilitating the extraction of valuable insights. While current frameworks for text clustering try to minimize the anisotropy of pre-trained language models through contrastive learning of text embeddings, the approach of treating in-batch samples as negatives is suboptimal. The K-means algorithm offers a way to sample both hard negatives and false negatives. However, relying solely on a single measure of semantic similarity between distribu-tions and using coarse-grained weighting for negative pairs may potentially limit performance. Furthermore, considering the very similar distribution in text clusters due to rich semantics, the Mahalanobis distance-based Gaussian Mixture Model (GMM) is prone to falling into local optima due to one Gaussian model, having a smaller weight, may gradually merging into another during the parameter evaluation by the EM algorithm. To tackle these challenges, we propose a model named JourTC: Joint unsupervised contrastive learning and robust GMM for Text Clustering. In the contrastive learning phase, hard negatives, potential false negatives, and their corresponding global similarity-aware weights are determined through posterior probabilities derived from a Robust GMM (RGMM). This RGMM utilizes the entropy of each individual Gaussian model as a metric and adaptively adjusts the posterior probabilities of samples based on the Gaussian models with both maximum and minimum entropy to diminish the influence of low-entropy Gaussian models. Extensive experiments have shown that JourTC can be seamlessly integrated into existing text clustering frameworks, leading to a notable improvement in accuracy. Our code is publicly available.1