- From: David Booth <david@dbooth.org>
- Date: Mon, 28 Sep 2009 13:55:47 -0400
- To: paoladimaio10@googlemail.com, Paola Di Maio <paola.dimaio@gmail.com>
- Cc: Pat Hayes <phayes@ihmc.us>, semantic-web at W3C <semantic-web@w3c.org>
On Mon, 2009-09-28 at 12:10 -0500, Pat Hayes wrote:
. . .
> In RDF, domains and ranges belong to properties (the things in the
> middle of the triples). The idea is that if the domain of P is D and
> the range of P is R, then when you write a triple
>
> a P b .
>
> then you are implying that a is in D and b is in R. Obviously D and R
> have to be classes. For example, the domain and range of motherOf
> might be respectively Woman and Human, so that if I write
>
> Betty motherOf Pat .
>
> you can infer that Pat is human and Betty is a woman.
Furthermore, it is perfectly legal to declare the domain of a property
more than once, such as:
P rdfs:domain GreenItems .
P rdfs:domain BlueItems .
Then if you write a statement like:
x P y .
the domain declarations imply that x is in both GreenItems and
BlueItems. Note that the effect is that the domain of P is the
*intersection* of GreenItems and BlueItems -- not the union.
--
David Booth, Ph.D.
Cleveland Clinic (contractor)
Opinions expressed herein are those of the author and do not necessarily
reflect those of Cleveland Clinic.
Received on Monday, 28 September 2009 17:56:24 UTC