Similarity-based Contrastive Divergence Methods for Energy-based Deep Learning Models


Adepu Ravi Sankar, Vineeth N Balasubramanian ;
Asian Conference on Machine Learning, PMLR 45:391-406, 2016.


Energy-based deep learning models like Restricted Boltzmann Machines are increasingly used for real-world applications. However, all these models inherently depend on the Contrastive Divergence (CD) method for training and maximization of log likelihood of generating the given data distribution. CD, which internally uses Gibbs sampling, often does not perform well due to issues such as biased samples, poor mixing of Markov chains and high-mass probability modes. Variants of CD such as PCD, Fast PCD and Tempered MCMC have been proposed to address this issue. In this work, we propose a new approach to CD-based methods, called Diss-CD, which uses dissimilar data to allow the Markov chain to explore new modes in the probability space. This method can be used with all variants of CD (or PCD), and across all energy-based deep learning models. Our experiments on using this approach on standard datasets including MNIST, Caltech-101 Silhouette and Synthetic Transformations, demonstrate the promise of this approach, showing fast convergence of error in learning and also a better approximation of log likelihood of the data.

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