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Re: ACTION-264: Discuss imports with Tim Redmond.

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Tue, 17 Feb 2009 10:22:06 +0000
Message-Id: <781C7EF0-87BF-47B1-82BB-C6A468174467@cs.man.ac.uk>
Cc: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>, "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>, Bijan Parsia <bparsia@cs.manchester.ac.uk>, Alan Ruttenberg <alanruttenberg@gmail.com>, public-owl-wg@w3.org
To: Timothy Redmond <tredmond@stanford.edu>
Ok, I still don't understand.

On 16 Feb 2009, at 19:31, Timothy Redmond wrote:

> I wanted to make a further clarification.  I am not particularly  
> worried  about  the data structures that ontology tools use to
> guide the IO redirection for imports.  What  I don't like is the  
> fact that in OWL 2.0, the meaning of an  imports statements  can
> only be resolved through I/O calls.

How are these not related?

>   There is no way to determine the meaning of an imports directive  
> by looking  at the contents of
> the imports  closure alone.

I would have thought that an imports closure is a post-parsing  
concept, thus you, in fact, can determine the meaning, since IO calls  
have been resolved.

>   These I/O calls may behave  differently at different sites in  
> different circumstances.

I don't get it.

> In contrast, according to the direct semantics, in OWL 1.0, the  
> imports statement has a meaning  based on the contents of the  
> ontologies.
> If I go to the OWL 1.0 direct semantics document and search for  
> imports, I find the following statement:
>
>> Aside from this local meaning, an owl:imports annotation also  
>> imports the contents of another OWL ontology into the current  
>> ontology. The imported ontology is the one, if any, that has as  
>> name the argument of the imports construct. (This treatment of  
>> imports is divorced from Web issues. The intended use of names for  
>> OWL ontologies is to make the name be the location of the ontology  
>> on the Web, but this is outside of this formal treatment.)
>
> This fact has been exploited  by the owl api.  It  makes sharing of  
> ontologies easier because the meaning of imports can be
> determined even  if the IO operations cannot succeed.

How? If you don't have the imported ontology, you don't.

>   Protege 4 uses this fact to access the TONES ontologies.

I don't see how that works.

>   This seems
> like a very useful feature of the language.

In my experience it was a bane :)

> In OWL 2.0, the imports statement is not mentioned in the direct  
> semantics.  I think that this is because  the meaning of the imports
> statement is divorced from the contents of the ontologies.

I don't understand.

> On Feb 16, 2009, at 5:43 AM, Ian Horrocks wrote:
>> Just to be clear, I assume we are talking about recommendation in  
>> the usual sense and not in the W3C sense.
>
> Yes - I think I agree.
>
>> Even in this case, I think that recommending this particular  
>> solution may be too strong. Suggesting it should be OK though.
>
> I am  still looking at exactly what is being suggested here.  My  
> first reaction, after looking at the XML catalog documents, was  
> that the
> idea was to map the iri being imported to the location of the  
> imported ontology in a repository.

For example.

> Thus for the imports statement
>
> 	X imports http://purl.org/obo/owl/PATO
>
> the XML  Catalog would map
>
> 	http://purl.org/obo/owl/PATO to file:./quality.owl
>
> where quality.owl is the location of the Phenotypic quality  
> ontology on disk.  As I thought about it, I am  not sure that this  
> would be particularly
> useful.

Really? It seems to solve most problems.

>   It might be great for a particular tool but it seems like it   
> will depend on many assumptions that get in  the way of sharing  
> ontologies.
[snip]

How so? XML Catalogs can be shared.

Cheers,
Bijan.
Received on Tuesday, 17 February 2009 10:18:38 GMT

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