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Re: Non-deterministic content models

• To: Jeni Tennison <jeni@j...>
• Subject: Re: Non-deterministic content models
• From: Eric van der Vlist <vdv@d...>
• Date: 15 Jul 2003 12:31:31 +0200
• Cc: xml-dev@l...
• In-reply-to: <48691020885.20030715111931@j...>
• Organization: Dyomedea (http://dyomedea.com)
• References: <3.0.6.32.20030715055242.01069350@p...> <20030715040539.GD17627@m...> <1058247974.26014.54.camel@delleric> <48691020885.20030715111931@j...>

Hi Jeni,

On Tue, 2003-07-15 at 12:19, Jeni Tennison wrote:
> Hi Eric,
> 
> > I have recently written (with much help from Murata Makoto) a
> > chapter dedicated to Relax NG, ambiguous and non-deterministic
> > models proposing a distinction between determinism and unambiguity
> > and showing some more examples:
> >
> > http://books.xmlschemata.org/relaxng/RngBookAssignment.html
> 
> Nice chapter! 

Thanks!

> On the "what to do about ambiguity" front, you mention
> adding an except pattern and using explicit disambiguation rules. A
> third option would be to use type systems that support you saying
> "this value is *both* X and Y".
> 
> For instance, you give the example:
> 
>   element foo { xs:boolean | xs:integer }
> 
> If you have: <foo>3</foo>, the XPath 2.0 type system will happily say
> that <foo> is of type xs:integer, and of type xs:decimal (since all
> xs:integers are xs:decimals).
> 
> If you had: <foo>1</foo>, you could have a type system that says that
> <foo> is of type xs:boolean, and of type xs:integer, and of type
> xs:decimal.
> 
> You can think of this as multiple inheritance (a new, anonymous, type
> is inherited from both xs:boolean and xs:integer, and the <foo>
> element ends up either being a xs:boolean or an xs:integer, or this
> new anonymous type). A language that used such a type system would
> have to use the usual methods for disambiguation (such as those you
> list in your chapter) in situations where polymorphic operators or
> functions were used with such a type.

Yes, that'd be a nice thing to investigate. I *suspect* that it would be
more complicated to report by schema processors but I haven't done
enough work in implementing type assignment to be 100% sure. 

I'll add this as a third option for sure!

> But anyway... one thing you mentioned in your chapter but I wondered
> if you could expand on was the impact of ambiguity and non-determinism
> on guided editing. I'd always thought that it was non-determinism that
> made guided editing hard (and that this was one of the reasons XSD
> didn't support non-deterministic content models), but you seem to
> suggest that it's ambiguity that causes the problem. Could you explain
> a bit more?

Yes, I think that I should elaborate more on the impact on existing
tools. I'll do some tests with xmloperator [1] which AFAIK is the only
XML editor using Relax NG for guided editing and add my conclusions to
the chapter! 

[1] http://www.xmloperator.net/

Thanks

Eric
> Cheers,
> 
> Jeni
> 
> ---
> Jeni Tennison
> http://www.jenitennison.com/
> 
> 
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-- 
Tired to type XML tags?
                                                       http://wikiml.org
------------------------------------------------------------------------
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 - August 4th (Montreal, Canada)  http://makeashorterlink.com/?U28A217A4
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Eric van der Vlist       http://xmlfr.org            http://dyomedea.com
(W3C) XML Schema ISBN:0-596-00252-1 http://oreilly.com/catalog/xmlschema
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• References:
  • Non-deterministic content models
    • From: Gustaf Liljegren <gustaf.liljegren@b...>
  • Re: Non-deterministic content models
    • From: John Cowan <cowan@m...>
  • Re: Non-deterministic content models
    • From: Eric van der Vlist <vdv@d...>
  • Re: Non-deterministic content models
    • From: Jeni Tennison <jeni@j...>

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