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Neural Comput. 2006 Jul;18(7):1527-54.

A fast learning algorithm for deep belief nets.

Author information

1
Department of Computer Science, University of Toronto, Canada. hinton@cs.toronto.edu

Abstract

We show how to use "complementary priors" to eliminate the explaining-away effects that make inference difficult in densely connected belief nets that have many hidden layers. Using complementary priors, we derive a fast, greedy algorithm that can learn deep, directed belief networks one layer at a time, provided the top two layers form an undirected associative memory. The fast, greedy algorithm is used to initialize a slower learning procedure that fine-tunes the weights using a contrastive version of the wake-sleep algorithm. After fine-tuning, a network with three hidden layers forms a very good generative model of the joint distribution of handwritten digit images and their labels. This generative model gives better digit classification than the best discriminative learning algorithms. The low-dimensional manifolds on which the digits lie are modeled by long ravines in the free-energy landscape of the top-level associative memory, and it is easy to explore these ravines by using the directed connections to display what the associative memory has in mind.

PMID:
16764513
DOI:
10.1162/neco.2006.18.7.1527
[Indexed for MEDLINE]

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