W3C home > Mailing lists > Public > www-rdf-logic@w3.org > November 2001

RE: literals and typing

From: Geoff Chappell <geoff@sover.net>
Date: Sat, 10 Nov 2001 06:52:42 -0500
To: "Sergey Melnik" <melnik@db.stanford.edu>
Cc: "Pat Hayes" <phayes@ai.uwf.edu>, <www-rdf-logic@w3.org>
Message-ID: <NFBBJNGEILIMIEFCFDIIMEOACAAA.geoff@sover.net>


> -----Original Message-----
> From: Sergey Melnik [mailto:melnik@db.stanford.edu]
> Sent: Friday, November 09, 2001 10:22 PM
> To: Geoff Chappell
> Cc: Pat Hayes; www-rdf-logic@w3.org
> Subject: Re: literals and typing
>
>
> > If I understand the delicacy issue with P/P++ it's that a class
> and one of
> > its subclasses might have different lexical domains (e.g.
> hexint, int) and
> > so it will be unclear/ambiguous in which form the literal value
> is actually
> > encoded as a string. But doesn't the same issue exist with S?
> if we have:
> > (#whoknows hexint "70") and (hexint subPropertyOf int) we can infer
> > (#whoknows int "70"). Can't these problems exist in any of the schemes
> > except X (and only not there because types aren't exposed to inference -
> > i.e. there are no datatypes visible to RDF).
>
> In S, asserting (hexint subPropertyOf int) yields an empty
> interpretation (in other words, this assertion is inconsistent with the
> definition of hexint and int). You wouldn't want to assert things like
> that...

Yes, I see. That's why you use a relation rather than membership in a class
to specify datatype -- because it captures the intended binding of a string
to a value. It's just plain wrong to claim that hexint is a subPropertyOf
int (unless your world consists of 0-9 only), whereas it's just a bad idea
to claim that hexint is a subClassOf int (it's valid in that the members are
the same, but ambiguous from the perspective of mapping string
representations to values).

Thanks for clearing that up for me.

>
> Sergey
>

Geoff
Received on Saturday, 10 November 2001 08:29:06 UTC

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