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Re: Semantics of Preconditions and Effects

From: Sheila McIlraith <sam@ksl.Stanford.EDU>
Date: Wed, 27 Aug 2003 10:31:27 -0700 (PDT)
To: Monika Solanki <monika@dmu.ac.uk>
Cc: "Sheshagiri, Mithun" <Mithun.Sheshagiri@hp.com>, <daml-process@bbn.com>, www-ws <www-ws@w3.org>, "'steve.battle@hp.com'" <steve.battle@hp.com>
Message-ID: <Pine.GSO.4.44.0308271029060.2938-100000@ksl.Stanford.EDU>





On Wed, 27 Aug 2003, Monika Solanki wrote:

>
> 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.


Watch out.  You can write "Knows(ISBN)" just as you can write
"Foobar(ISBN)" or "Baz(ISBN)", but you need to get the semantics correct
so that "Knows" has the intended interpretation.  Sorry I don' have
more time to respond now.  I'll try to do so later, or perhaps one of
my colleagues will take a shot at carrying on this thread.

- Sheila McIlraith



>
> >
> > 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
> **>><<**>><<**>><<**>><<**>><<**>><<**>><<**
>
>

==============================================================================

Sheila McIlraith, PhD                 Phone: 650-723-7932
Senior Research Scientist             Fax:  650-725-5850
Knowledge Systems Lab
Department of Computer Science
Gates Sciences Building, 2A-248       http://www.ksl.stanford.edu/people/sam
Stanford University                   E-mail: sam-at-ksl-dot-stanford-dot-edu
Stanford, CA 94305-9020
Received on Wednesday, 27 August 2003 13:31:52 GMT

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