[Q] LL(1) Grammers and Ambig.

calius@netvision.net.il (Nitzan Shaked)
18 Oct 2000 23:51:26 -0400

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[Q] LL(1) Grammers and Ambig. calius@netvision.net.il (2000-10-18)
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From: calius@netvision.net.il (Nitzan Shaked)
Newsgroups: comp.compilers
Date: 18 Oct 2000 23:51:26 -0400
Organization: NetVision Israel
Keywords: parse, LL(1), question


In the chapter on LL(1), the Dragon Book doesn't state so but I think
that ambig. grammars will cause a multiple entry in the LL(1) Table,
which of course would be a problem for the parser. As a matter, I
think I have a proof of that. Am I right on that?

Also: ambig. grammars are a "sufficient but not necessary" condition
for multiple entries to happen. What other conditions will cause that?
On that subject, I think it might be grammars that were once
left-recursive (some, not all of them).

And finally: then dragon book (p. 191, at the bottom) states that "... this
grammar is ambig., and the ambig. is manifested by the doulbe entry...".
Assuming I *do* have a double entry, how would I go about finding a word
which has two lm derivations, in order to show the ambig. (if one exists)?


Nitzan Shaked Zapex Research
Video Conf. & Codecs Group Manager

Tel: (ext 258) +972-9-8658570
Fax: +972-9-8851112
Email: nitzans@zapex.co.il
Web: http://www.zapex.co.il

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