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Re: Fwd: OWL Test Cases and Species Validation

From: Guus Schreiber <schreiber@cs.vu.nl>
Date: Thu, 28 Aug 2003 00:00:04 +0100
Message-ID: <3F4D37F4.1000906@cs.vu.nl>
To: Sean Bechhofer <seanb@cs.man.ac.uk>
Cc: Jim Hendler <hendler@cs.umd.edu>, webont <www-webont-wg@w3.org>, Jeremy Carroll <jjc@hpl.hp.com>

Response wrt. point 2.

Sean Bechhofer wrote:

> On Tue, 26 Aug 2003, Jim Hendler wrote:

>>>> 2)
>>>>
>>>> Test case:
>>>> http://www.w3.org/2002/03owlt/miscellaneous/Manifest102
>>>> Input document:
>>>> http://www.w3.org/2002/03owlt/miscellaneous/consistent102
>>>>
>>>> The manifest declares the input as an OWL DL document.  In section
>>>>8.3 of the OWL Web Ontology Language Reference (regarding use of
>>>>owl:intersectionOf in OWL Lite documents) it says:
>>>>
>>>> “owl:intersectionOf be used only on lists of length greater than
>>>>one that contain only named classes and restrictions”
>>>>
>>>> This would appear to be the case for the input document, the
>>>>object of the owl:intersectionOf triple is a list of length greater
>>>>than one containing only restrictions.  I think the input document
>>>>is an OWL Lite document and the test case should be changed
>>>>accordingly.
> 
> 
> Section 4.1 of S&AS details the mapping rules that translate abstract
> syntax to triples. Examination of the table shows that there are only
> three ways in which an intersectionOf triple can occur:
> 
> 1) Due to a class definition
> 
> 	Class(classID [Deprecated] partial
>       		annotation_1 ... annotation_m
> 		description_1 ... description_n)
> 
> 2) Due to an intersectionOf expression
> 
> 	intersectionOf(description_1 ... description_n)
> 
> 3) Due to a restriction with multiple components:
> 
> 	restriction(ID component_1 ... component_n)
> 
> Now 2) and 3) are only available in OWL DL (See Section 2.3 of S&AS). So
> for an intersection to be valid in an OWL-Lite document, it must have come
> from the translation of a class definition, and (from the right hand side
> of the table in 4.1) it must therefore be the case that the subject of the
> intersectionOf triple is a classID. This is *not* the case in
> miscellaneous/consistent102, as the subject of the intersection is a blank
> node. So the ontology is not Lite.
> 
> I guess the upshot of this is that the restriction listed in section 8.3
> of Reference is not quite strong enough -- it is not only the case that
> intersectionOf be used only on lists of length greater than one that
> contain only named classes and restrictions -- in addition intersectionOf
> cannot apply to blank nodes.

Sec. 8.3 of Reference also contains the following constraint on OWL Lite 
(see just below the intersectionOf bullet):

[[
* the object of rdf:type triples be named classes or restrictions;
]]

so Ref is correct wrt. the test (102 has a blank node as object of 
rdf:type).

Having said that, there could be room for improving the description of 
the Lite restrictions. However, I do not agree with Jeremy's proposed 
response:

Jeremy Carroll wrote:
http://lists.w3.org/Archives/Public/www-webont-wg/2003Aug/0122.html
> 2)
> http://www.w3.org/2002/03owlt/miscellaneous/consistent102
> 
> The file is in OWL DL not OWL Lite.
> 
> An analysis of sections 2 and 4 of S&AS shows that in OWL 
 > Lite there are no blank nodes of type owl:Class.

The last statement is incorrect, as Lite allows (only) blank nodes of 
type owl:Restriction, a subclass of owl:Classs. Note also that the 
mapping rules for restrictions in Sec. 4.2 of S$AS have an optional 
"rdf:type owl:Class" triple. Therefore I propose to add the following 
statement to Ref, Sec. 83.

[[
Blank nodes representing classes should be of type owl:Restriction.
]]

and adapt the response accordingly.

The addition is just for clarity: it is already implied by the 
constraints listed in 8.3.

Guus

> 
> Cheers,
> 
> 	Sean
> 

-- 
Free University Amsterdam, Computer Science
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E-mail: schreiber@cs.vu.nl
Home page: http://www.cs.vu.nl/~guus/
Received on Wednesday, 27 August 2003 18:59:59 GMT

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