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Re: comment on the fragment document: (inverse) functional and DL-Lite

From: Sandro Hawke <sandro@w3.org>
Date: Thu, 06 Mar 2008 20:59:49 -0500
To: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>, Jim Hendler <hendler@cs.rpi.edu>, Bijan Parsia <bparsia@cs.man.ac.uk>, "Web Ontology Language ((OWL)) Working Group WG" <public-owl-wg@w3.org>
Message-ID: <27418.1204855189@ubuhebe>


> > Actually, the primary idea of DL-Lite is that it has logspace data  
> > complexity, which means that query answering can be implemented using  
> > standard (relational) DB technology. In particular, a conjunctive  
> > query against a DL-Lite ontology can be re-written as an SQL query  
> > against a relational DB containing instance data.
> >
> > Ian
> 
> In what document can/should we say something like that?  I think it's
> very important.  (I realize the first part is in Fragments_Proposal, but
> not the practical/market angle of its relationship to SQL.)

(replying to myself) Arg -- it more-or-less says that later in the
document.  I just missed it, before.  :-(

Still -- maybe in a UCR document? -- it would be nice to have a guide to
the fragments that can be understood by people who wont read sentences
with "LOGSPACE", etc, in them.  That can wait, though, I suppose.

    -- Sandro

>      - Sandro
> 
> 
> > 
> > 
> > On 6 Mar 2008, at 19:23, Jim Hendler wrote:
> > 
> > >
> > > I thought the primary idea of DL-Lite was that it would provide  
> > > primary database functionality -- how can it do that without keys?
> > >
> > >
> > > On Mar 6, 2008, at 6:18 AM, Bijan Parsia wrote:
> > >
> > >>
> > >> On 6 Mar 2008, at 11:04, Ivan Herman wrote:
> > >>
> > >>> Boris, Bernardo,
> > >>>
> > >>> I went through
> > >>>
> > >>> http://www.w3.org/2007/OWL/wiki/Fragments_Proposal
> > >>>
> > >>> again today. One thing that I may have missed: I tried to see if  
> > >>> I can use (inverse)functional properties for DL-Lite or not. I  
> > >>> did not find any reference to those neither in 3.1 nor in 3.2.  
> > >>> Again, I may have missed something...
> > >>
> > >> Let's see if I can discern from the text the situation. (As a test  
> > >> of the spec.)
> > >>
> > >> In section 3:
> > >> 	http://www.w3.org/2007/OWL/wiki/Fragments_Proposal#DL-Lite
> > >>
> > >> 	"""Several variants of DL-Lite have been described in the  
> > >> literature. The variant presented here is called DL-LiteR since it  
> > >> allows for property inclusion axioms; it therefore contains the  
> > >> intersection between RDFS and OWL 1.1 DL. Other variants trade  
> > >> property inclusion axioms for functionality and inverse- 
> > >> functionality of object properties."""
> > >>
> > >> I think this is clear that functionality and inverse functionality  
> > >> of *object* properties are forbidden.
> > >>
> > >> Actually ,the rest of the sections are quiet about data properties  
> > >> altogether. Which would mean that data properties are forbidden in  
> > >> this variant. Which means that it's not really the intersection of  
> > >> RDFS and OWL 1.1 DL?
> > >>
> > >> I do think that if we make this DL Lite not have data properties,  
> > >> the text should call that out (e.g., in the list of missing  
> > >> features). OTOH, I think we should allow data properties ;) I  
> > >> would think it would be ok to trade datasubproperties for keys  
> > >> (from a user pov)...I don't know if that would be ok from the  
> > >> logic/impelmentation pov off the top of my had (while retaining  
> > >> object subproperties).
> > >>
> > >> Cheers,
> > >> Bijan.
> > >>
> > >>
> > >>
> > >
> > > "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 Friday, 7 March 2008 02:01:04 GMT

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