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Re: [BIONT-DSE] Inclusion versus exclusion criteria

From: Chimezie Ogbuji <ogbujic@ccf.org>
Date: Thu, 13 Sep 2007 10:21:32 -0400
To: wangxiao@musc.edu
cc: public-semweb-lifesci@w3.org, "Alan Ruttenberg" <alanruttenberg@gmail.com>, "Vipul Kashyap" <VKASHYAP1@partners.org>, "Andersson, Bo H" <Bo.H.Andersson@astrazeneca.com>, "Landen Bain" <lbain@topsailtech.com>, "Rachel Richesson" <Rachel.Richesson@epi.usf.edu>, public-hcls-dse@w3.org, "Stanley Huff" <Stan.Huff@intermountainmail.org>, "Yan Heras" <Yan.Heras@intermountainmail.org>, "Oniki, Tom (GE Healthcare, consultant)" <Tom.Oniki@ge.com>, "Joey Coyle" <joey@xcoyle.com>, "Bron W. Kisler" <bkisler@earthlink.net>, "Ida Sim" <sim@medicine.ucsf.edu>
Message-ID: <1189693293.12410.29.camel@otherland>

On Wed, 2007-09-12 at 14:42 +0100, Xiaoshu Wang wrote:
> Chimezie Ogbuji wrote:
> >
> > In SPARQL, the combined use of FILTER/!/BOUND effectively gives you a
> > mechanism for matching records with non-monotonic mechanisms without an
> > entailment regime.  This is how we are able to *explicitly* ask for the
> > absence of an assertion based only on what the RDF dataset has in
> > persistence.
> >   
> A SPARQL endpoint is different from a simple RDF assertion because a 
> SPARQL endpoint answers within the scope of its knowledge base. The 
> context is closed by itself. 

Right, I was demonstrating how RDF assertions can be 'closed' to support
entailment-free query evaluation - as a starting point for certain
non-monotonic mechanisms: scoped negation as failure and scoped
inference.

> But the semantics of an RDF statement is 
> always global and open.  The issue at hand is not if a CWA can or cannot 
> be applied to a given set of RDF statements, it is about if two agents 
> will give consistent answer given the same set of assertions.

Right, but (as demonstrated in "A Realistic Architecture for the
Semantic Web") the inconsistency is not a problem as long as the agent
is aware of the entailment mechanism used.  I don't believe
(theoretically) inconsistent answers is a sufficient justification to
impose an open-world assumption on content that has native
inconsistencies in addition to a clearly-defined scope (this is
*especially* the case with medical records).

> Given a KB "_:someone pha:medicine _:aspirin", you agent can sure 
> interpret that it implies that "_:someone pha:medicin  _:viagra" is 
> false.  But you should not assume that other agent will have the same 
> interpretation. 

You can, if the entailment mechanisms used by the agents are known
apriori.

> > [[
> > Related to the notion of scoped inference is an extension of the concept
> > of default negation, called scoped default negation.  The idea is that
> > the default negation inference rule must also be performed within the
> > scope of an explicitly specified knowledge base. That is, not q is said
> > to be true with respect to a knowledge base K if q is not derivable from
> > K.
> > ]] -- "A Realistic Architecture for the Semantic Web" [1]
> >   
> 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 :).  I think the
domain of discourse is an additional criteria that isn't often
considered, however.  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.  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 (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

-- 
Chimezie Ogbuji
Lead Systems Analyst
Thoracic and Cardiovascular Surgery
Cleveland Clinic Foundation
9500 Euclid Avenue/ W26
Cleveland, Ohio 44195
Office: (216)444-8593
ogbujic@ccf.org


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Received on Thursday, 13 September 2007 14:22:29 UTC

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