- From: Xiaoshu Wang <wangxiao@musc.edu>
- Date: Wed, 12 Sep 2007 14:42:49 +0100
- To: ogbujic@ccf.org
- 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>
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. 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. 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. Think in open world will make the ontology design differently from thinking in closed world. > I think a proper definition of scoped negation as failure would help > show how SPARQL can be used to match the absence of an assertion against > an RDF dataset that can also be subject to open world assumption s at > the same time: > > [[ > 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" Xiaoshu
Received on Wednesday, 12 September 2007 13:44:10 UTC