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Ok, thanks, let me correct it once more.. (hopefully for the last time) -- Kohsuke original one was (a, b)*, a? I would now make it a? rather than a -- now, how does it look?? Yes, you are again right about the language defined by ((a, b)*, a) being 1-unambiguous -- your regular expression is the proof.. On Wed, 13 Jun 2001, Derek Denny-Brown wrote: > > 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 -- > > (a, (b,a)*) > > It is not an 1-unambiguous model group (I think), but it is an > 1-unambiguous regular expression (I'm sure). > > Orignal RegExp -> NDFA > 0 a:1 a:2 > 1 b:0 > 2 $ > > DFA > 0' (0) a:1' > 1' (1,2) b:1' $ > > > Derek Denny-Brown > > > > > -----Original Message----- > > From: Murali Mani [mailto:mani@C...] > > Sent: Wednesday, June 13, 2001 1:36 PM > > To: K.Kawaguchi > > Cc: Derek Denny-Brown; Steve Rosenberry; xml-dev@l... > > 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@y... > > > > > > > > > ------------------------------------------------------------------ > > > The xml-dev list is sponsored by XML.org, an initiative of OASIS > > > <http://www.oasis-open.org> > > > > > > The list archives are at http://lists.xml.org/archives/xml-dev/ > > > > > > To unsubscribe from this elist send a message with the single word > > > "unsubscribe" in the body to: xml-dev-request@l... > > > > > > > >
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