Using Relaxation Techniques to Evaluate Queries in Deductive Databases
Relaxation method is a general framework used to improve the efficiency of answering a query q(a, x) given to a deductive database P. It first solves problem (q′ (a′, x′), P RLX ) where P RLX is a relaxation of the original database P and q′(a′, x′) is the modified query to P RLX , to derive a set PREL of predicate occurrences that is known to contain the answer set ANS in P, and construct database P MDF by augmenting P with the restriction that solution space is constrained to PREL, and finally solves problem (q( a, x), P MDF ) to get the desired answer set ANS. If the relaxation P RLX is properly defined, (q′(a ′, x ′), P RLX ) can be efficiently solved since P RLX is simpler than P, and (q ( a, x), P MDF ) can also be efficiently solved as the solution space is restricted. Several methods are proposed to construct such relaxations. It is also argued that the original form of magic set method  can be described in the context of the relaxation method.
KeywordsRelaxation Method Original Database Deductive Database Extensional Predicate Intensional Predicate
Unable to display preview. Download preview PDF.
- F.Bancilhon,: Naive Evaluation of Recursively Defined Relations, On Knowledge Base Management Systems—Integrating Database and AI Systems, Blodie and Mylopoulous, Eds., Springer-Verlag, Berlin, pp. 165–178, 1985.Google Scholar
- F.Bancilhon, D.Maier, Y.Sagiv and J.Ullman,: Magic sets and other strange ways to implement logic programs, Proc. 5th ACM SIGMOD-SIGACT Symp. on Principles of Database System(PODS), 1986 Google Scholar
- F.Bancilhon and R.Ramakrishnan,: An amateur’s introduction to recursive query processing strategies, Proc. ACMSIGMOD Conf. on Management of Data(SIGMOD), Washington,D.C., 1986. Google Scholar
- C.Beeri and R..Ramakrishnan,: On the power of magic, Proc. 6th ACM SIGACT-SIGMOD-SIGART Symp. on Principles of Database Systems(PODS), San Diego, Calif., 1987. Google Scholar
- A.V.Gelder,: A Message Passing Framework for Recursive Query Evaluation, Proc. SIG-MOD. 1986 Google Scholar
- E.Lozinskii,: Evaluating Queries in Deductive Databases by Generating, Proc. 11th Int. Joint Conf. on Artificial Intelligence. 1985. Google Scholar
- D.Mckay and S.Shapiro,: Using Active Connection Graphs for Reasoning with Recursive Rules, Proc. 7th Int. Joint Conf. on Artificial Intelligence. 1981 Google Scholar
- J.F.Naughton, R.Ramakrishnan, Y.Sa.giv and.J.D.Ullman,: Argument Reduction by Factoring, Proc. VLDB, pp.173–182, 1989. Google Scholar
- R.Ramakrishnan,: Magic templates: A spellbinding approach to logic programsProc. 5th Int. Conf. and Symp. on Logic Programming(ICLP/SLP), Seattle, Wash.. 1988. Google Scholar
- J.Rohmer, R.Lescoeur and J.M.Kerisit,: The Alexander method, a technique for the processing of recursive axioms in deductive database, New Generation Computing 4(3), 1986. Google Scholar
- H.Seki,: On the power of Alexander templates, Proc. 8th ACM SIGACT-SIGMOD-SIGART Symp. on Principles of Database Systems(PODS), Philadelphia, Penn., 1989. Google Scholar
- L.Vieille,: Recursive axioms in Deductive Databases. The Query/Subquery Approach, Proc. First Int. Conf. on Expert Database Systems, Charleston, 1986 Google Scholar