W3C home > Mailing lists > Public > www-webont-wg@w3.org > May 2002

Re: ISSUE: Malformed DAML+OIL Restrictions

From: patrick hayes <phayes@ai.uwf.edu>
Date: Sat, 18 May 2002 21:44:05 -0500
Message-Id: <a0511171eb90ca1ef703f@[]>
To: Jim Hendler <hendler@cs.umd.edu>
Cc: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>, www-webont-wg@w3.org
>At 2:35 PM -0400 5/16/02, Peter F. Patel-Schneider wrote:
>>TITLE:       Malformed DAML+OIL Restrictions
>>DESCRIPTION: DAML+OIL allows for restrictions that are malformed.
>>	     Restrictions with missing components (e.g., a
>>	     restriction with no daml:onProperty triple) have no
>>	     semantic impact, even though treating them as RDF would
>>	     indicate that there should be some semantic import. 
>>	     Restrictions with extra components (e.g., a restriction 
>>	     daml:onProperty triples to more than one property) have
>>	     unusual and misleading semantic impact (in general equating
>>	     the extensions of two or more well-formed restrictions).
>>	     Both of these should be syntactically illegal in OWL.
>>RAISED BY:   Peter F. Patel-Schneider
>Peter - issues shouldn't include solutions (i.e.  that these should 
>be syntactically illegal in OWL) - maybe "Perhaps both of these 
>should..." would be better wording?
>Also, please explain what you mean by syntactically illegal?  My 
>understanding is that we decided we would use RDF/XML as the 
>exchange language, and triples graphs to convey meaning, so how 
>would you keep these from being syntactically expressible? 
>Semantically illegal I understand, syntactically I don't understand

Oh, come. We have decided to use RDF/XML as the exchange language, 
but that does not require us to say that any piece of syntactically 
legal RDF/XML is also syntactically legal OWL. In fact, we cannot 
possibly say that, nor should we want to. OWL will of necessity 
impose its own extra wellformedness conditions on RDF/XML, just as 
DAML does.

Peter is correct that these should be syntactically illegal. What 
that means is that  an OWL parser should reject them as ill-formed on 
syntactic grounds. The issue, as I understand it, is HOW to make them 
syntactically illegal, ie how to state the OWL syntactic rules 
properly so as to rule out such things.

Received on Monday, 20 May 2002 10:54:55 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 23:04:30 UTC