Co-Training-Teaching: A Robust Semi-Supervised Framework for Review-Aware Rating Regression.

Review-aware Rating Regression (RaRR) suffers the severe challenge of extreme data sparsity as the multimodality interactions of ratings accompanied by reviews are costly to obtain. Although some studies of semisupervised rating regression are proposed to mitigate the impact of sparse data, they bear the risk of learning from noisy pseudo-labeled data. In this article, we propose a simple yet effective paradigm, called co-trainingteaching (CoT²), for integrating themerits of both co-training and co-teaching toward robust semi-supervised RaRR. CoT² employs two predictors trained with different feature sets of textual reviews, each of which functions as both "labeler" and "validator." Specifically, one predictor (labeler) first labels unlabeled data for its peer predictor (validator); after that, the validator samples reliable instances from the noisy pseudo-labeled data it received and sends them back to the labeler for updating. By exchanging and validating pseudo-labeled instances, the two predictors are reinforced by each other in an iterative learning process. The final prediction is made by averaging the outputs of both the refined predictors. Extensive experiments show that our CoT² considerably outperforms the state-of-the-art recommendation techniques in the RaRR task, especially when the training data is severely insufficient. [ABSTRACT FROM AUTHOR]