Oh, It was written "ethanol" and I read "hydrogen" .... my bad /o\

Anyway, metaclasses are a way to solve this kind of paradoxes.

Lets say we got a class <alcohol types>.

This class would have, amongst its instances, the <ethanol> class.

But a basic principle of ontologies (philosophically) is the token/type distinction ( https://en.wikipedia.org/wiki/Type%E2%80%93token_distinction ), description logic are based on it, so also the OWL ontologies. Like Daniel said, this distinction discriminates token, real world object or events, and classes of this kind of objects. Abstract objects like ethanol are classes in this view. Its token are all the concrete ethanol molecules there exists.

To be consistent with your model we also can see the class of classes <alcohol types>, then <methanol> is an instance of it.

The beauty of things here is that we can do both :) If we accept that item can have both instance of and subclass of claims.

2014-09-25 21:32 GMT+02:00 Thomas Douillard <thomas.douillard@gmail.com>:
This is about chemical compounds, molecules. Here it's about atoms, I think. Correct me if I have wrong information, but afaik CheBi has no chemical elements class, so there is no real answer to the original question.

But yes, those classes if they are not already on Wikidata seems OK to have, and subclass of is appropriate as its semantics is the same in Chebi and in Wikidata.


2014-09-25 20:07 GMT+02:00 Benjamin Good <ben.mcgee.good@gmail.com>:
Based on the CHEBI ontology perspective, alcohol is a class with subclasses like 'aromatic alcohol' which has subclasses like 'benzyl alcohols' which has subclasses like 'methylbenzyl alcohol' and so on.

These relationships seem worth capturing and subclass seems like a reasonable way to do it.  If not, would another property be better?


-Ben

  

On Thu, Sep 25, 2014 at 10:52 AM, Alain Cuvillier <alain.cuvillier@gmail.com> wrote:
Hi all,

why are both the subclass of and instance of properties set for the ethanol (showcase) item?
For me ethanol is a single concrete alcohol and it is not a class. There is only one ethanol, with a single chemical formula and structure, so only the instance of property is right for this item ?


Thank you
Alain


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