Department of Linguistics, University of Tuebingen, Wilhelmstrasse 19, Tuebingen 72074, Germany. gerhard.jaeger@uni-tuebingen
Philos Trans R Soc Lond B Biol Sci. 2012 Jul 19;367(1598):1956-70. doi: 10.1098/rstb.2012.0077.
The first part of this article gives a brief overview of the four levels of the Chomsky hierarchy, with a special emphasis on context-free and regular languages. It then recapitulates the arguments why neither regular nor context-free grammar is sufficiently expressive to capture all phenomena in the natural language syntax. In the second part, two refinements of the Chomsky hierarchy are reviewed, which are both relevant to the extant research in cognitive science: the mildly context-sensitive languages (which are located between context-free and context-sensitive languages), and the sub-regular hierarchy (which distinguishes several levels of complexity within the class of regular languages).
本文第一部分简要概述乔姆斯基层次的四个级别,特别强调了上下文无关和正则语言。然后,它总结了为什么正则和上下文无关语法都不足以表达自然语言语法中的所有现象的论点。在第二部分,回顾了乔姆斯基层次的两个改进,它们都与认知科学的现有研究相关:轻度上下文敏感语言(位于上下文无关和上下文敏感语言之间)和次正则层次(在正则语言类中区分几个复杂度级别)。