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Re: [xml-dev] RE: Abstraction in Science, Mathematics, Software, and Markup

Maybe there is an (extended) XSD meta-meta-type akin to the OWL
'Thing' which is completely abstract with every possible 'has-a' and
every possible 'is-a'. Maybe it could be logically defined (according to
Roger's 'crossProduct' proposal) crossProductThing to which every
can have an 'is-a' relationship. In UBL we had a concept in the early
days of what we called an 'Ur-type' (after the city Ur from which
supposedly every language developed?). That seems to be similar.

These levels of abstraction do seem to have parallels in the ISO CCTS
implemented by languages such as UBL which then provides the data
dictionary naming conventions.

Stephen D Green

On 12 March 2011 23:14, Michael Kay <mike@saxonica.com> wrote:
> On 12/03/2011 10:34, Costello, Roger L. wrote:
>> Hi Stephen,
>>> Are you suggesting or even hinting that it should be possible
>>> to define a type whose contents are types rather than elements?
>> Funny you should ask! Yes!
>> A couple weeks ago I pitched that very idea on the xmlschema-dev list:
> Well, "complexType" and "simpleType" are the names of two types whose
> instances are types - the set of complexTypes and the set of simpleTypes
> respectively. I guess Roger's "cross-product" is another type whose
> instances are types, though he presented it more as a constructor for new
> types, akin to construction-by-list and construction-by-union.
> The IRDS model from the 1980s had four layers: loosely, objects like "John
> Smith", types like "Person", meta-types like "Complex Type", and
> meta-meta-types like "Concept". The things in each layer are instances of
> the types in the layer above. The idea was that the meta-meta-types were
> fixed (they define the ontological framework), but the meta-types are
> completely extensible - the idea being that you can always incorporate new
> "data models" like the relational model, the XML model, etc.
> I put "data model" in quotes, because one of the problems is that the term
> is used by some people to mean a set of types like "Person", and by others
> to mean a set of meta-types like "Complex Type".
> Michael Kay
> Saxonica
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