[Reading] Support Vector Learning for Ordinal Regression

"Learning to rank" is automatically creating a ranking function that assigns scores to instances, then rank the instances by using the scores.

This paper formalizes learning to rank as a problem of binary classification, and uses SVM (support vector machine) to learn the binary classifier. This formulation minimizes pair-wise 0-1 loss.

The learned ranking function can be viewed as (1)Ranking function: given an example, output its ranking score. (2)Classifier: given a pair of instances, output their relative ranking.