基于产生式集划分的上下文无关语言句子生成

给出了上下文无关文法(context-free grammar,简称CFG)产生式集的一种划分方法,可将产 生式分为两类.使用一类产生式进行推导时,推导过程将无限进行下去;使用另一类进行推导 时,推导过程将迅速结束.证明了CFG句子生成过程一定是先使用一类产生式使生成的句型不 断变长、变复杂,再使用另一类产生式使句型变成句子.据此，提出了一种可控制的通用句子 生成方法.其生成一条句子的时间和空间复杂度是O(r+n),其中n是生成句子的长度或深度 限制

Generating Sentences of CFL Based on Partition of CFG Production Set

In this paper, a method is presented to partition productions of CFG (context-f ree grammar). It divides production set into two parts. The derivation with prod uctions in one part will never terminate, while it must terminate rapidly with p roductions in the other part. It is proved that the procedure of generating sent ences of CFL (context-free language) is using productions in one part to make t he sentential form longer and more complex first, and then using productions in the other part to terminate the procedure. A general controllable method is atta ined for generating sentences of CFL with restricted length or depth. The time a nd space complexity for generating one sentence is O(r+n), where n is th e restricted length or depth of sentences and r is the number of productions in given CFG. The generating strategies for different conditions are also discu ssed.