Neural Networks

Chapter 4 showed how to build a simple neural network for altering the ranking of search results based on what links users have clicked in the past. That neural network was able to learn which words in which combinations were important, and also which words were unimportant to a particular query. Neural networks can be applied to both classification and numerical prediction problems.

The neural network in Chapter 4 was used as a classifier—it gave a number for every link, predicting that the link with the highest number would be the one that the user would click. Because it gave numbers for every link, you could use all the numbers to change the rankings of the search results.