Semi-supervised learning

https://www.safaribooksonline.com/library/view/apache-spark-2x/9781787126497/74757d2e-dd20-4d7a-8531-2d31716f091e.xhtml

It involves a hybrid approach of both supervised and unsupervised learning for solving a problem. The technique is to process a small set of labeled data along with a large set of unlabeled data to derive an output. Speech and image based processing utilizes this approach to solve their domain specific problems.