The Theory of Functional and Template Dependencies
The Theory of Functional and Template Dependencies
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函数和模板依赖理论
DOI：
10.1016/0304-3975(82)90028-7
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发表时间：
1982
期刊：
影响因子：
--
通讯作者：
J. Ullman
中科院分区：
文献类型：
--
作者：
F. Sadri;J. Ullman
模板依赖由萨德里和Ullman [17]引入，以推广现有的数据依赖形式。人们希望通过研究一个大的自然类的依赖关系，我们可以解决这些依赖关系的推理问题，而这个问题是难以捉摸的模板依赖关系的有限子集，如嵌入式多值依赖关系。大约在同一时间，其他已知依赖形式的推广被开发出来，例如Fagin [11]的蕴涵依赖和Yannakakis和Papadimitriou [20]的代数依赖。与模板依赖不同，后者的形式包括函数依赖作为特殊情况。在本文中，我们表明，没有非平凡的功能依赖遵循模板依赖关系，我们的特点，这些模板依赖关系，遵循功能依赖关系。然后，我们给出了一套完整的公理推理功能和模板依赖的组合。因此，由函数依赖增强的模板依赖可以作为更一般的隐含或代数依赖的替代品，提供相同的能力来表示“自然”出现的依赖，同时提供比更一般的类更简单的符号和公理集。
Template dependencies were introduced by Sadri and Ullman [17] to generalize existing forms of data dependencies. It was hoped that by studying a large and natural class of dependencies, we could solve the inference problem for these dependencies, while that problem was elusive for restricted subsets of the template dependencies, such as embedded multivalued dependencies. At about the same time, other generalizations of known dependency forms were developed, such as the implicational dependencies of Fagin [11] and the algebraic dependencies of Yannakakis and Papadimitriou [20]. Unlike the template dependencies, the latter forms include the functional dependencies as special cases. In this paper we show that no nontrivial functional dependency follows from template dependencies, and we characterize those template dependencies that follow from functional dependencies. We then give a complete set of axioms for reasoning about combinations of functional and template dependencies. As a result, template dependencies augmented by functional dependencies can serve as a substitute for the more general implicational or algebraic dependencies, providing the same ability to represent those dependencies that appear ‘in nature’, while providing a somewhat simpler notation and set of axioms than the more general classes.