TL-PLSA: Transfer Learning between Domains with Different Classes

A new transfer learning method is presented in this paper, addressing a particularly hard transfer learning problem: the case where the target domain shares only a subset of its classes with the source domain and only unlabeled data are provided for the target domain. This is a situation that occurs frequently in real-world applications, such as the multiclass document classification problems that motivated our work. The proposed approach is a transfer learning variant of the Probabilistic Latent Semantic Analysis (PLSA) model that we name TL-PLSA. Unlike most approaches in the literature, TL-PLSA captures both the difference of the domains and the commonalities of the class sets, given no labelled data from the target domain. We perform experiments over three different datasets and show the difficulty of the task, as well as the promising results that we obtained with the new method.