Jeremy Carroll wrote:
f)
The GRDDL transform transforms
I thought I should say a bit more about what I had in mind here.
At
http://www.w3.org/TR/2007/WD-powder-dr-20070925/#structure
we find
11 <wdr:hasDescriptors>
12 <wdr:Descriptors>
13 <ex:property1>value 1</ex:property1>
14 <ex:property2>value 2</ex:property2>
15 </wdr:Descriptors>
16 </wdr:hasDescriptors>
Operationally, every resource in the resource set is required to match
this template, i.e. if xxx is the URI of a resource in the resource set.
12 <rdf:Description rdf:about="xxx">
13 <ex:property1>value 1</ex:property1>
14 <ex:property2>value 2</ex:property2>
15 </rdf:Description>
is true.
Formally, without the GRDDL transform, we essentially can just pick one
of the resources in the resource set (which I think should never be
empty), and this then gives a fairly weak formal semantics where
hasDescriptors basically picks out an example from the resource set.
With the GRDDL reading, we turn from an example to a stronger subClassOf
reading, with each of the properties (ex:property1, ex:property2 etc)
being transformed into a hasValue restriction, so that formally, we have
the stronger reading, that every member of the non-empty resource set is
described by the block 12-15 above.
Jeremy
