Re: a or b or both - mystery..

[Marcus Carr <mrc@allette.com.au>]

Murali Mani wrote:

> I think you know that TREX is from James Clark, and I think James Clark
> strongly believes in non-deterministic content models for ease of use.

Is "ease of use" the main motivation for allowing non-deterministic models in
TREX? As these problems seem even less frequent in XML than they did in SGML, this
seems not to buy a whole lot.

> PS: The issues are not just expressiveness when you get to document
> processing, but closure properties are *very* important, and it gets
> really messy as XML Schema is *not* closed under 99% of the operations
> that anyone will need.

You clearly understand this stuff a lot better then I do, so please interpret any
questions as curiousity rather than a challenge to your points. To whom are
closure properties important? What proportion of developers will be impacted by
the lack of closure, and what will the ramifications be? Do the restrictions on
queries due to lack of closure result in processing inefficiencies, or something
more dire? Would you term this as a wide issue, or a narrower one that you're
looking at very closely?

> I am not sure whether I should give this, but I think this is a decently
> prepared report, written largely by my friend, but it is my work also, I
> think some people might find it useful -- it is available at
> http://www.cs.ucla.edu/~mani/xml/papers/conferences/WebDB2001/td-main2.ps

It looks very interesting, but it would help me if I understood the scope of the
issues better. Thanks for your patience.


--
Regards,

Marcus Carr                      email:  mrc@allette.com.au
___________________________________________________________________
Allette Systems (Australia)      www:    http://www.allette.com.au
___________________________________________________________________
"Everything should be made as simple as possible, but not simpler."
       - Einstein