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Re: What happens when an ontology has data literals that are outside the range handled

From: Alan Ruttenberg <alanruttenberg@gmail.com>
Date: Thu, 12 Feb 2009 18:10:44 -0800
Message-ID: <29af5e2d0902121810y176eb85br230f6e4f19e9d115@mail.gmail.com>
To: Bijan Parsia <bparsia@cs.manchester.ac.uk>
Cc: W3C OWL Working Group <public-owl-wg@w3.org>

On Thu, Feb 12, 2009 at 3:05 PM, Bijan Parsia
<bparsia@cs.manchester.ac.uk> wrote:
>
> On 12 Feb 2009, at 22:43, Alan Ruttenberg wrote:
>
>> To where can I point Jos to in our spec that defines this behavior?
>
> ? We don't define the behavior I described. We say that implementations must
> support at least 16 digits. If they don't support more we are silent on what
> they should do. I described two possibilities.

This worries me. The problem is that http://www.w3.org/TR/xpath-functions/ says:

For xs:decimal values the number of digits of precision returned by
the numeric operators is ·implementation-defined·. If the number of
digits in the result exceeds the number of digits that the
implementation supports, the result is truncated or rounded in an
·implementation-defined· manner

If our spec allowed that it might be the case that an ontology was
inconsistent in some implementations and consistent in others. If we
don't already disallow this then I think we should. If we do, then I'd
appreciate if someone could point out to me what prevents this.

Regards,
Alan


>
>> The reason I ask is that in some cases the XML docs say operations
>> involving such literals are implementation specific.
>
> Well we don't say what non-conforming implementation should do. If an
> implementation supports on 16 digits that doesn't license it to do what it
> wants with 17 digit numbers. It can, of course, do what it wants, but that
> behavior wouldn't be conforming.
>
>> I contended that
>> that would not be the case for OWL but didn't find a place that said
>> this explicitly.
>
> I don't know that there is. We're nowhere nearly as rigid about conformance
> as I would, ideally, like. But that's probably poltico-socially wise.
>
> I think at the moment the advice I'd give users is that if an implementation
> doesn't do static and dynamic analysis to determine if it's overflowed and
> throw *at least* a warning, that they complain about the implementation
> saying, "You claim to handle only 16 digits, but you really handle more,
> just not in conformance with the spec, loser"
>
> Cheers,
> Bijan.
>
>
Received on Friday, 13 February 2009 02:11:20 GMT

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