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Re: Context Tags, Context Sets and Beyond Named Graphs...

From: Leigh Dodds <leigh.dodds@talis.com>
Date: Mon, 18 Jan 2010 19:20:41 +0000
Message-ID: <f323a4471001181120x7bdb2e79keb842b31fabdd176@mail.gmail.com>
To: Paul Houle <ontology2@gmail.com>
Cc: public-lod <public-lod@w3.org>
Hi Paul,

2010/1/18 Paul Houle <ontology2@gmail.com>:
> 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.



[1]. http://www.ldodds.com/blog/2009/11/managing-rdf-using-named-graphs/

Leigh Dodds
Programme Manager, Talis Platform
Received on Monday, 18 January 2010 19:21:10 UTC

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