Effective semi-supervised learning algorithms based on pretraining techniques (Hinton and Salakhutdinov, 2006;Bengio et al., 2007;Erhan et al., 2010) have been developed for text classification, deep belief networks (Hinton and Salakhutdinov, 2006), and stacked autoencoders Bengio et al., 2007).
the core difference between self-training algorithms is in the second step: data sampling policy.