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Re: comments on RDF mapping

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Mon, 29 Oct 2007 18:00:08 +0000
Message-ID: <47261FA8.90509@hpl.hp.com>
To: Alan Ruttenberg <alanruttenberg@gmail.com>
CC: Boris Motik <boris.motik@comlab.ox.ac.uk>, public-owl-wg@w3.org

I think the best way to address punning is by stating the requirement 
and looking at whether:

a) this requirement is a requirement, and how widespread
b) whether punning meets this requirement

The only articualtion of the requirement that I am familiar with is:


During the earlier group I felt that it was understood that the 
requirement was not just that you could use the same name for a class as 
for an instance, but that some logical consequences would follow.

for example

This is an OWL 1.0 Full entailment, which (perhaps with minor syntactic 
change) would become an OWL 1.1 DL non-entailment (if I have understood 
punning semantics correctly).

This seems like a divergence away from OWL 1.0 balance between Full and 
DL, and also a divergence away from what I believe the requirement of 
classes as instances is. If two items are the same instance, then they 
are necessarily the same class.

The tests that I think express the punning issue are:

<a> owl:sameAs <b>


<a> owl:equivalentClass <b>


<a> owl:sameAs <b>


<a> owl:equivalentProperty <b>

I currently believe that the member submission OWL 1.1 semantics has 
these both as non-entailments, and that a requirements doc for the use 
case of using an instance URI as a class URI or an instance URI as a 
property URI would have these entailments as holding.

(Obviously it is possible to give a post hoc rationale in which these 
entailments are unimportant - it is easier to tell whether or not a 
design meets a requirement if the requirement is written down, before 
the design is)

Since the OWL 1.0 design solves this problem, in the manner given by

Part of OWL Full.
(and syntactically excluded from OWL DL)

I personally see a variation in which this becomes

"Part of OWL Full; syntactically permitted in OWL DL, but with weaker 

as a backward step


Alan Ruttenberg wrote:
> Hi Jeremy,
> My understanding is that the intention is not to provide a way to get 
> around the univocity of a URI. Rather, some aspects of making that work 
> are not currently known to be decidable, so a compromise is offered  
> insofar as some entailments that would be theoretically desired are 
> skipped, in order to make progress towards a shared goal.
> I wonder whether we can make some fixes to address cases such as the one 
> you point out, particularly when there is no impact on decidability. So 
> perhaps we could consider, in this case, abandoning the distinction 
> between subObjectPropertyOf and subDataPropertyOf so that a subProperty 
> assertion applies to both kinds.
> There will still be an issue with property chains. But I wonder what you 
> think about the general strategy: Making it clear in the documentation 
> that we discourage use of punning to get around univocity, that current 
> behavior that allows this may disappear in future versions of OWL, and 
> patching, to the extent that is feasible without new theoretical work, 
> the current spec in the way that I suggest above.
> As a meta point, could we stay away from statements of the sort : "i.e. 
> punning is an unhelpful idea."? I don't think it is helpful, as there 
> are clearly situations where other people do think it is helpful. Let's 
> instead focus on making things work as best we can.
> -Alan
Received on Monday, 29 October 2007 18:01:02 UTC

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