[antlr-interest] Re: antlr vs. sableCC comparison

[Terence Parr]

On Sunday, May 25, 2003, at 03:18  PM, Oliver Zeigermann wrote:

> --- In antlr-interest at yahoogroups.com, Terence Parr <parrt at j...>
>>> You can always left factor, so LL(k) can never
>>> describe a language you can not describe by LL(k-1).
>>
>> Actually I believe there are *languages* that are LL(k) but not
>> LL(k-1).  The same is not true for LR.  LR(k) is same as LR(k-1)
>> languages and grammars.  Just saw that lemma in a book I think ;)
>>
>
> This makes me curious. Can you give an example for a language that
> is LL(k), but not LL(k-1).

Not without my theory book at the office ;)

>  Also, what about my theoretical argument
> above? If it is not convincing, where lies my mistake?

I think that the above statement is probably false, hence, the truth of 
the lemma in that book ;)  I'll look it up...I'm frankly ashamed I 
don't know this by heart!  Well, I used to know stuff, but now I'm 
dumberer ;)

Ter
Co-founder, http://www.jguru.com
Creator, ANTLR Parser Generator: http://www.antlr.org
Co-founder, http://www.peerscope.com link sharing, pure-n-simple
Lecturer in Comp. Sci., University of San Francisco


 

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