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Re: the precondition property in OWL-S 1.0

From: Austin Tate <a.tate@ed.ac.uk>
Date: Sun, 09 Nov 2003 11:42:10 +0000
Message-Id: <>
To: public-sws-ig@w3.org

At 10:09 AM 09/11/2003 +0000, Monika Solanki wrote:
>Well, my only interest here was to keep all the concepts used in defining 
>"a" process explicit. Normally, the "Precondition" does not give us 
>anything more than what "Condition" does and the "hasPrecondition" 
>property expresses the relation it has with the process. I am not rigid 
>about having  the Precondition class, just for the sake of having it... 
>:-)   .. But I guess a few more opinions on this would not harm. The only 
>problem I had was the "precondition" property , that we currently have in 
>the model

Note my comment below is for the SWSL process model really and not just for 
tidying up OWL-S as its too radical a step. But it might be something that 
could guide any changes in OWL-S to...

I am not keen on adding lots of separate properties to activity... where do 
you stop... do you add resource, spatial, authority, temporal constraints 
(some people even try to maintain successor and predecessors lists in each 
process step!).

I would favour a much simpler underlying idea that an activity always ha

a) an (implicitly) associated begin and end time point

b) can optionally can be broken down into 0 or more sub-activities - if 0 
its considered as a primitive activity in the current model)

c) a set of constraints of various types on and between the activity, the 
objects manipulated by that activity and the time-points of the activity 
and any of its sub-activities.  The constraints then include the simplest 
activity ordering constraint "(before end-of(activity-1) to 
begin-of(activity-2))" and world state preconditions/effects as 
specialisations that are frequently used - but they are not the only ones.

Then we can avoid the syndrome of 25 properties on activity - growing to 75 
properties as more requirements emerge.

Received on Sunday, 9 November 2003 06:43:09 UTC

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