8. The method of claim 7 , wherein generating a user-specific ontology includes generating the one or more edges that connect the one or more vertices, wherein each defined ontology includes one or more edges that connect one or more vertices, and wherein the determining a degree of similarity includes for each defined ontology of the plurality of defined ontologies, identifying a set intersection in accordance with the one or more edges and one or more vertices in the user-specific ontology and the one or more edges and one or more vertices in the respective defined ontology.
7. The method of claim 6 , further including: selecting a defined ontology of the plurality of ontologies having the highest degree of similarity to the user-specific ontology; and determining a category corresponding to the selected defined ontology, wherein the categorizing the user includes categorizing the user as a member of the determined category.