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Re: Planning under Description Logic ?--an obstacle towards WSAC

From: Juergen Zimmer <jzimmer@inf.ed.ac.uk>
Date: Thu, 02 Dec 2004 10:57:54 +0000
Message-ID: <41AEF532.6040406@inf.ed.ac.uk>
To: Manshan Lin <lmshill@gmail.com>
CC: public-sws-ig@w3.org

Hi,

this is just my 2 cents...
Manshan Lin wrote:

>hi all,
>I've just read all the discussion about applying AI planning technique to SWS.
>I notice that most traditional planning algorithm are based on first
>order logic, which is based on close-world assumption. And I also
>notice that in order
>to achieve true automatic composition of web service, we must tackle
>the problem of planning under description logic, which is based on
>open-world assumption.
>
>  
>
that is true and Drew has also pointed that out in his paper
" *Estimated Regression Planning for Interactions with Web Services"
*

>The question is :
>When using DL to describe world state, what adaptions should
>traditional AI planning techniques make?
>For example,
>TBOX: EffectA = intersectionOf(EffectB,EffectC)
>ABOX: a individual EffectA
>Then we can choose an operation that achieves EffectA or we can choose
>two operations (one achieves EffectB and the other achieves EffectC).
>It's a little like adding some common rules 
>(in this case EffectB(x) and EffectC(x)->EffectA(x)) 
>to traditional planning domain. When EffectB and EffectC are not
>atomic concepts, the situation becomes more complex. How to handle
>this kind of things in planning algorithms?
>  
>
I've experimented with the (rather old) PRODIGY planner  for SWS 
composition and supposedly it allows to
add axioms like this to planning domain descriptions. Manual at:
 http://www-2.cs.cmu.edu/afs/cs.cmu.edu/project/prodigy/version4.0/pub/manual.ps.gz
So your example would probably along the lines of

(Inference-Rule intersectionClass
 (params <x>)
 (preconds
  ((<x> Effect))
  (and (type <x> EffectB)
          (type <x> EffectC)))
 (effects
  ()
  ((add (type <x> EffectA)))))

Basically, inference-rules are like operators except that they don't 
occur in the final plan.
However, I havn't really worked with this feature so far...
One problem is that Prodigy's type system only allows single inheritance. :(

Personally, I think that planning is not really the right approach to 
SWS composition.

You find many alternative approaches on
   http://staff.um.edu.mt/cabe2/research/projects/swsc/planning.htm
Situation calculus seems appealing but, of course, there is no usable 
implementation
and I don't know much about automation of it...

Cheers
    Juergen

>
>
>
>Best regards!
>			
>Manshan Lin 
>Email: lmshill@hotmail.com;lmshill@gmail.com
>Affiliation: School of Computer Science and Engineering, the South
>China University of Technology
>Phone: (+86)13711287277
>2004-12-02
>  
>
Received on Thursday, 2 December 2004 10:57:58 GMT

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