函数依赖结构与演绎图

Deduction Graphs Based-on Functional Dependency Structure

本文论证了函数依赖与无函数 Horn 公式之间的等价性,并提出了基于函数依赖结构的演绎图,为逻辑查询及推理处理提供了一个新方法,它与运用规则的次序无关,因而具有很多相应的好处。

A deduction graph(DG)for representing the structural relationship between functional dependencies(FD)or functional-free Horn formula(extended from Horn classes)in a relational database or rule-based expert system is defined.In addition to graphically solving the inference problem by DG's,many logic queries can be answered by DG's with substitutions for unifying expressions.This graphic approach provides an alternative method for conducting inferences and processing logic queries,which is neither forward-chaining-oriented nor backward-chaining- directed using the inference rule of resolution and has many advantages to execute a logic program,These advantages are achieved because a DG is never infinite and constructing a DG is independent from the computation and search rules and also independent from the order of the given FD's or HC's.