16 Jan 2004 22:58:10 -0500

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What is the trick of SLL(k) grammars subset LL(k) grammars for k>1 oliver@zeigermann.de (Oliver Zeigermann) (2004-01-16) |

From: | Oliver Zeigermann <oliver@zeigermann.de> |

Newsgroups: | comp.compilers |

Date: | 16 Jan 2004 22:58:10 -0500 |

Organization: | T-Online |

Keywords: | parse, LL(1) |

Posted-Date: | 16 Jan 2004 22:58:10 EST |

This is the sequel of me asking trivial questions and getting very

smart answers I do not understand which makes me yell at people ;)

Today's problem is how come every SLL(1) grammar is an LL(1) grammar

*and* the other way round, while this is not true for k>1. For k>1

SLL(k) grammars are a subset of LL(k). An example of an LL(2) grammar

which is not SLL(2) taken from Grune/Jacobs (this time lower case

letters are terminals):

S -> aAaa | bAba

A -> b | lambda

I have a problem with the proof given in Grune/Jacobs. I have no

objections and understand every step taken, but still have no

*intuition* why all this is true.

Thanks for any hints. Any - no - this is no homework, I am just an

all-purpose programmer who really is interested :)

Oliver

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