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Roger L. Costello wrote:
>
> That got me to thinking. Suppose that we define the collection of all
> XML tags that are used within a domain as a "system". Let me refer to
> each individual tag as a "part" of the system. The system is
> dynamically expanding and shrinking, i.e., parts (tags) are being
> introduced/withdrawn all the time. There are both fixed and changing
> interactions in the system, i.e., some parent/child, sibling, semantic
> relationships are fixed, others change.
>
> What we have is a complex system. I could continue on with this
> description and talk about system properties, emergent properties,
> attractors, etc.
But, Roger, it is not a complex, self-organizing system in your sense
because there is no feedback between the names within one of these
documents or even the domain. Changes and feedback come from _people_,
not from the names and documents.
> However, since the topic is semantics, I would like to
> focus on the use of ontologies in such a system.
>
> Ontology languages such as RDF Schema and OWL provide the ability to
> *statically* capture semantic relationships. However, as Mike points
> out, semantics is a continually evolving thing. As a system evolves, so
> must the ontology evolve.
Right. There is an obvious analogy to the difference between static
class diagrams and an actual running program.
In fact, an ontology must be part of the
> system.
>
> "The essence of self-organization is that system structure often appears
> without explicit pressure or involvement from outside the system."[1]
> To manage evolving semantics a system must self-organize as semantics
> evolve. In other words, an ontology must be a constantly evolving
> entity.
>
> How can we create an ontology that evolves? Here is a thought: express
> semantic relationships in an XSLT document! An XSLT stylesheet has an
> interesting property of being able to output a modified version of
> itself, i.e., the output of the stylesheet is another, modified,
> stylesheet. The output stylesheet may contain template rules that have
> been modified to reflect changing semantics, and additional template
> rules that contain new semantic relationships.
Once again, these templates will change because of the action of people,
not because they do it instrinsically (overnight while no one is
watching, perhaps!).
But your paragraph does raise a fascinating possibility - perhaps there
could be specially designed stylesheets that can in fact propagate after
a fashion - an xslt analog to Conway's Game of Life. It boggles the
mind. And you know, it has been shown that you can build NOR and NAND
gates in the Game of Life, so theoretically you could simulate a general
purpose computer. So maybe one could do the same with the XSLT Game of
Transforming Life. Hmm, that would put a new meaning on the claim that
xslt is Turing complete!
Hey, this could be more fun than xml haiku.
>
> Honestly, I am not sure how one would express semantic relationships in
> a stylesheet. For example, how would you express that a SLR is a type of
> Camera, or aperture is synonymous with f-stop?
>
But to what end? You can already express those thing in OWL/RDF, so why
reinvent the wheel? If you want transforms in the mix, you can just
have a 2-stage process by which a stylesheet transforms an OWL/RDF
document at every turn of the wheel, right?
Cheers,
Tom P
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