Learning comparisons Suppose I want (the machine) to learn the ">" function, and my training set is a collection of pairs of numbers $(n_1, n_2)$ with the output True if $n_1 &gt; n_2$ and False otherwise. Which method is the most likely to work (actually, my secret goal is a form of the Netflix challenge - I have a set of $n$-tuples of real and boolean values, and I want to rank them based on some training rank data).

This has surely been studied a lot...
The classical solution is to try a one-class SVM applied only to the elements ranked above the others - you can read some papers about it looking by SVM rank or SVM ranking that will show you why that works.