Thesis (M.Sc.) - Cairo University - Faculty of Computers and Information- Department of Information System

Quantication queries are an important type of queries that are used in many applications. In general, quantification queries are classified into two main categories: universal, and existential quantification queries. Both types are crucial in retrieving the results of many queries. Both universal and existential queries have gained their importance in querying traditional databases that are usually implemented on a single machine. Universal quantification is not supported directly in most database systems despite the fact that it adds significant power to a systems query processing and inference capabilities, in particular for the analysis of many-to-many relationships and of set-valued attributes. Although this is a logical feature, relational algebra does not have a direct counterpart for it, relying on rewriting it using a combination of existential quanti er and negation. However, such translation is not always possible, and even when it is, it may lead to non e cient implementations

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