Abstract
Some recursive definitions in deductive database systems can be replaced by equivalent nonrecursive definitions. In this paper we give a linear-time algorithm that detects many such definitions, and specify a useful subset of recursive definitions for which the algorithm is complete. Recent results by Gaifman et al. in “Proceedings, 2nd. IEEE Sympos. on Logic in Comput. Sci., June 1987,” pp. 106–115. show that the general problem is undecidable. We consider two types of initialization of the recursively defined relation: arbitrary initialization, and initialization by a given nonrecursive rule. This extends earlier work and is related to bounded tableau results by Sagiv in “Proceedings, ACM SIGACT-SIGMOD Sympos. on Principles of Database Systems, 1985,” pp. 171–180. Even if there is no equivalent nonrecursive definition, a modification of our algorithm can be used to optimize a recursive definition, and improve the efficiency of the compiled evaluation algorithms.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
