Sat, 09 Jun 2007 08:52:08 -0300

Related articles |
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What is the complement of context free language? lijh_vc@yahoo.com.cn (jianhua li) (2007-06-04) |

Re: What is the complement of context free language? bagnara@cs.unipr.it (Roberto Bagnara) (2007-06-09) |

Re: What is the complement of context free language? tk@ic.unicamp.br (Tomasz Kowaltowski) (2007-06-09) |

Re: What is the complement of context free language? elsheikhmh@gmail.com (Mustafa Elsheikh) (2007-06-09) |

From: | Tomasz Kowaltowski <tk@ic.unicamp.br> |

Newsgroups: | comp.compilers |

Date: | Sat, 09 Jun 2007 08:52:08 -0300 |

Organization: | IC/UNICAMP |

References: | 07-06-006 |

Keywords: | theory, parse |

Posted-Date: | 09 Jun 2007 10:23:30 EDT |

*> In many text books, they say that the complememt of context free*

*> language us not context free language . But they do not say the*

*> complemet of CFL is context sensitive language or Recursively*

*> enumerable language ? So what is the language of the complement of*

*> context free language?*

The complement of a CFL is obviously not only recursively enumerable but

also recursive. Given a CF grammar G, it is easy to imagine a Turing

machine which checks if a given input string belongs to L(G); if so,

reject reject the input, if not, accept it.

-- tk

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