Accepted Paper: Forward and Backward Knowledge Transfer for Sentiment Classification

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Hao Wang (Southwest Jiaotong University); Bing Liu (UIC); Shuai Wang (University of Illinois at Chicago, USA); Nianzu Ma (UIC); Yan Yang (Southwest Jiaotong University)


This paper studies the problem of learning a sequence of sentiment classification tasks. The learned knowledge from each task is retained and later used to help future or subsequent task learning. This learning paradigm is called lifelong learning. However, existing lifelong learning methods either only transfer knowledge forward to help future learning and do not go back to improve the model of a previous task or require the training data of the previous task to retrain its model to exploit backward/reverse knowledge transfer. This paper studies reverse knowledge transfer of lifelong learning. It aims to improve the model of a previous task by leveraging future knowledge without retraining using its training data, which is challenging now. In this work, this is done by exploiting a key characteristic of the generative model of naive Bayes. That is, it is possible to improve the naive Bayesian classifier for a task by improving its model parameters directly using the retained knowledge from other tasks. Experimental results show that the proposed method markedly outperforms existing lifelong learning baselines.