【摘要】 通过对具体文法的分析 ,定义了上下文无关文法中非终止符的相似性概念 ,提出了判定算法 ,并证明 :若两个非终止符的相似性达到一定程度 ,那么它们必定等价。利用上述结论 ,最终得到了一个判断上下文无关文法语言相同的充分性条件更多还原

【Abstract】 This paper defines the similarity of the concepts in the context-free grammar, puts forward an algorithm for judging the similarity and proves that two non-terminal labels must be equivalent if the similarity between them gets to some extent by analyzing the sample grammar.At last, this paper presents a sufficient condition for judging the equivalence of context-free grammars based on the conclusions mentioned above.更多还原