W3C home > Mailing lists > Public > www-rdf-logic@w3.org > January 2002

Re: reification

From: Seth Russell <seth@robustai.net>
Date: Mon, 28 Jan 2002 11:03:33 -0800
Message-ID: <00c301c1a82e$7b7aec60$657ba8c0@c1457248a.sttls1.wa.home.com>
To: "Pat Hayes" <phayes@ai.uwf.edu>
Cc: <www-rdf-logic@w3.org>
From: "Pat Hayes" <phayes@ai.uwf.edu>

RE:  http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Jan/0257.html

> >(exists (?x)
> >      (and
> >           (rdf:type ?x  rdf:Statement)
> >           (rdf:predicate ?x :pred)
> >           (rdf:subject ?x :subject)
> >           (rdf:object ?x :obj)
> >))
> >
> >So our interpretation is any of the things which qualify according
> >to the above formula that exist in our universe.
> OK, that's fine. That just treats a reification as a piece of
> ordinary RDF with the standard MT reading. But that means
> that the  reification "of" a piece of RDF now has absolutely no
>connection  with, or particular relationship to, the piece of RDF
> that it is a  reification "of".

I think 'absolutely no connection' is a bit of an over statement; since we
certainly have enough data in the reification syntax to retrieve any triple
that it reified.  This means that there is a mapping from ?r to ?s (call it
k ) which is entirely specified by the syntax;  see my diagram below.  Of
course getting the quantification right on those variables is the job of the
working group.


>That thing that exists is in the semantic universe:
> the piece of RDF that got reified was in the syntax. Nothing
> establishes any kind of connection between them. To get such a
> connection we need to extend the MT in some way.

Ok I can see that.  If ?y and ?x are variables that can quantify over the
set of things that exist corresponding to the triple and it's reification
respectively,  then it seems to me that the job of the working group is to
specify the mappings below and provide some interpretation for them:

i : ?s -> ?y
j : ?r -> ?x
k : ?r -> ?s
l: ?x -> ?y

Informally I would think that the mapping from the reified node to the
triple could be interpreted as naming, representing, or describing.  This
strangely enough has the same interpretation as I would place on the mapping
of a triple to its object in the semantic plain.  Is that interpretation
totally off the wall ?

Seth Russell
Received on Monday, 28 January 2002 14:06:37 UTC

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