The paper describes a new learning procedure, termed back-propagation, intended for networks composed of neuron-like units. Core Mechanism and Goal The primary function of this procedure is to repeatedly adjust the weights of the connections within the network. The goal of these iterative adjustments is to minimize a measure of the difference between the network's actual output vector and the desired output vector. Key Feature: Internal Representations The critical aspect of back-propagation is its ability to determine the weight adjustments for internal 'hidden' units. These hidden units are connections that are not part of the input or output layer, but are fundamental for the network to form powerful internal representations. Mathematical Foundation and Significance The learning rule for modifying the weights of these internal units is derived from the chain rule for ordered derivatives. The ability of back-propagation to create useful new features through hidden units distinguishes it from earlier, simpler methods, such as the perceptron convergence procedure. Motivation The overall objective of the research is to find a powerful, dynamic modification rule that allows an arbitrarily connected neural network to develop an appropriate internal structure specific to a particular task domain. The network's task is formally defined by providing the desired state vector of the output units for each state vector presented to the input units. If the output units clearly convey the difference between the actual and desired outputs, finding learning rules to adjust the connection strengths is relatively straightforward. Learning becomes more challenging when the introduction of hidden units makes the required internal structure less obvious. The procedure aims to successfully reduce the difference between the actual and desired output vectors through learning.
{
"id": "95a0e7fd-04a1-449f-8b76-651999d01098",
"title": "Learning Representations by Back-Propagating Errors (1986)",
"slug": "learning-representations-by-back-propagating-errors",
"video_url": "https://www.youtube.com/watch?v=MZnUSsTUuTY",
"url": "https://www.iro.umontreal.ca/~vincentp/ift3395/lectures/backprop_old.pdf",
"resource_category": "research",
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