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Re: Formal Semantics for DAML-S

From: Sheila McIlraith <sam@KSL.Stanford.EDU>
Date: Sat, 1 Jun 2002 12:43:30 -0700 (PDT)
Message-Id: <200206011943.MAA19840@poco.Stanford.EDU>
To: monika@dmu.ac.uk, www-ws@w3.org
Cc: daml-process@bbn.com


Dear Monika,

DAML-S is a DAML+OIL ontology.  As such, the semantics of DAML-S is
well-defined by the semantics of DAML+OIL.  There are 2 papers
describing the semantics of DAML+OIL:  a model-theoretic semantics,
typical of description logics,

http://www.daml.org/2001/03/model-theoretic-semantics

and a so-called "axiomatic" semantics, that provides a set of axioms 
translating DAML+OIL to first-order logic and describing the intended 
interpretation of DAML+OIL in this richer languge.

http://www.ksl.stanford.edu/people/dlm/daml-semantics/abstract-axiomatic-semantics.html

So, the semantics of DAML-S is defined in terms of the semantics of
DAML+OIL.  

Of course there is a "BUT".....

Recall however that DAML-S is comprised of a variety of different ontologies
including a profile ontology, a process model and a grounding.  
The intended interpretation of the profile ontology and the grounding
ontology are well captured by the semantics of DAML+OIL.  

The semantics of the process model is somewhat problematic because DAML+OIL
is not sufficiently expressive to allow us to constrain our process
models to ensure all and only the *intended* interpretation of the
DAML-S process model.  While the interpretation is likely (fairly) clear 
to the reader, from a formal perspective, we need to further constrain the 
ontolgy to ensure that it is accurately defined.  Unfortunately, 
we cannot do so using the language constructs DAML+OIL provides.  E.g.,
three items that are problematic are the representation of state for
the evolution of the system, 2nd order induction for looping constructs,
and constraints that cause the interpretation of DAML+OIL to be cyclic,
such as dataflow constraints between outputs and inputs of composed
processes.
(Recall decidability of DAML+OIL is enforced by ensuring an acyclic
interpretation of the associated graph.)

There have been several pieces of work on defining a semantics for
the process model for DAML-S.  None is complete, but they are
of utility.  Both use the approach of specifying the semantics by
appealing to a richer (more expressive) language.

Recall that the process model appeals to both an "action metaphor"
and a "function metaphor" for services. As such, the various semantic
encodings appeal to different formalisms to elucidate aspects of the
DAML-S process model.  Each has its merits and limitations and the
Coalition is working towards a unified model.

- Narayanan, S. and McIlraith, S., "Simulation, Verification and 
Automated Composition of Web Services", Proceedings of the Eleventh 
International World Wide Web Conference (WWW-11), Honolulu, Hawaii, May, 2002. 
present a model-theoretic semantics for the core of the DAML-S process
model by relating it to the situation calculus, a first-order logical
language for reasoning about action and change.  This has utility in
relating DAML-S to AI-related inference techniques for composition.

This paper also provides a distrubuted operational semantics for DAML-S 
in terms of Petri Nets.

- Anupriya Ankolekar, Frank Huch, Katia Sycara, "Concurrent Execution 
Semantics for DAML-S with Subtypes", to appear in The First International 
Semantic Web Conference (ISWC), June, 2002. 

also presents an execution semantics for the DAML-S process model with
subtypes.  It is similar in spirit to the Petri-Net approach, but with
some interesting differences, as discussed by the authors in the
paper.

I hope this helps.  There is of course, a great deal to say on
this subject and this only touches the surface.

*** all papers refernced above can be found at
   http://www.daml.org/services

Best regards,
Sheila McIlraith

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

Sheila McIlraith, PhD                 Phone: 650-723-7932
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@ksl.stanford.edu
Stanford, CA 94305-9020





	From www-ws-request@w3.org Fri May 31 06:13:57 2002
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	Hi all!!!!!

	I am interested in papers related to formal semantics of the DAML-S 
	language.  Are  there any such documents
	 available?

	Any help appreciated.

	Regards,

	Monika
	-- 
	 >**<>**<>**<>**<>**<>**<>**<>**<>**<>**<
	Monika Solanki
	De Montfort University
	Software Technology Research Laboratory
	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/%7Emonika/>
	 >**<>**<>**<>**<>**<>**<>**<>**<>**<>**<


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	<html>
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	<body>
	Hi all!!!!!<br>
	<br>
	I am interested in papers related to formal semantics of the DAML-S language.
	&nbsp;Are&nbsp; there any such documents<br>
	&nbsp;available?<br>
	<br>
	Any help appreciated.<br>
	<br>
	Regards,<br>
	<br>
	Monika<br>
	<div class="moz-signature">-- <br>
	     &gt;**&lt;&gt;**&lt;&gt;**&lt;&gt;**&lt;&gt;**&lt;&gt;**&lt;&gt;**&lt;&gt;**&lt;&gt;**&lt;&gt;**&lt;
	 <br>
	 Monika Solanki<br>
	 De Montfort University <br>
	 Software Technology Research Laboratory<br>
	   Hawthorn building, H00.18  <br>
	 The Gateway. <br>
	 Leicester LE1 9BH, UK  <br>
	<br>
	    phone: +44 (0)116 250 6170  intern: 6170<br>
	 email: <a href="mailto:monika@dmu.ac.uk">monika@dmu.ac.uk</a>
	<br>
	 web: <a href="http://www.cse.dmu.ac.uk/%7Emonika/">http://www.cse.dmu.ac.uk/~monika/</a>
	<br>
	 &gt;**&lt;&gt;**&lt;&gt;**&lt;&gt;**&lt;&gt;**&lt;&gt;**&lt;&gt;**&lt;&gt;**&lt;&gt;**&lt;&gt;**&lt;
	 <br>
	</div>
	</body>
	</html>

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Received on Saturday, 1 June 2002 15:44:23 GMT

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