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From: anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups: comp.compilers
Subject: Re: How detect cycle in grammar ?
Date: Tue, 22 Nov 2011 15:20:06 GMT
Organization: Institut fuer Computersprachen, Technische Universitaet Wien
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Keywords: parse, design
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Xref: x330-a1.tempe.blueboxinc.net comp.compilers:348

Gene <gene.ressler@gmail.com> writes:
>Nonterminals that can never derive a terminal string are the
>problem.

Is it really?  Since they cannot derive a terminal, they have no
influence on the language described by the grammar.  They might just
as well not be there.  Are they really a problem (except for certain
implementation techniques)?

- anton
--
M. Anton Ertl
anton@mips.complang.tuwien.ac.at
http://www.complang.tuwien.ac.at/anton/