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Re: the precondition property in OWL-S 1.0

From: Monika Solanki <monika@dmu.ac.uk>
Date: Sat, 08 Nov 2003 16:10:25 +0000
Message-ID: <3FAD1571.80802@dmu.ac.uk>
To: "Huhns, Michael" <huhns@engr.sc.edu>
Cc: public-sws-ig@w3.org
Hi Michael,

The property that makes it special does not lie in the syntax but in the 
semantics. Precondition is a property which is required to be true, 
before the execution of the service. So there could be several formulae 
that could be classified as Conditions, however if any such formula is 
tagged with a qualifier that it is a precondition, it makes a difference 
in the interpretation of that Condition for the execution of the service.

-Monika

Huhns, Michael wrote:

>Hi Monika,
>
>If a Precondition is a special kind of Condition, then it must have some
>property (or a restriction on some property) that makes it special.
>What is this?  That is, given a logical formula that evaluates to true
>or false, what property does it have that would enable you to determine
>whether it is a Condition or Precondition?
>
>Cheers,
>Mike Huhns
>
>-----Original Message-----
>From: public-sws-ig-request@w3.org [mailto:public-sws-ig-request@w3.org]
>On Behalf Of Monika Solanki
>Sent: Saturday, November 08, 2003 5:15 AM
>To: David Martin
>Cc: public-sws-ig@w3.org
>Subject: Re: the precondition property in OWL-S 1.0
>
>
>
>
>David Martin wrote:
>
>  
>
>>[Note: this thread is moving to public-sws-ig.  After this message,
>>replies should only be sent to public-sws-ig.]
>>
>>Marta Sabou wrote:
>>
>>    
>>
>>> Monika, Drew,
>>>
>>> I completely agree with the proposed solution. This should
>>>definitely be
>>>implemented in the next release.
>>>      
>>>
>>I also agree, except note that there are 2 proposals "on the table":
>>
>>I think Monika suggested this:
>>
>>    Process - hasPrecondition - Precondition
>>where Precondition is a subclass of Condition
>>
>>whereas Drew seems to be suggesting this:
>>
>>    Process - hasPrecondition - Condition
>>
>>(with no Precondition class anywhere).
>>    
>>
>
>I think we should retain the Precondition class and the hasPrecondition 
>property. This is because, although Precondition is effectively a 
>Condition, however it is a "special" kind of Condition. In the process 
>model, Condition is a general thing, which  is also  used for 
>Conditional Effects and Conditional Outputs.
>
>  
>
>>That reminds me - we still have an open issue about the class of an
>>effect (that is, the range of ceEffect).  Currently it's just "Thing",
>>    
>>
>
>  
>
>>which isn't very satisfying. Do people feel that it's OK to have 
>>Condition for this range, or do we need something distinct?
>>
>>- David
>>
>>    
>>
>>> Cheers,
>>>
>>>Marta
>>>
>>>
>>>  Drew McDermott wrote:
>>>
>>>      
>>>
>>>>  [Monika Solanki, in re DAML-S spec]
>>>>  Currently in the 1.0 version of the process model, we have the
>>>>following
>>>>
>>>>    <owl:Class rdf:ID="Precondition" />
>>>>  - <owl:ObjectProperty rdf:ID="preCondition">
>>>>    <rdfs:domain rdf:resource="#Precondition" />
>>>>    <rdfs:range rdf:resource="#Condition" />
>>>>    </owl:ObjectProperty>
>>>>
>>>>  Where, Condition is defined as,
>>>>
>>>>  - <owl:Class rdf:ID="Condition">
>>>>    <rdfs:comment>This is a "place-holder" for now, which awaits
>>>>further
>>>>  work from the DAML/OWL community. An instance of Condition is a 
>>>>logical
>>>>  formula that evaluates to true or false. Eventually we expect this
>>>>        
>>>>
>
>  
>
>>>>to be
>>>>  defined elsewhere, as part of a OWL extension allowing for logical
>>>>  expressions.</rdfs:comment>
>>>>    </owl:Class>
>>>>
>>>>  Somehow I am not able to grasp the utility of the property
>>>>  "preCondition".  Since in this model, we have IOPEs as Classes,
>>>>  therefore I believe all we need to do is make Precondition a
>>>>subclass of
>>>>  Condition.
>>>>
>>>>   <owl:Class rdf:ID="PreCondition">
>>>>    <rdfs:subClassOf rdf:resource="#Condition" />
>>>>    </owl:Class>
>>>>
>>>>  The property preCondition, introduces redundancy as it is ranging
>>>>over
>>>>  the class "Condition" anyways.
>>>>
>>>>  Feedback appreciated in case I missed something.
>>>>
>>>>You're right, as far as I can see.  The important property is 
>>>>hasPrecondition, which connects a Condition to a Process or Process 
>>>>step.  There is no reason for the class Precondition to exist, let 
>>>>alone a property preCondition linking a Precondition to a Condition 
>>>>(itself?).
>>>>
>>>>-- 
>>>>                                            -- Drew McDermott
>>>>                                               Yale University CS 
>>>>Dept.
>>>>        
>>>>
>>>
>>>      
>>>
>
>  
>

-- 
**>><<**>><<**>><<**>><<**>><<**>><<**>><<**
Monika Solanki
Software Technology Research Laboratory(STRL)
De Montfort University
Hawthorn building, H00.18
The Gateway
Leicester LE1 9BH, UK

phone: +44 (0)116 250 6170 intern: 6170
email: monika@dmu.ac.uk
web: http://www.cse.dmu.ac.uk/~monika
**>><<**>><<**>><<**>><<**>><<**>><<**>><<**
Received on Saturday, 8 November 2003 11:06:12 GMT

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