I guess I have to agree with Len about HAS-A but not because of the
containment; because of the formal XML interpretation. The [children]
Information Item says so [1].
However, an element also has [parent], [namespace name] etc information
items. Attributes have a relative set of infoitems. Isn't that a
generalized, self-contained IS-A description of a node's self?
Cheers,
Manos
[1] http://www.w3.org/TR/xml-infoset/#infoitem.element
> -----Original Message-----
> From: Bullard, Claude L (Len) [mailto:]
> Sent: Monday, April 29, 2002 6:31 PM
> To: 'Robin Cover'
> Cc: Manos Batsis;
> Subject: RE: [xml-dev] XML information modeling best practices
>
>
> We would have to agree that containment equals 'has-a'.
> What the XML containment semantic implies is up to the application
> designer. That is so. One might argue that a zero occurrence
> indicator says "might have-a".
>
> But HAS-A can be agreed upon with no extra information being
> added to the XML to indicate the agreement. IS-A can't. Or....
>
> The point is that RDF semantics are RDF semantics. I don't see
> a way out of the application IS-A application tautology. One
> shouldn't compare XML semantics to RDF semantics. One should
> understand what RDF semantics model and decide if that is
> necessary for the application at hand or if a generalized
> RDF processor (whatever it does) is doing something useful
> for the system at hand.
>
> len
>
> From: Robin Cover [mailto:]
>
> I'm not sure I agree with Len, if the claim is (?) that
> XML explicitly models HAS-A.
>
> For <foo><bar></bar></foo> we can say of the encoded
> instance that "the element foo hierarchically contains the element
> bar," but we have no authorization to believe that the
> explicit structural relationship implies HAS-A. Maybe
> bar HAS-A foo, maybe foo HAS-A bar, or maybe neither is
> true if we understand HAS-A as representing the notion of
> a property/attribute.
>
> For <parent><child></child></parent> one could mean at the
> application level that a parent has a child, or that a
> child has a parent, or neither, or any of a thousand other
> possible relationships that might be imagined; this structural
> form "A hierarchically nested in B" licenses no interpretation
> in terms of HAS-A, IS-A, IS-PART-OF, or anything else. Structurally
> XML implies notions of is-adjacent-to, precedes, follows,
> is-hierarchically-within [etc.] but a far as I know, these
> structural relationships predicated of the serial encoding
> have no authorized semantics in any domain.
>
> Or... ?
> >
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