| A Study of Optimization and Rule/Goal Graph for a Logical Query |
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| 引用本文： | Li Tianzhu. A Study of Optimization and Rule/Goal Graph for a Logical Query[J]. 计算机科学技术学报, 1992, 7(4): 356-362. DOI: 10.1007/BF02943552 |
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| 作者姓名： | Li Tianzhu |
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| 作者单位： | CmputingCenter,HebeiUniversity,Baoding071002 |
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| 摘 要： | 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 Pgraph,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.
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| 关 键 词： | 自动推理 逻辑询问 优化 规则图 目标图 |
A study of optimization and Rule/Goal Graph for a logical query |
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| Tianzhu Li. A study of optimization and Rule/Goal Graph for a logical query[J]. Journal of Computer Science and Technology, 1992, 7(4): 356-362. DOI: 10.1007/BF02943552 |
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| Authors: | Tianzhu Li |
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| Affiliation: | Computing Center Hebei University Baoding; |
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| Abstract: | 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. |
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