Patent attributes
In one embodiment, a method includes deriving input topics based on a content item, generating a matrix of scores for the input topics according to a first set of cross-indexed topics, where each of the scores indicates a degree of similarity between a corresponding one of the input topics and a corresponding one of the first cross-indexed topics, calculating a total score for each of the first cross-indexed topics based on the scores for the first cross-indexed topic across all of the input topics, and selecting one or more of the first cross-indexed topics based on the total scores of the first cross-indexed topics. Deriving the input topics may include using a topic tagger to identify the topics based on the content item. The first set of cross-indexed topics may be generated from a database of topics, such as an online encyclopedia.