Sunday, October 17, 2004

FW: Revised draft of CBD 

-----Original Message-----
[]On Behalf Of
Sent: Tuesday, October 12, 2004 2:13 AM

OK. I think I finally have a grasp of what a CBUD is. It's basically
performing the CBD extraction "downwards", so that all object nodes
are either URIrefs, literals, or bnodes not acting as the subject
of any statement in the source graph; and then doing essentially
the same thing "upwards", so that all subject nodes are URIrefs.

Fair enough. And that may arguably be a better definition, and more
useful form, for a SCBD. Or we could define both and differentiate
between them in terms of whether the upward "symmetrical" portion
is partial or full. E.g.

PSCBD "Partially Symmetric CBD" (present def of SCBD)
FSCBD "Fully Symmetric CBD" (CBUD)

Different applications will prefer one over the other. In the
case of a PSCBD, the application is mostly concerned with the
predicate of statements where the objects occur, so 1-level
deep is OK, and bnode subjects for those in-arc statements are
OK. In the case of a FSCBD, the application is interested in
directly related resources, and their descriptions, as well as
the resource denoted by the starting node.

Both of these are likely to be very useful to particular kinds
of applications, and having them defined in a standardized manner
is a good thing.

That said, insofar as the CBD document is concerned, I don't
plan for that to become a clearing house of definitions of
various forms of descriptions -- as it is meant to reflect
what Nokia has found to be particularly useful, not to
speculate about what may also be useful in other application
areas. Even the section defining SCBDs and IFCBDs is hard
to fully justify on those grounds, but I will retain it as
it is useful to illustrate the point that CBDs are not presumed
to be the only useful form of description (even if, possibly,
the most generally useful for the broadest range of applications).

How or where various commonly used forms of description could
be documented and presented as a whole is an open question.

I would love to see either the DA WG or the SW BP WG produce
a non-normative advisory document along those lines, but
something less formal, done as a collaboration of interested
parties, would be good too.




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