Re: converting this grammar to LL1

"Joachim Durchholz" <joachim_d@gmx.de>
7 Nov 2002 00:50:14 -0500

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From: "Joachim Durchholz" <joachim_d@gmx.de>
Newsgroups: comp.compilers
Date: 7 Nov 2002 00:50:14 -0500
Organization: Compilers Central
References: 02-10-097 02-10-103 02-11-015
Keywords: parse, LL(1)
Posted-Date: 07 Nov 2002 00:50:14 EST

Te-Cheng Shen wrote:
>
> The problem is "How do I know the modified grammar generate the SAME
> language as the original one?"


This is indeed a problem. Unfortunately, there is no algorithm to decide
whether two grammars generate the same language.


> Or I should ask this question "Is there any algorithm to make this
  > kind of ambiguity go away?" I am NOT asking for very general
  > algorithms which can translate ANY ambiguous grammar to
> umanbiguous ones because they might not exist.


I don't know what kinds of ambiguities exist. It might be interesting to
have a classification of common ambiguities and how they can be safely
resolved that go beyond the canonical operator-precedence rules.


Regards,
Joachim

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