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Re: Semantics of Preconditions and Effects

From: Monika Solanki <monika@dmu.ac.uk>
Date: Wed, 27 Aug 2003 17:56:28 +0100
Message-ID: <3F4CE2BC.3010701@dmu.ac.uk>
To: "Sheshagiri, Mithun" <Mithun.Sheshagiri@hp.com>
Cc: daml-process@bbn.com, www-ws <www-ws@w3.org>, "'steve.battle@hp.com'" <steve.battle@hp.com>

Sheshagiri, Mithun wrote:

> 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.

This is precisely what I was aiming at.

>  
> 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.
>  

I don't think so it is correct to deduce anything
(a) if it is not specifiied explicitly in the output
(b) if it is not specified anywhere in the service ontology specification

As Sheila mentioned in one of the other emails that it may be possible 
that a provider may not want to divulge the details abt loan denial. In 
such a scenario, no deductions can be made.

> Alternatively if the semantics is only an implication,

I think it should be, atleast logically it makes sense.

> 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")

I think we do need to specify something like this

> 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 
>  

This can be discussed further as Bijan has suggested in one of the other 
emails

> 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.

Since nothing is mandatory in the specification currently, I guess it 
all depends on the service provider, i.e. if he wants to send it as part 
of the output

> mithun

> http://www.cs.umbc.edu/~mits1 <http://www.cs.umbc.edu/%7Emits1>
>  

Any comments from other members appreciated

Cheers,

Monika

> -----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
>     -- 
>     **>><<**>><<**>><<**>><<**>><<**>><<**>><<**
>     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
>     **>><<**>><<**>><<**>><<**>><<**>><<**>><<**
>

-- 
**>><<**>><<**>><<**>><<**>><<**>><<**>><<**
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 Wednesday, 27 August 2003 12:58:09 GMT

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