12. The system of claim 9 , wherein the processor is further configured to: determine, for each of the plurality of topics, related topics, wherein a distance measure between a topic and a related topic is calculated; determine a plurality of topic clusters, wherein one or more of the plurality of topics and one or more related topics are placed in a topic cluster based on the distance measure; map the user interest profile to at least one of the plurality of topic clusters to determine user cluster features; and determine a conjunction that models interaction between the determined user cluster features and the plurality of content items.
12. The system of claim 9 , wherein the processor is further configured to: determine, for each of the plurality of topics, related topics, wherein a distance measure between a topic and a related topic is calculated; determine a plurality of topic clusters, wherein one or more of the plurality of topics and one or more related topics are placed in a topic cluster based on the distance measure; map the user interest profile to at least one of the plurality of topic clusters to determine user cluster features; and determine a conjunction that models interaction between the determined user cluster features and the plurality of content items. 13. The system of claim 12 , wherein the plurality of topic clusters are determined using hierarchical agglomerative clustering.