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Re: [pointless:Partiles:Structure]: i cannot understand this phrase...

From: Martin Gudgin <marting@develop.com>
Date: Wed, 18 Jul 2001 17:38:12 -0700
Message-ID: <000101c11003$c02d5ff0$a4f36f3f@greyarea>
To: "choi jongwon" <jwchoi@digiweb21.com>, "Henry S. Thompson" <ht@cogsci.ed.ac.uk>
Cc: <www-xml-schema-comments@w3.org>

----- Original Message -----
From: "Henry S. Thompson" <ht@cogsci.ed.ac.uk>
To: "choi jongwon" <jwchoi@digiweb21.com>
Cc: <www-xml-schema-comments@w3.org>
Sent: Saturday, July 07, 2001 7:20 AM
Subject: Re: [pointless:Partiles:Structure]: i cannot understand this
phrase...


> "choi jongwon" <jwchoi@digiweb21.com> writes:
>
> > this question is about pointless of Partiles in Structure spec.
> >
> > 3.9.6
> >  ...
> >  Schema Component Constraint: Particle Valid(Restriction)
> >  ...
> >  ...
> >  <choice>
> >   One of the following must be true:
> >   2.2.1 {particles} is empty "and the particle within which this
<choice> appears has {min occurs} of 0. "
> >   2.2.2 All of the following must be true:
> >    2.2.2.1 The particle within which this <choice> appears has {max
occurs} and {min occurs} of 1.
> >    2.2.2.2 One of the following must be true:
> >     2.2.2.2.1 The <choice>'s {particles} has only one member.
> >     2.2.2.2.2 The particle within which this <choice> appears is itself
among the {particles} of a <choice>.
> >
> >  in above 2.2.1,
> >  i cannot understand why "and the particle within which this <choice>
appears has {min occurs} of 0." is appended...
> > "{particles} is empty" is not enough?..
>
> Because <choice/> is unsatisfiable.  It's like AND and OR considered
> as n-ary functions:
>
>   AND() is true ; including <sequence/> as a required part of a
>                   content model does not change what it validates
>
>   OR() is false ; including <choice/> as a required part of a content
>                   model ensures that it never validates anything
>
> So for <choice/> to be pointless, it must be optional.

I don't get this at all... I don't understand what you mean by n-ary
functions in this context. It seems very strange that <choice/> is
unsatisfiable. Can you elaborate please?

Regards

Martin Gudgin
DevelopMentor
Received on Wednesday, 18 July 2001 23:36:38 GMT

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