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Re: SubObjectPropertyChain question

From: Xiaoshu Wang <wangxiao@musc.edu>
Date: Fri, 09 Mar 2007 22:16:00 -0500
Message-ID: <45F222F0.6070000@musc.edu>
To: Evren Sirin <evren@clarkparsia.com>
CC: public-owl-dev@w3.org

Sirin,

> Note that, these definitions do not have a meaning in OWL-DL. Both 
> rdfs:subsPropertyOf and rdf:List (as other built-in vocabulary) are 
> considered to be part of syntax in OWL-DL.
Hmm...I am not sure I understand this.  From my understanding, 
rdfs:subPropertyOf and rdf:List are not the "syntactic construct" like 
the rdf:Description.  They are the actual semantic constructs.  
Otherwise, an RDF parser has to treat "rdfs:subPropertyOf" differently, 
and it seems to me that breaks the backward compatibility.
>> I wonder if it be cleaner to translate this as an Axiom.  For 
>> instance, define a term called owl11:ObjectPropertyChainAxiom and 
>> assign it two property "propChain" which ranges over an rdf:List and 
>> a superProp ranges over an Object.  So it would be something like
>>
>> _:x rdf:type owl11:ObjectPropertyChainAxiom;
>>      owl11:propChain T(SEQ p1, ... pn).
>>      owl11:superProp op.
> With a different motivation, sometime ago I suggested the following 
> alternative syntax (possibly with different keywords):
>
> <owl11:PropertyChain>
>  <owl11:members rdf:parseType="Collection">
>       <owl11:ObjectProperty rdf:ID="p1"/>
>        ...
>   </owl11:members>
>   <rdfs:subPropertyOf rdf:resource="#p"/>
> </owl11:PropertyChain>
This works fine with me except that I don't think the 
<rdfs:subPropertyOf/> should be used.  The reason is the same as I 
raised before, it will suggest <owl:PropertyChain> is a rdf:Property, 
which is not, because the chain is a composition of properties.  Use 
another property name will make it separate cleanly.
>> Another question about the document is why all collection is 
>> transformed to rdf:List.  Most should be a BAG.  In RDF/XML, writing 
>> a list is quite cumbersome, but for BAG, parsetype="Collection" can 
>> be used.  I wonder it is just a careless of writing or is there a 
>> reason that rdf:List must be used?
> I think there is a confusion here because parseType="Collection" is 
> used for rdf:Lists. The only requirement is that the list be an object 
> of a triple. However, the current specification maps the rdf:List to a 
> subject position which makes it impossible to use 
> parseType="Collection".  With a different encoding (like the one you 
> or I suggest) it would be possible to use parseType. Even though we 
> think RDF/XML is not for humans to look at, sometimes it is inevitable 
> (sigh!) and I think these kind of shortcuts would be useful.
Oh, is it (that parseType can be used for rdf:List)?  I thought the 
ordering of subelement of a parseType="Collection" is arbiturary. (Or it 
will used for rdf:Seq, rdf:Bag, rdf:Alt) but work for rdf:List as well?

Xiaoshu
Received on Saturday, 10 March 2007 03:16:20 GMT

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