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Re: comments on RDF mapping

From: Ian Horrocks <Ian.Horrocks@comlab.ox.ac.uk>
Date: Tue, 23 Oct 2007 14:59:05 +0100
Message-Id: <213409F6-628D-49C8-BB0D-EA2683D759B7@comlab.ox.ac.uk>
Cc: Jeremy Carroll <jjc@hpl.hp.com>, public-owl-wg@w3.org
To: Jim Hendler <hendler@cs.rpi.edu>

The stated intention of the OWL 1.1 design is that any OWL DL  
document is also an OWL 1.1 document, and thus no migration will be  
necessary. (Of course there may be bugs in the spec that need to be  
fixed in order to make this be true. ) Note, e.g., that in Table 7,  
as well as mapping <x owl11:equivalentObjectProperty y> to  
EquivalentObjectProperties( OP(x) OP(y) ), there is also a mapping  
that takes care of backwards compatibility by mapping <x  
owl:equivalentProperty y> to EquivalentObjectProperties( OP(x) OP 
(y) ) in case both x and y are object properties, i.e., OnlyOP(x) =  
true and OnlyOP(y) = true.

Now that I look at this again, I already see one (trivial) bug -- in  
the case of subPropertyOf, the backwards compatibility mapping  
wrongly says x owl11:subObjectPropertyOf y when it should, of course,  
say x rdfs:subPropertyOf y.

In spite of this bug, I think you will find that the previously  
mentioned OWL 1.1 enabled tools are perfectly happy to process OWL  


On 23 Oct 2007, at 14:17, Jim Hendler wrote:

> One thing what would help me a lot, and maybe reduce some of my  
> confusion would be if there was a single table somewhere of all the  
> vocabulary terms that will now be in OWL, perhaps with a * as to  
> which ones are syntactic sugar.  As far as I can tell from the  
> current document, most of my existing OWL would be no longer DL,  
> since it lacks type information, and there'd be a lot of new  
> vocabulary items to learn to fix it -- but I can't really evaluate  
> this because it is so difficult to map from the new syntax to the  
> old.  There are 10s of thousands of OWL documents out in the world,  
> I'd like to try to figure out the effort to migrate and this would  
> help
>   Could this be done automagically?  Would a "convert to OWL11"  
> program be possible - again, this is because I'm confused for a lot  
> of these predicates as to whether they are necessary or just useful  
> to implementors (but ignorable my many users).
>  Another thing that would help, apparently several of the reasoners  
> (Pellet, Fact+, etc.) now handle OWL11 - do any of the editors?   
> Does Topbraid?  Having a tool we could use to create owl11  
> documents would be helpful for exploring the new language -- I'm  
> teaching an OWL course this term, would love to introduce 1.1, but  
> frankly, I still cannot figure out a lot of it from the documents -  
> the concepts are clear, but not the realization (in the non- 
> technical sense of the word)
>  -JH
> On Oct 23, 2007, at 6:49 AM, Ian Horrocks wrote:
>> The motivation for properties such as subObjectPropertyOf is not  
>> related to punning. The idea is to facilitate parsing/species  
>> validation by enforcing strong typing. For example, it is illegal  
>> in OWL DL for a datatype property to be a subProperty of an object  
>> property, but when parsing a <P subPropertyOf S> triple, the types  
>> of P and S may not be known. As a result, not only will a decision  
>> on the species of the ontology need to be postponed, but it  
>> becomes dependent on a (relatively) complex and non-local  
>> condition, i.e., that P and S are either both datatype properties  
>> or both object properties.
>> Ian
>> On 23 Oct 2007, at 11:22, Jeremy Carroll wrote:
>>> I think Jim's example about subObjectPropertyOf is compelling.
>>> In essence, I don't think we can publish a meaningful and helpful  
>>> RDF Mapping document until we have decided whether or not we  
>>> accept the 'punning' design in the member submission.
>>> I think this is one of the features of OWL 1.1 that causes the  
>>> greatest unease with the HP developers. As I understand the  
>>> design, language terms like subObjectPropertyOf are largely  
>>> motivated by the punning design.
>>> A further possible motivation is that in OWL 1.0, at I think  
>>> mainly my request, one design choice is that the triples version  
>>> of OWL DL is strongly typed, in the sense that (nearly) every URI  
>>> and blank node is required to have an rdf:type triple. Many of  
>>> the required type declarations are unnecessary, and it may be a  
>>> better design to allow unnecessary ones to be omitted. However, I  
>>> think that the explosion of terms in the member of submission is  
>>> unfortuante, and should be avoided.
>>> Jeremy
> "If we knew what we were doing, it wouldn't be called research,  
> would it?." - Albert Einstein
> Prof James Hendler				http://www.cs.rpi.edu/~hendler
> Tetherless World Constellation Chair
> Computer Science Dept
> Rensselaer Polytechnic Institute, Troy NY 12180
Received on Tuesday, 23 October 2007 13:59:21 UTC

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