Leigh,
Do you think that http://www.w3.org/2004/03/trix/rdfg-1/ is sufficient
for describing the relationships between graphs (for these purposes)
and if not, what do you think needs adding?
Jeni
On 18 Jan 2010, at 19:20, Leigh Dodds wrote:
Hi Paul,
2010/1/18 Paul Houle <[email protected]>:
For a while I've been struggling with a number of practical
problems working
in RDF. Some of these addressed by Named Graphs as they currently
exists,
but others aren't.
Looks to me like you need Named Graphs plus a mechanism to describe
combinations of graphs.
Over the weekend I had an idea for something that I think is highly
expressive but also can be implemented efficiently.
The idea is that the context of triple can be, not a name, but a
collection of tags that work like tags on delicious, flickr,
etc. Tags
are going to be namespaced like RDF properties, of course, but
they could
have meanings like:
#ImportedFromDBpedia3.3
#StoredInPhysicalPartition7
#ConfidentialSecurityLevel
#NotTrue
#InTheStarTrekUniverse
#UsedInProjectX
#UsedInProjectY
#VerifiedToBeTrue
#HypothesisToBeTested
Individually I call these "Context Tags", and the set of them that
is
associated with a triple is a "Context Set".
I see all of those as being Named Graphs.
Now, named graphs can be composed from boolean combination of
tags, such
as
AND(#ImportedFromDbPedia3.3,#InTheStarTrekUniverse)
NOT(#NotTrue)
AND
(NOT(#ConfidentialSecurityLevel),OR(#UsedInProjectX,#UsedInProjectY))
...and these as more Named Graphs, or at least graphs that are derived
from those in the underlying data store. I tend to refer to these as
"synthetic graphs". Most SPARQL implementations have the concept of at
least one synthetic graph: the union of all Named Graphs in the
system. But as I alluded to in a recent posting [1], there are many
other ways that these graphs could be derived. Rather than building
them into the implementation, they could be described and using a
simple domain specific language. So I think Named Graphs plus graph
algebra gives you much of what you want.
Cheers,
L.
[1]. http://www.ldodds.com/blog/2009/11/managing-rdf-using-named-graphs/
--
Leigh Dodds
Programme Manager, Talis Platform
Talis
[email protected]
http://www.talis.com
--
Jeni Tennison
http://www.jenitennison.com
