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

Re: literals and typing

From: Sergey Melnik <melnik@db.stanford.edu>
Date: Mon, 12 Nov 2001 10:07:25 -0800
Message-ID: <3BF00FDD.2243E50B@db.stanford.edu>
To: Geoff Chappell <geoff@sover.net>
CC: Pat Hayes <phayes@ai.uwf.edu>, www-rdf-logic@w3.org
Geoff Chappell wrote:
> 
> > -----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),

right

> 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).

In P(++) it is problematic. However, in S it'd be fine to claim that the
domain of hexint is subClassOf the domain of int (in fact, you could
even claim the equivalence).

> Thanks for clearing that up for me.

You're very welcome,
Sergey

> >
> > Sergey
> >
> 
> Geoff
Received on Monday, 12 November 2001 12:40:27 UTC

This archive was generated by hypermail 2.3.1 : Wednesday, 5 February 2014 07:16:02 UTC