Fig. 2. Illustration of BYOL and BYOL for hierarchical BEHRT.
BYOL (top) includes four components, data augmentation, encoder, projector, and predictor. Both online and target network have a similar model architecture. BYOL for hierarchical BEHRT (bottom) has similar framework, the segment augmentation corresponds to the augmentation in BYOL (top), and the segment augmentation is conducted on temporal features extracted by local feature extractor.