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RE: Semantics of Preconditions and Effects

From: Sheshagiri, Mithun <Mithun.Sheshagiri@hp.com>
Date: Wed, 27 Aug 2003 16:49:00 +0100
Message-ID: <5E13A1874524D411A876006008CD059F073836FC@0-mail-1.hpl.hp.com>
To: "'Monika Solanki'" <monika@dmu.ac.uk>, daml-process@bbn.com, www-ws <www-ws@w3.org>
Cc: "'steve.battle@hp.com'" <steve.battle@hp.com>
Since ceEffect points to owl:Thing, there is nothing that prevents you from
representing Knows(ISBN) as an effect. Also, it is useful to have a means by
which you can generate an effect which is also a precondition for some other
service.
 
I also had some doubts about the semantics of conditional O/Es.
 
Loan Service:
   1. output = "loan approved", if creditRating = good
   2. output = "loan denied", if creditRating = poor
 
If this were the advertised service and after execution of the service using
WSDL, I get my output as "loan denied". It is important to know the value of
CreditRating, since it could be used to determine the cause of  the
output:"loan denied" and a contingency plan can be worked out. There are 2
ways of finding the value of creditRating: make it part of the output
message or deduce it from the output.
At per current spec, the value of creditRating is not part of the WSDL
grounding (output message). Is it correct to deduce that my creditRating is
"poor" from the output "loan denied"? If this deduction is correct, then the
semantics is IFF.
 
Alternatively if the semantics is only an implication, is the following
correct:
As part of the service description I make the following additional
statements:
3. output of Loan Service is disjointUnionOf  ("loan approved" and "loan
denied")
4. "loan approved" owl:complementOf "loan denied"
5. So when I get the output "loan denied" can I say something like
output(loan denied) is equivalent to ¬output(loan approved)
6. From 1. (and assuming ¬good=poor), I have creditRating=poor 
 
And if value of creditRating cannot be found by any means (explicit,
deduction or some other service), then is there a need for using
creditRating in describing th service? This problem could be solved by
sending the value of creditRating as part of the output.
 
mithun
http://www.cs.umbc.edu/~mits1 <http://www.cs.umbc.edu/~mits1> 
 
-----Original Message-----
From: Monika Solanki [mailto:monika@dmu.ac.uk] 
Sent: Wednesday, August 27, 2003 2:26 PM
To: daml-process@bbn.com; www-ws
Subject: Semantics of Preconditions and Effects



Hi All,

I am trying to understand the semantics of preconditions and effects . In
one of the papers 

Narayanan, S. and McIlraith, S., "Simulation, Verification and Automated
Composition of Web Services", 

I found that preconditions for any service can also be modelled as knowledge
based apart from physical preconditions.For e.g: agent Knows(bookName) for a
service like LocateBook. I am interested in knowing whether agent can have
knowledge based effects as well for e.g: agent Knows(ISBN), especially for
information providing services.

Any thoughts appreciated.
  
Cheers,

Monika

-- 
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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 <mailto:monika@dmu.ac.uk>  
web: http://www.cse.dmu.ac.uk/~monika <http://www.cse.dmu.ac.uk/~monika> 
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Received on Wednesday, 27 August 2003 12:15:19 GMT

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