RE: Non-deterministic content model

[Murali Mani <mani@CS.UCLA.EDU>]

yes, i think kohsuke's original example is correct... please check..

cheers - murali.

On Wed, 13 Jun 2001, Jason Chalecki wrote:

> ((a, b)*, a) essentially represents the language where the first and
> last letter is a. Additionally, if there are b's, a and b must
> alternate. So (a, (b, a)*) matches the same language and is
> deterministic, correct?
>
> However, this is a specific solution and not a general algorithm to
> transform non-deterministic to deterministic.
>
> Jason
>
>
> -----Original Message-----
> From: Murali Mani [mailto:mani@CS.UCLA.EDU]
> Sent: Wednesday, June 13, 2001 1:36 PM
> To: K.Kawaguchi
> Cc: Derek Denny-Brown; Steve Rosenberry; xml-dev@lists.xml.org
> Subject: Re: Non-deterministic content model
>
>
> Actually Kohsuke is right -- (a & b?) is *not* inherently 1-ambiguous.
>
> Also I think, the language specified by ((a, b)*, a) cannot be written
> as
> an 1-unambiguous regular expression or 1-unambiguous model group -- I
> think --
>
> when you see an "a" in the string, you do *not* know whether it is the
> first a or the second a, unless you know whether there is b following
> it.
>
> i think the above example holds for all model groups defined to date --
> thanks a lot.
>
> are there any opinions/suggestions??
>
> Derek, try to give the content model for ((a, b)*, a), if you are not
> convinced.
>
> thanks and regards - murali.
>
> On Wed, 13 Jun 2001, K.Kawaguchi wrote:
>
> >
> > > (a, b? | b?, a)
> >
> > Since the above is the equivalent of ( a | ab | ba ),
> > you can write it as
> >
> > (a,b?) | (b,a)
> >
> > which is deterministic.
> >
> > How about this?
> >
> > > (a b)* a?
> >
> >
> > I think this cannot be written by the deterministic content model.
> >
> > regards,
> > ----------------------
> > K.Kawaguchi
> > E-Mail: kohsukekawaguchi@yahoo.com
> >
> >
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