Conjunctive Queries Determinacy and Rewriting
The problem of whether a set of queries on a database provides enough information for answering another query has received considerable attention in different contexts related to data management. This has been a central topic in data integration where the problem is formulated in terms of rewriting a specific query using a given set of queries, called views. The same problem is encountered in semantic caching, when answers to a given set of queries are stored in a cached data container. When a new query arises, it must be determined whether the query can be answered from the cache, or the complete database needs to be interrogated.