A Deep Dive into Training Algorithms for Deep Belief Networks

Abstract

Deep Belief Networks (DBNs) have emerged as powerful tools for feature learning, representation, and generative modeling. This paper presents a comprehensive exploration of the various training algorithms employed in the training of DBNs. DBNs, composed of multiple layers of stochastic hidden units, have found applications in diverse domains such as computer vision, natural language processing, and bioinformatics. The paper begins by delving into the pre-training phase, where Restricted Boltzmann Machines (RBMs) play a central role. We review the Contrastive Divergence (CD) and Persistent Contrastive Divergence (PCD) algorithms, shedding light on their strengths and weaknesses in initializing deep networks. Emphasis is placed on their applicability to different data types and scales. Moving to the fine-tuning stage, the paper explores the use of backpropagation with gradient descent, discussing modern optimization techniques, including stochastic gradient descent and adaptive learning rate methods. We also examine regularization techniques like dropout and weight decay to address overfitting concerns. Furthermore, we discuss architectural variants of DBNs, such as Convolutional Deep Belief Networks (CDBNs) for image data and Recurrent DBNs for sequential data. We highlight the adaptation of DBNs for specific tasks, including classification, regression, clustering, and generative modeling.