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Re: ThisPerform and TheParentPerform special-purpose Perform's instances

From: David Martin <martin@AI.SRI.COM>
Date: Sun, 10 Oct 2004 16:20:40 -0700
Message-ID: <4169C3C8.1050700@ai.sri.com>
To: elena cusenza <elena_cusenza@hotmail.com>
CC: public-sws-ig@w3.org

elena cusenza wrote:

> Hi!
>  I'm using your owl-s 1.1beta definitions ontologies, I think there is a 
> constraint violation on the Perform's instances: ThisPerform and 
> TheParentPerform. (detected using an owl validator)
> Perform definition make a cardinality restriction over "process" 
> property (cardinality=1). Anyway you don't follow this constraint on 
> instances specifications.

It's a valid observation.  We discussed this in the OWl-S Coalition. 
The prevailing view (at least in that discussion) is that it's OK to 
omit the "process" property from the declarations of ThisPerform and 
TheParentPerform.  For one thing, it is still legal OWL.  The 
restriction asserts that each of those instances has a relationship to 
some process, but it does not mandate that the relationship must be 
specified.  This is one of the subtleties of OWL (which some may well 
argue is counter-intuitive).  Hopefully, the validator is reporting this 
as a warning rather than an error.

In any case, there is still room for further discussion about this.

David Martin
Received on Sunday, 10 October 2004 23:21:15 UTC

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