RE: Where I am about floats, etc.

Hello,

The problem with unsupported datatypes is that you simply don't know what the intended meaning behind them was. For example, you
have no idea how many objects are then in the interpretation of the datatype, and, as we've seen, this can significantly affect the
consequences. You also don't know how to handle facets, which constants are equal, etc. etc. Any reasoning that one might do with
unsupported datatypes should then be made using conjectures; for example, you might assume that different constants represent indeed
different objects and that the interpretation of the datatype is infinite. (Although I still don't know how to interpret facets.)

Therefore, from a logical point of view, it is much cleaner to say "I don't support it and I can't make any inference about it".

We could weaken this and say that an implementation SHOULD refuse to do anything with an ontology containing unsupported datatypes.
Thus, if some implementation really wants to do this, it can do something by chucking the SHOULD out the window.

Another possibility is for a tool to undertake some repair operation, by translating the unsupported datatype into some supported
datatype and then reasoning with it. I don't think we should specify the details of it, but we might let the tool developers "be
creative".

Regards,

	Boris

> -----Original Message-----
> From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org] On Behalf Of Ivan Herman
> Sent: 07 July 2008 09:43
> To: Boris Motik
> Cc: 'Bijan Parsia'; 'OWL Working Group WG'
> Subject: Re: Where I am about floats, etc.
> 
> 
> 
> Boris Motik wrote:
> > Hello,
> >
> > I would just like to point out that OWL 1 explicitly required support of only strings and integers.
> Therefore, we should be able to
> > not include xsd:float into OWL 2 without breaking backwards compatibility. I'd therefore interpret
> "silent" as meaning "we don't
> > mention it in the list of the supported datatypes".
> >
> > We might want to specify what a tool should do if it encounters a datatype that it doesn't support.
> I believe that the only correct
> > thing to do is to barf -- that is, to inform the user that the ontology contains an unsupported
> datatype and to refuse processing
> > the ontology.
> >
> 
> So we have to be *that* tough? My alternative was that the tool
> processes the ontology with the warning that the datatype related
> inferences might be incorrect...
> 
> Ivan
> 
> > Regards,
> >
> > 	Boris
> >
> >> -----Original Message-----
> >> From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org] On Behalf Of Ivan Herman
> >> Sent: 07 July 2008 08:19
> >> To: Bijan Parsia
> >> Cc: OWL Working Group WG
> >> Subject: Re: Where I am about floats, etc.
> >>
> >>
> >>
> >> Bijan Parsia wrote:
> >>
> >> [skip]
> >>> I think I'm specifically against including xsd:float and xsd:double as
> >>> types at all at this stage, and even as our specing them out as
> >>> optional. (We shouldn't forbid them; just be silent.)
> >>>
> >> I know this is a side issue compared to the main thrust of the
> >> discussion but I would still like to understand what 'non including' and
> >> 'be silent' means in this case. What happens to legacy data?
> >>
> >> My feeling is that being silent is not really possible. We should
> >> specify what happens if a tool gets an ontology/data that is perfectly
> >> o.k. in OWL2 DL or OWL2 EL++ but using, say, xsd:float (or other, non
> >> included XSD datatypes, for that matter): should we rule that the data
> >> is still o.k. in terms of, say, OWL2 EL++ with an additional warning
> >> that the reasoning on datatypes might be shaky, or would that data ruled
> >> to be incorrect and state it it OWL Full? I think something has to be
> >> said in the specification somewhere.
> >>
> >> Personally, I would opt for the former, b.t.w., I suspect that there are
> >> already a bunch of OWL1 DL data out there and we would not want to
> >> refuse them from a DL point of view...
> >>
> >> Bijan, how does Pellet treat such cases? I guess you have met this issue
> >> in practice...
> >>
> >> Cheers
> >>
> >> Ivan
> >>
> >> --
> >>
> >> Ivan Herman, W3C Semantic Web Activity Lead
> >> Home: http://www.w3.org/People/Ivan/
> >> PGP Key: http://www.ivan-herman.net/pgpkey.html
> >> FOAF: http://www.ivan-herman.net/foaf.rdf
> >
> 
> --
> 
> Ivan Herman, W3C Semantic Web Activity Lead
> Home: http://www.w3.org/People/Ivan/
> PGP Key: http://www.ivan-herman.net/pgpkey.html
> FOAF: http://www.ivan-herman.net/foaf.rdf

Received on Monday, 7 July 2008 09:28:40 UTC