Journal of Computer Science and Technology

, Volume 7, Issue 4, pp 356–362 | Cite as

A study of optimization and Rule/Goal Graph for a logical query

  • Tianzhu Li
Regular Papers


Static optimization of logical queries is, in substance, to move selections down as far as possible in evaluating logical queries. This paper extends Ullman's RGG (Rule/Goal Graph)[6] and introduces P-graph, with which a wide range of recursive logical queries can be statically optimized top-down and evaluated bottom-up, some of which are usually optimized by dynamic approaches. The paper also shows that for some logical queries the complexity of pushing selections down and computing bottom-up is related to the complexity of base relation in the queries.


Compatible Condition Sequential Machine Logical Query State Subset Recursive Rule 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Science Press, Beijing China and Allerton Press Inc. 1992

Authors and Affiliations

  • Tianzhu Li
    • 1
  1. 1.Computing CenterHebei UniversityBaoding

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