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Re: Representation of SWRL expressions in OWL-S

From: Bijan Parsia <bparsia@isr.umd.edu>
Date: Fri, 4 Feb 2005 09:21:39 -0500
Message-Id: <15CFEFA4-76B8-11D9-9806-000D93C1F7A6@isr.umd.edu>
Cc: "daml-process@bbn.com" <daml-process@bbn.com>, Daniel Elenius <elenius@csl.sri.com>, public-sws-ig@w3.org
To: Evren Sirin <evren@cs.umd.edu>

On Feb 4, 2005, at 1:35 AM, Evren Sirin wrote:

> Daniel Elenius wrote:
> I have two concerns about this format:
>> 1) Aren't all SWRL expressions supposed to be instances of the 
>> http://www.daml.org/rules/proposal/swrl.owl#Imp class?
> No, a SWRL expression body is supposed to be an AtomList which is 
> simply the conjunction of atoms in the list.

By design.

>> I know that this was the case in an intermediate
>> version of OWL-S, but this version does not seem to be available 
>> anymore. Expressions were rules with
>> empty heads (bodies?).
> I think at some point it was considered to use rules with empty 
> bodies. Then the expression would be written as the head of the rule. 
> SWRL defines empty body to be trivially true so the implication is 
> true whenever the head is true. But using rules in this way would be 
> more confusing so it was decided to use AtomList's directly.

It's not just confusing, it's the wrong semantics, right? Precondtions 
*aren't* always true!

>> 2) If this is not the case, i.e. we can use constructs from SWRL as 
>> we feel like it,
> No, we can not.

Definitely not. The intention was that you'd use SWRL constructs in the 
relevant *ontologies*. So *outside* and expression, you can use SWRL 
rules as you see fit.

Received on Friday, 4 February 2005 14:22:57 UTC

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