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POWDER: my rabbit

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Mon, 17 Dec 2007 16:13:37 +0000
Message-ID: <4766A031.6050109@hpl.hp.com>
To: Phil Archer <parcher@icra.org>
CC: www-archive@w3.org, "Carroll, Jeremy John" <jeremy.carroll@hp.com>, Dan Brickley <danbri@danbri.org>, "Williams, Stuart (HP Labs, Bristol)" <skw@hp.com>, Ivan Herman <ivan@w3.org>, Bijan Parsia <bparsia@cs.man.ac.uk>

Attempting to pull something from my hat ....

How about:

a)

- a POWDER document has a root element, typically wdr:DR, in the POWDER 
namespace.

- a POWDER document is an RDF/XML document

- an RDF/XML document that uses POWDER vocabulary but does not have a 
root element in the POWDER namespace is not a POWDER document

b)

POWDER documents are constrained by some schema (probably not an XML 
Schema) so that they roughly follow the pattern given at

http://www.w3.org/TR/2007/WD-powder-dr-20070925/#structure

or some other similar pattern

c)

A POWDER processor follows an operational semantics, roughly following 
the instructions of the various published WDs

d)

As an RDF/XML document, the formal semantics of a POWDER document is 
arranged to be true, but weaker than the operational semantics.

e)
A GRDDL transform is associated with the POWDER namespace

f)
The GRDDL transform transforms

7      <wdr:ResourceSet>
8        <wdr:includeHosts>example.org</wdr:includeHosts>
9      </wdr:ResourceSet>

into

1  <owl:Class>
2
3    <owl:equivalentClass>
4      <owl:Restriction>
5        <owl:onProperty rdf:resource="&powder;#includeHost" />
6        <owl:hasValue>example.org</owl:hasValue>
7      </owl:Restriction>
8    </owl:equivalentClass>
9  </owl:Class>


etc. (i.e. the GRDDL transform embeds expert knowledge of OWL).

g)
The formal semantics of the GRDDL result of a POWDER document 
corresponds closely to the operational semantics of the POWDER document.

h)
The formal semantics of a POWDER document read by a non-GRDDL aware, 
non-POWDER aware, RDF processor is a proper consequence of the formal 
semantics of a POWDER aware and GRDDL aware reading of the same document.

====

That seems to hit enough of the targets.

Some obvious drawbacks

It continues an overly technocractic semantic web
where there is a two-tier (or even three tier) system of formalism, with 
the 'true' definitions being defined on the 'highest' plane, that is 
accessibly only to an elite with a particular type of 
mathematical/logical background.

There continues to be a divorce between an operational practice, that is 
probably defined in terms of POWDER as XML documents, and actually 
implemented using SAX and DOM like interfaces, and a theoretical model, 
built on semantic web recommendations.

...

Jeremy
Received on Monday, 17 December 2007 16:14:21 GMT

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