1. A method, in an information handling system comprising a processor and a memory, of identifying cluster relationships for searching across a plurality of corpora, the method comprising: identifying, by the system, a plurality of different cluster classifications for a corresponding plurality of corpora; classifying, by the system, entity information from documents stored in the plurality of corpora into the plurality of different cluster classifications by extracting named entities, terms, contexts, and concepts from the documents, and assigning the named entities, terms, contexts, and concepts to at least one of the plurality of different cluster classifications; applying semantic analysis, by the system, to identify entity relationships between entity information classified in the plurality of different cluster classifications by applying shallow and deep semantic analysis methods to identify entity relationships between the plurality of different cluster classifications; determining, by the system, one or more scores for each identified entity relationship; identifying, by the system, a cluster relationship between at least two cluster classifications based on the one or more scores for each identified entity relationship; and searching, by the information handling system, at least first and second corpora corresponding to the at least two cluster classifications having the identified cluster relationship.