The ability to deal with a huge number of independent and heterogeneous repositories is the most critical problem in Global Information Systems. One approach to enable efficient query processing is by utilizing semantic descriptions (organized as ontologies) of such repositories whenever available.
In this context semantic relationships among ontologies can be used Query Processors. Three kind of relationships are considered: synonyms and hypernyms. Using synonyms the semantic of the query is preserved; however, when synonyms are not available and hypernyms or hyponyms are used there exists some loss of information that must be measured.
& Sheth, A. P.
(1996). Managing Multiple Information Sources through Ontologies: Relationship between Vocabulary Heterogeneity and Loss of Information. CEUR Workshop Proceedings, 4, 50-52.