RE: about last question

-----Original Message-----
> From: www-rdf-rules-request@w3.org
[mailto:www-rdf-rules-request@w3.org] On Behalf Of Zhu Bin
> Sent: Monday, December 08, 2003 4:57 PM
> To: www-rdf-rules@w3.org
> Subject: about last question
>
>
> The swrl example:
> hasParent(?x1, ?x2)  ?  hasBrother(?x2, ?x3)  =>  hasUncle(?x1, ?x3)
> can I only use OWL to assert these?
>  

Hi Zhu Bin,

You cannot use OWL to express the uncle relationship. OWL is
based on description logics, and it is known that description logics
bear a number of expressiveness restrictions. That is why we need
a rules language.

The following is another example which cannot be captured in
OWL, which is adapted from [1]. According to [1], the following
cannot be described in OWL because "it is impossible to describe
classes whose instances are related to another anonymous individual
via different property paths."

if job:worksFor(?x,?y) and life:livesIn(?x,?z) 
  and geo:locatedIn(?y,?w) and geo:locatedIn(?z,?w)
then
  job:HomeWorker(?x);

Here, job:HomeWorker can only be defined in SWRL or other rules
language.

regards,
Minsu

[1] B. Grosof, I. Horrocks et al. "Description Logic Programms"
(http://www.cs.man.ac.uk/~horrocks/Publications/download/2003/p117-groso
f.pdf)

Received on Monday, 8 December 2003 03:35:18 UTC