Editing Transformational grammar (section)

====Mathematical representation====
An important feature of all transformational grammars is that they are more powerful than [[context-free grammar]]s.<ref>{{cite journal|last=Peters|first=Stanley|author2=R. Ritchie|year=1973|title=On the generative power of transformational grammars|url=http://www.cs.utoronto.ca/~gpenn/csc2517/peters-ritchie73.pdf|journal=Information Sciences|volume=6|pages=49–83|doi=10.1016/0020-0255(73)90027-3}}</ref> Chomsky formalized this idea in the [[Chomsky hierarchy]]. He argued that it is impossible to describe the structure of natural languages with context-free grammars.<ref>{{cite journal|last=Chomsky|first=Noam|year=1956|title=Three models for the description of language|url=http://www.chomsky.info/articles/195609--.pdf|url-status=dead|journal=IRE Transactions on Information Theory|volume=2|issue=3|pages=113–124|doi=10.1109/TIT.1956.1056813|s2cid=19519474 |archive-url=https://web.archive.org/web/20100919021754/http://chomsky.info/articles/195609--.pdf|archive-date=2010-09-19}}</ref> His general position on the context-dependency of natural language has held up, though his specific examples of the inadequacy of CFGs in terms of their weak generative capacity were disproved.<ref>{{cite journal|last=Shieber|first=Stuart|year=1985|title=Evidence against the context-freeness of natural language|url=http://www.eecs.harvard.edu/~shieber/Biblio/Papers/shieber85.pdf|journal=Linguistics and Philosophy|volume=8|issue=3|pages=333–343|doi=10.1007/BF00630917|s2cid=222277837}}</ref><ref>{{cite journal|last=Pullum|first=Geoffrey K.|author2=Gerald Gazdar|year=1982|title=Natural languages and context-free languages|journal=Linguistics and Philosophy|volume=4|issue=4|pages=471–504|doi=10.1007/BF00360802|s2cid=189881482}}</ref>