Editing Context-free grammar (section)

== Linguistic applications ==
[[Noam Chomsky|Chomsky]] initially hoped to overcome the limitations of context-free grammars by adding [[transformational grammar|transformation rules]].<ref name="chomsky1956"/>

Such rules are another standard device in traditional linguistics; e.g. [[grammatical voice|passivization]] in English. Much of [[generative grammar]] has been devoted to finding ways of refining the descriptive mechanisms of phrase-structure grammar and transformation rules such that exactly the kinds of things can be expressed that natural language actually allows. Allowing arbitrary transformations does not meet that goal: they are much too powerful, being [[Turing complete]] unless significant restrictions are added (e.g. no transformations that introduce and then rewrite symbols in a context-free fashion).

Chomsky's general position regarding the non-context-freeness of natural language has held up since then,<ref name="shieber1985">{{citation | title=Evidence against the context-freeness of natural language | year=1985 | last=Shieber | first=Stuart | journal=Linguistics and Philosophy | volume=8 | pages=333–343 | url=http://www.eecs.harvard.edu/~shieber/Biblio/Papers/shieber85.pdf |archive-url=https://web.archive.org/web/20040415200116/http://www.eecs.harvard.edu/~shieber/Biblio/Papers/shieber85.pdf |archive-date=2004-04-15 |url-status=live | doi=10.1007/BF00630917 | issue=3| s2cid=222277837 }}.</ref> although his specific examples regarding the inadequacy of context-free grammars in terms of their weak generative capacity were later disproved.<ref name="pullum-gazdar1982">{{citation | title=Natural languages and context-free languages | year=1982 | last=Pullum | first=Geoffrey K. | author2=Gerald Gazdar | journal=Linguistics and Philosophy | volume=4 | pages=471–504 | doi=10.1007/BF00360802 | issue=4| s2cid=189881482 }}.</ref> [[Gerald Gazdar]] and [[Geoffrey Pullum]] have argued that despite a few non-context-free constructions in natural language (such as [[cross-serial dependencies]] in [[Swiss German]]<ref name="shieber1985"/> and [[reduplication]] in [[Bambara language|Bambara]]<ref name="culy1985">{{citation | title=The Complexity of the Vocabulary of Bambara | year=1985 | last=Culy | first=Christopher | journal=Linguistics and Philosophy | volume=8 | pages=345–351 | doi=10.1007/BF00630918 | issue=3| s2cid=189881984 }}.</ref>), the vast majority of forms in natural language are indeed context-free.<ref name="pullum-gazdar1982"/>