Concepts are things like Astronomy,
Bernard Vatant wrote:
> Ed
>
> Be careful
> to represent something as a skos:Concept if you want to use it this way,
> and as a owl:Class if you need a cllass (I won't repeat myself too much
> ...). Then use consistent realtionships, subclassOf for classes, and
> BT-NT for concepts.
If it is to be in OWL, then every Thing is a Class. Some of these
Classes are Concepts, meaning not a physical Thing. So math, history,
astronomy, leverage, dualism, opposition are Concepts. Concepts can be
subclassed. Perhaps broader and narrower should only allow Concepts in
their range. I have to think about that some more.
>
>> As for the specific example of white dwarf and Chandrasekhar limit
>> (CL). In OWL you can restrict the WhiteDwarf to have Mass hasValue
>> (maxValue hasValue CL). The CL is an instance of MassLimit.
>> MassLimit are a subClassOf Mass. Measurements have property sci:of,
>> which allows restriction: "CL of WhiteDwarf".
>
> Maybe this works. I would like to see the formal OWL code, though
> (please reply privately, I don't think the list needs to see that gory
> things). Having Mass as a class with individual instances sounds weird
> ... OK. I don't want to go into a detailed modeling discussion, but I'm
> afraid that before you achieve widespread understanding, let alone
> consensus, on such representation for all possible astronomical
> concepts, you'll be a very old man, and will have pile up such complex a
> model that no one will ever dare use it in real life. :-)
I don't understand the reason for pessimism. Astronomers already share
considerable common knowledge of the terms. Any dictionary of astronomy
specifies in more detail than an ontology the meaning of astronomical
terms. I do not hear widespread dissent that these dictionaries have it
all wrong. If you mean folks won't understand the specific set of rdf
triples, I don't see that we can't all understand and agree that a
specific layout of this knowledge in simple three word sentences is
faithful to the dictionaries. We will argue over what is the optimal
arrangement, but optimization can be delayed.
>
>> The question then is, do you bother to mention that CL and WhiteDwarf
>> are also SKOS:related?
>
> Because I will not index my docs/data with an instance of the "Mass"
> class! I will index with a simple Thesaurus concept, simply "related to"
> the white dwarf concept, without needing a reasoner to figure this
> relationship out of a convoluted restriction of the maximal value of
> some property on some class!
> I will need other, simpler representations of the same "natural" concepts.
>
It is deja vu all over again. This is just the Topic Maps vs Ontology
debate which has been a raging for years. I happen to take the side of
Ontology. When you add a relatedTo, you are making a subjective
statement because everything is related. Is a white dwarf related to
Giant Stars because they evolve directly into white dwarfs? Is a G
Dwarf Star related because it ends its life as a white dwarf. What
about Conduction, the major mechanism for white dwarfs to cool and
therefore to radiate? Binary Stars? Where does it end? Can you ever
get consensus among astronomers on what is or is not "related to" a
white dwarf?
Nevertheless, I am fine with a starter ontology that has relatedTo
relationships just to get the terms quickly in. As we have time, we can
add more specific information that clarifies the relatedTo.
Ed
Received on 2007-09-24Z21:42:02