Do we loose anything? (discussion on ISSUE-131)

Boris, Zhe,

thanks for the discussion on the OWL-R issue yesterday. I asked the 
question at the meeting on whether we loose anything if we go along 
Boris' proposal[1] and both of you said 'no'. However, I still need some 
extra information to put my mind at ease... Here are two areas where I 
feel some problems may arise (or where I hit the limits of my 
understanding:-). There may be more...

1. Punning

 From an OWL-R-Full point of view, punning is of course not an issue. 
However, the current state of OWL2 is that object/data propery punning 
in DL is _not_ allowed. Doesn't that mean that, if we go along your 
proposal, it would be disallowed in OWL-R (if one wants to bind to the 
official profile) to use the same symbol for data property _and_ object 
property? This may be considered as a major restriction for OWL-R-Full 
users.

2. Reserved vocabulary

One thing we 'formally' loose, of course, is to use the RDF/RDFS 
vocabulary in OWL constructs in OWL-R, too. For 99% of the cases I do 
not really believe anybody in the community would really mind. I do have 
two issues/questions, though, that we might want to look at.

2a. There was a long discussion[2] on what to do with lists, sequences, 
etc. The way I read the discussion is that these construct remain 
disallowed in DL. However, this means that they will stay disallowed in 
OWL-R although the rule set would work perfectly with those being used, 
too. This may be a _major_ loss of functionality for OWL-R-Full users, 
which may be a deal breaker...

2b. The current rule set essentially says that, for example, 
rdfs:subClassOf behaves as a transitive property. However, I am not 
allowed to _declare_ (eg, in a set of axiomatic triples, which also 
relates to issue-116[3], b.t.w.) that rdfs:subClassOf is of type 
owl:TransitiveProperty. Eg, if one does a SPARQL query on the dataset 
after all rules are executed, the query

SELECT ?x WHERE { ?x a owl:TransitiveProperty }

will _not_ return rdfs:subClassOf, although, well, rdfs:subClassOf walks 
like a duck and quacks like a duck...

It is not entirely clear in my mind what an RDF user would expect in 
this case, and we may very well decide that this is not a major issue. 
But we should be clear in our mind that, well, this question may come up!

This is related to all RDFS axiomatic triples plus some extra axiomatic 
triples that might make sense to have in case we have OWL-R-Full (though 
we have not discussed them yet).

Cheers

Ivan

[1] http://www.w3.org/2007/OWL/tracker/issues/131
[2] http://lists.w3.org/Archives/Public/public-owl-wg/2008Jun/0070.html
[3] http://www.w3.org/2007/OWL/tracker/issues/116


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Ivan Herman, W3C Semantic Web Activity Lead
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