17. The method according to claim 16 , wherein identifying the commonalities comprises matching an entity that occurs in the ontologies of two or more of the spheres.
16. A method for data access, comprising: receiving in a computer multiple ontologies, each ontology pertaining to a respective sphere of knowledge and including a structured vocabulary of entities, types of the entities and relations between the entities; automatically identifying commonalities between the ontologies; based on the commonalities, building a super-ontology containing elements that are common to multiple spheres of the knowledge; and automatically defining an ontology for a specific sphere of knowledge based on the super-ontology.