Re: Linkbases, Topic Maps, and RDF Knowledge Bases -- help me

[uche.ogbuji@fourthought.com]

John Cowan (on the mark, as usual):

> Here's my take on it, which surely is not complete and may not be
> 100% correct.  By "resources" I mean the W3C sense: anything which
> has an URI.
>
> 1) RDF expresses *binary relations* between *resources*, and also relations
> between a resource and a literal string.

Yes, but it does provide a mechanism for expressing N-ary relationships,
and at a certain conceptual level, an N-ary relationship is simply an
specialized arrangement of binary relationships.

The argument I've most heard against this is that it is inefficient, but I
think this is only a problem is you take RDF's serialization model too
literally in your code.  There is no reason not to directly model N-ary
relationships in an RDF system to gain efficiency.

> 2) XLink expresses *multi-way* relations (with role labels) between
> resources, and also specifies preferred traversal paths (arcs) between
> the related resources.
>
> 3) XTM expresses multi-way relations (with role labels) between
> *topics*, where topics represent subject matters, which may be either
> themselves resources or non-addressable objects (like people) who can
> be described by resources.

XTM is really a higher-layer level, as you say, of N-ary relationships
which can be implemented using RDF and XLink, althrough based on my recent
expereinces, there's no doubt to me that RDF is the superior tool for
a Topic Maps basis, which is why Eric van der Vlist's work

http://xmlhack.com/read.php?item=1108

Is a good thing.  I've often talked about developing an RTM, but my itch
has not been great enough to scratch.  Eric's paved the way here.


-- 
Uche Ogbuji                               Principal Consultant
uche.ogbuji@fourthought.com               +1 303 583 9900 x 101
Fourthought, Inc.                         http://Fourthought.com
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