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Re: [BIONT-DSE] Inclusion versus exclusion criteria

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Thu, 13 Sep 2007 16:44:02 +0100
Message-Id: <2EACA4A0-1917-4653-88B9-2C8623DA8A92@cs.man.ac.uk>
Cc: public-semweb-lifesci hcls <public-semweb-lifesci@w3.org>
To: ogbujic@ccf.org

I trimmed the ccs since I get scared if I have to scroll a cc list.

On 13 Sep 2007, at 15:21, Chimezie Ogbuji wrote:

> On Wed, 2007-09-12 at 14:42 +0100, Xiaoshu Wang wrote:
>> Chimezie Ogbuji wrote:
[snip]
>> But please also see how dangerous such practice will be: "Ian  
>> Horrocks1,
>> Bijan Parsia, Peter Patel-Schneider, and James Hendler, Semantic Web
>> Architecture: Stack or Two Towers"
>> at "http://www.cs.man.ac.uk/~horrocks/Publications/download/2005/ 
>> HPPH05.pdf"
>
> Yes, I'm *very* aware of those two schools of thought :).

Please note that that paper explains that the syntactic intersection  
approach does not yield the same semantics when extended in a variety  
of ways. That is, query languages, for example, can detect the  
difference between a DLP OWL ontology understood in LP vs. the first  
order way.

>   I think the
> domain of discourse is an additional criteria that isn't often
> considered, however.

Eh. Not really. First of all, "domain of discourse" has a couple of  
specific technical meanings so we should be a bit wary about it.

> My quote from [1] was only to ensure we have a
> proper definition of "closed world assumptions" - I often find threads
> on this topic begin with a poor definition and people end up talking
> past each other.

This is a good practice as there are several meanings and CWA doesn't  
really cover all the possible nonmonotonic formalisms and is rather  
biased toward databases.

>   Those two papers address a different (non-trivial)
> question: whether the semantic web stack is best built on top of
> Description Logic or Logic Programming

Well, the two tower's paper doesn't say that. It just says that an  
syntatic intersection doesn't ensure semantic interop, so it's wrong  
to blithely assert that it does.

> (or at least on a framework which
> includes a mapping between the two [1]).
>
> [1]http://www.cs.man.ac.uk/~horrocks/Publications/download/2003/ 
> p117-grosof.pdf

DLP isn't a mapping. For mapping from, e.g., LP to FOL, look at  
things like clark's completion. This cannot be done in the most  
general settings since it would require second order features. But,  
e.g., with nominals, you can restrict the models of an OWL KB in a  
number of ways. One obvious thing you can do is domain closure, i.e.,:

	owl:Thing subClassOf {A, B, C}

where A B and C are individuals and {} is the "oneOf" operator.

Note that DLP-LP and DLP-FOL do coincide for certain classes of  
answer for certain classes of query (since their ground entailments  
coincide).

This has gotten a bit too deeply technical perhaps. From a language/ 
infrastructure design perspective, it seems clear that having some  
sorts of non-monotonic features are quite useful in a number of  
circumstances. For example, having integrity constraints (i.e., some  
sort of data validation) can help with input and cleansing. The  
questions are *which* features (and which variants), how to  
incorporate those features in a usable way, and how to implement them  
in a useful way. The DatabasEsque Features OWLED task force is  
putting together a report on some of this:
	http://code.google.com/p/owl1-1/wiki/DatabasEsque

Cheers,
Bijan.
Received on Thursday, 13 September 2007 15:42:46 UTC

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