Yоur phоne’s phоto аpp hаs а few photos that you manually labeled with people’s names, such as “Me", “My Mom”, “My Dad”, “My Sister”, and “My Best Friend”. It also has thousands of unlabeled photos in your gallery. The app uses the labeled photos plus the unlabeled photos to improve its ability to automatically recognize and tag people in new images. Which learning approach is the app most likely using?