14. A system for searching for content in a target set of content based on a reference set of content, a reference semantic network representing knowledge associated with the reference set of content, and a target semantic network representing knowledge associated with the target set of content, the system comprising: at least one processor configured to perform a method comprising: receiving a user-specified search query; obtaining, by using at least one processor executing stored program instructions, at least one concept semantically relevant to the user-specified search query by using the target semantic network and the reference semantic network; constructing a second search query by augmenting the first search query with one or more terms associated with the at least one obtained concept; providing, to the at least one user, content associated with search results obtained based at least in part on searching the target set of content by using the second search query, wherein any concept in the semantic network is represented by a data structure storing data associated with a node in the semantic network.
24. The system of claim 14 , wherein the target semantic network is represented by a data structure embodying a directed graph comprising a plurality of nodes and a plurality of edges, wherein each node is associated with a concept and an edge between two nodes represents a relationship between the two corresponding concepts.