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On Thu, 12 Jun 2003, Michael Kay wrote:
> > Thanks for the clarification, these are the things I was
> > hoping someone could tell me, using for iterator etc, have we
> > introduced more non-closed operators?? Has someone looked at
> > them closely..?? I suspect there will be some more operators
> > of this nature in XPath 2.0..
>
> The input and output of XPath operations are constrained to be values
> described by the XPath data model. In that sense the language is closed.
> Whether the data model has the particular mathematical properties you
> are looking for is something I can't easily judge.
That is right, with respect to values they are closed. But the question is
with respect to schema.. I think this might be useful to know these
mathematical properties..??
Anyways, if someone does study all the operations of XPath, XQuery etc,
and see under what they are closed (w.r.to schema), I think it might be
useful..
cheers and regards - murali.
> There are a few glitches in terms of closure, for example I'm not very
> comfortable with the fact that the semantics of FLWR expressions in
> XQuery are defined using a notion of "tuples" which are objects that
> can't be represented directly in the data model, but overall I think
> it's pretty clean.
>
> Michael Kay
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