Validity queries and completeness queries
The concepts of validity and completeness are defined in terms of relationship between a correct representation of the real world and the representation of the real world which is stored in a database. Here a database is understood as a Relational database, that is, a set of atomic facts. It is assumed that some users can guarantee that some parts of the database are valid, and other parts are complete. From this information, for a given standard query, are characterized a subset of the answer to the standard query which is valid, and a superset of the answer which is complete. It is guaranteed that the correct answer is bounded up and down by these two sets.
We give a formal definition of these notions in the semantics. Then we present a sound axiomatics that can be used to define a Prolog program which computes answers to validity queries and completeness queries. The axiomatics is not complete because the definition of the non standard answers involves the notion of inclusion on Relational algebra formulas. If some strong restrictions on the completeness of the axiomatics are imposed the program always terminates.
KeywordsIntelligent Information Systems Uncertainty Epistemic Logic
Unable to display preview. Download preview PDF.
- 1.B. F. Chellas. Modal Logic: An introduction. Cambridge University Press, 1988.Google Scholar
- 2.L. Cholvy, R. Demolombe, and A.J. Jones. Reasoning about the safety of information: from logical formalization to operational definition. In Proc. of 8th International Symposium on Methodologies for Intelligent Systems, 1994.Google Scholar
- 3.R. Demolombe and A. Jones. Integrity Constraints Revisited. In A. Olive, editor, 4th International Workshop on the Deductive Approach to Information Systems and Databases. Universitat Politecnica de Barcelona, 1993.Google Scholar
- 4.R. Demolombe and A. Jones. Deriving answers to safety queries. In R. Demolombe and T. Imielinski, editors, Nonstandard queries and answers. Oxford University Press, 1994.Google Scholar
- 5.A. Motro. Completeness information and its application to query processing. In Proc. of 12th International Conference on Very Large Data Bases, 1986.Google Scholar
- 6.A. Motro. Integrity = validity + completeness. ACM TODS, 14(4), 1989.Google Scholar
- 7.J. D. Ullman. Principles of Database Systems. Vol1 and Vol2. Computer Science Press, 1988.Google Scholar