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Re: A note comparing Conceptual Graphs and RDF/Semantic Web & N3

From: Drew McDermott <drew.mcdermott@yale.edu>
Date: Mon, 15 Jan 2001 11:57:13 -0500 (EST)
Message-Id: <200101151657.LAA02118@mr1.its.yale.edu>
To: Jerome.Euzenat@inrialpes.fr
CC: timbl@w3.org, www-rdf-logic@w3.org

I took a look at Tim's comparison of conceptual graphs and RDF.  The
following puzzles me:

   The concept of "context" occurs very equivalently in CGs and N3, where
   in both cases a formula is built using quotation.
	     In N3, the braces were introduced to encapsulate a set of
   information and talk about it as a set. Using an example from
	     [1], "Tom believes that Mary wants to marry a sailor"

	     [Person: Tom]<-(Expr)<-[Believe]->(Thme)-
		[Proposition:  [Person: Mary *x]<-(Expr)<-[Want]->(Thme)-
		   [Situation:  [?x]<-(Agnt)<-[Marry]->(Thme)->[Sailor] ]].

	     Which in N3 would be (ignoring the type assignments which in
   N3 can be omitted onluess this is really where you want to
	     state that Tom is a person)

	     <#Tom> a :Person; :believes [a :Proposition; = {
		 <#Mary> a :Person; :wants [ a :Situation; = {
		     <#Mary> :marriedTo [ a :Sailor ]
		 ]}
	     ]}.

This is the first I've heard about "quotation" in RDF.  Is this a
synonym for reification, or something else?  If it's a synonym for
reification, then I don't think that's what Sowa intended (although I
am no expert on conceptual graphs).  If it means the ability to
include statements inside statements, then I'd like to know how that
works.  How do we avoid asserting that "Mary wants to marry a sailor"
when we produce the subgraph capturing that meaning?

                                             -- Drew McDermott
Received on Monday, 15 January 2001 11:57:37 GMT

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