
OWL 2 Came Out Today - _pius
http://www.w3.org/TR/owl2-overview/
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mark_l_watson
I have to admit that I find more value in just using RDF and RDFS, along with
simple to install and admin RDF data stores like Sesame, and perhaps Redland
(nice, but does not fully support RDFS inferencing).

Something that works for me is always keeping Sesame running (and OpenCyc, but
mostly for learning/experimenting - I have never done anything practical with
OpenCyc, after years of playing with it) on a server on my LAN at home. If you
always have a RDF data store available, then it is easier to use it as an
alternative to a relational database, if that is appropriate for a project.

Anyway, I like "semantic web 'light'" :-)

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wsprague
Here is how to say "NY", according to the wiki article on RDF:

<rdf:RDF xmlns:rdf="<http://www.w3.org/1999/02/22-rdf-syntax-ns#>
xmlns:dcterms="[http://purl.org/dc/terms/>](http://purl.org/dc/terms/>);
<rdf:Description rdf:about="urn:x-states:New%20York">
<dcterms:alternative>NY</dcterms:alternative> </rdf:Description> </rdf:RDF>

hehe. That's funny...

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gchpaco
That actually says something slightly different, defining NY as an alternative
for New York. But yes, the RDF syntax is terrible. Turtle was my favorite.

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m0th87
Honest question: does anyone actually /use/ OWL? My only experience with it
was in a class, and it seemed to me like a very verbose and overly-complicated
way of describing some pretty simple stuff.

~~~
gchpaco
All general purpose ontologies look like very verbose and overly-complicated
ways of describing things. OWL is no different, and the fact that it has taken
on the challenge of relating several different preexisting ontologies to each
other complicates it further.

Now, that doesn't mean it's useful. The largest ontological framework I'm
aware of is Cyc, which uses its own proprietary ontology and is at least as
complex as OWL ever was or will be. Ultimately I think it's about as useful as
reasoning about RDF ever is, which is to say not very at this time--but that's
not really its fault.

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eob
You're comparing Apples and Oranges a bit. OWL is formal framework that can be
used to describe ontologies. Cyc is an attempt to create an ontology that
describes the world.

You are right that a lot of these "glob everything together" ontologies
inevitably get too unwieldy to actually use. And wouldn't be so far off saying
that OWL itself is a bit hard to grok. But it is important to see what the
difference is. What is important about something like OWL, OWL-DL, or OWL
Light is that they specify the _types of axioms_ you are allowed to use. For
example, the following statements are very different:

\- Humans have exactly two biological parents

\- Humans must have biological parents

\- Humans must have biological parent(s)

\- Humans can have parent(s)

OWL, and its subsets, are attempts to carve out logical axioms that allow you
to specify the nature of conceptual classes and their properties. You need a
framework such as OWL to spell out what you are allowed to state about
concepts like this because different types of logical relationships have
algorithmic complexity implications. What you are allowed to state is
incredibly important to people who want to perform logical inference, for
example, because certain types of axioms will take a dataset on which
inference would otherwise be O(P) time, and turn it to O(NP) time.

