RE: Effects in OWL-S

Here's another way of thinking about this - essentially from the situation
calculus. An effect describes things that are true _because_ of an action,
whereas, a postcondition describes things that are true _following_ an
action.

Not everything that is true following an action is true because of it. A
small example : If I add item A to my shopping trolley, then the effect is
that "item A is in my trolley". If I then add item B to my trolley, then the
effect is that "item B is in my trolley". Now, it's reasonable to assume
that "item A is in my trolley" remains true because nothing I've done claims
to effect the truth of it. So given that "item A is in my trolley" is a
precondition of the "add item to trolley" action then "item A is in my
trolley" is a reasonable post-condition, but not an effect. A lot of good
work has gone into working out what post-conditions are reasonable given the
effects (see the 'frame problem').

Steve

> -----Original Message-----
> From: public-sws-ig-request@w3.org
> [mailto:public-sws-ig-request@w3.org]On Behalf Of Charlie Abela
> Sent: Wednesday, April 14, 2004 6:26 PM
> To: Public-Sws-Ig@W3. Org
> Subject: Re: Effects in OWL-S
> 
> 
> 
> With all these ideas going on about preconditions and effects 
> in OWL-S it is
> quite difficult to capture the general idea of how to define 
> actual effects
> in WSs.
> 
> I had the impression that an effect was something that will 
> become true when
> the WS has executed but that also brought some changes to the 
> world, but now
> there is talk of making use of post-condition instead. 
> Actually from the
> readings that I found, these two words seem to be used 
> interchangeably,
> depending on the research context, and thus I always presumed 
> that they are
> somewhat synonymous.
> 
> What are the views of the OWL-S ppl on this? Cause with all 
> these somewhat
> radical changes being proposed it is quite difficult to get people to
> actually make use of these ontologies. Will there every be a 
> stable set of
> OWL-S ontologies?
> 
> Some time back there was a long discussion on the topic; I guess some
> clarification is now due.
> 
> Regards
> 
> Charlie
> 
> 
> 
> 
> 
> 
>

Received on Monday, 26 April 2004 10:44:19 UTC