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Re: why can't describe the semantic of DAML-S by Description Logic

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Sat, 6 Sep 2003 16:23:14 +0100
Message-ID: <16217.64482.851003.204579@excalibur.oaklands.net>
To: Bijan Parsia <bparsia@isr.umd.edu>
Cc: "lsp" <lsp@is.pku.edu.cn>, <www-ws@w3.org>

On September 2, Bijan Parsia writes:
> On Tuesday, September 2, 2003, at 09:07  AM, lsp wrote:
> > Hi,
> >
> > There have papers describing the semantic of DAML-S using situation
> > calculus, Petri net, operational semantics. But since DAML is naturally
> > described by Description Logic and DAML-S is just ontology for service,
> > why can't we describe DAML-S by DL?
> Good and natural question
> > Any idea?
> Several. First, in so far as we're just after the semantics of our 
> *ontology*, DL may be up to the job (it's not actually clear given some 
> represenational choices which seem to have forced treating some 
> properties as individuals, usually a DL no-no; judicious reworking of 
> the ontology might well avoid this).
> But let's turn to the semantics of the process model alone. It's 
> questionable weather *any* description logic can completely specify the 
> semantics of the process model construct, in their full interaction 
> with preconditions, inputs, outputs, etc. You might look at a prior 
> posting of mine on Processes as Properties (which used the even more 
> impoverished DL OWL DL). The most likely approach would be to use a 
> rather more expressive DL than OWL DL that including various role 
> constructors (or use an extension of a subset of OWL DL). Such logics 
> correspond to Propositional Dynamic Logic and are capable of expressing 
> (and reasoning with) such constructs as if then, repeat, etc. However, 
> the Propositional limitation is a nettlesome one.
> However, I remain ever so slightly charmed by this general approach, 
> and if someone wanted to run further with it, I'd be happy to cheer. A 
> good place to start is to identify a natural and useful class of 
> problems associated with Web services that would naturally be described 
> with PDL.
> Finally, notice that it's somewhat tricky, given the standard DL 
> reasoning services, to get even such obvious wins as matchmaking right. 
> This was brought home to use at the second SWSL F2F by Ian Horrocks (he 
> has a paper explaining the problem) on using subsumption for 
> matchmaking.
> (Of course, this isn't exclusively limited to DLs, in general. KR is 
> tricky :))

It might be interesting to look at work on Abduction in DLs by Donini
et al (WWW2003 [1] and IJCAI2003), and on "non-standard inferences",
e.g., [2].


[1] http://www2003.org/cdrom/papers/refereed/p601/p601-dinoia.html
[2] http://lat.inf.tu-dresden.de/research/papers/2003/BrandtKuesters+LPAR-03.ps.gz

> You might take my Processes as Instances post as a starting point 
> (though I've not put in any references). I started trying to do some 
> funky and (I hope) clever stuff to get around the more obvious 
> limitations. But they rely on various escape clauses  (and perhaps some 
> decidedly non-standard reasoning services) in OWL DL.
> One of our current moves in the DAML-S coalition is to give a 
> (relatively) complete theory of the (or a) process model in full first 
> order logic. Given this, it will be somewhat easier to see how one 
> might map it, or parts of it, to various DLs (though, really, one might 
> argue that there's little sense, practically speaking, in doing so for 
> any DL that's not going to be a (future) extension of OWL; of course, 
> such a process model might provide motive for such; again, it would be 
> good if such a translation were *useful* in some clear way, and thus 
> forming a natural subset).
> Cheers,
> Bijan Parsia.
Received on Saturday, 6 September 2003 09:22:17 UTC

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