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RE: No model theory for reification?

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Thu, 10 Jan 2002 17:08:51 -0000
To: "Dan Brickley" <danbri@w3.org>
Cc: <w3c-rdfcore-wg@w3.org>
Message-ID: <JAEBJCLMIFLKLOJGMELDGEMGCCAA.jjc@hplb.hpl.hp.com>
I think I was advocating a substantially more woolly position than you
appear to want.

A few inline comments follow ...

> saying they're to be used 'for this purpose' (provenance and quoting)
> doesn't adequately describe the meaning of these constructs. What *is* an
> instance of rdf:Statement? We need to give a clear answer, rather than
> allude to possible uses for the class. That's the mistake the old spec
> fell into (cont. below).

Words typically have more than one (related) meaning falling into different
usage patterns. It works in natural language, I have yet to be convinced
that giving (not particularly formal) definitions that follow the
"provenace" model and the "quoting" model is not a solution.

e.g. when discussing the provenance of an RDF statement:

1: A different resource is used for each occurrence of the statment.
2: The resource is of type rdf:Statement
3: The s/p/o properties are as follows: [ omitted ]
4: dc properties are used to describe provenance.
 [I am not suggesting (4) is correct, merely an example]

This sort of resource is referred to as a "stating"

when quoting
Each rdf:Statement resource is uniquely identified by its s/p/o.

This sort of resource is referred to as the Statement.

We observe that each stating as a natural Statement corresponding to it.

While it may seem confusing to have both Statements and Statings represented
in the same way, in practice context will disambiguate.

> How so? Giving a clear definition for rdf:Statement, rdf:predicate,
> rdf:object and rdf:subject might avoid the stating/statement problem.

It is clear to merely say that the rdf:Statement corresponds to the triple
in n-triple and the rdf:subject is the first field, the rdf:predicate is the
second, the rdf:object is the third.

Clarity only vanishes when we claim some deep metaphysical truth about
*identifying* a triple with its reification. If the reification merely
models the triple then it is not difficult.

Received on Thursday, 10 January 2002 12:09:02 UTC

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