Dan Connolly's tinkering lab notebook

time, context, quoting, and reification

The time and context permathread has heated up again. I used to argue with TimBL endlessly about time context until I read Contexts: A Formalization and Some Applications; from Guha's page at stanford.

A recent post says:

What I’m suggesting is that we build versioning of statements directly into the model. That we make it easy to say:

:article dc:title "I like Cheeses" [-'19-Mar-2006']
:article dc:title “I like Cheese” [’20-Mar-2006′-]

Certainly this is one of the motivations for Notation3 as opposed to turtle. In N3, we write:

{ :article dc:title "I like Cheeses" } holdsDuring '19-Mar-2006'.

The reification design in RDF 1.0 is badly broken. It looks like quoting, but it isn't. It's a huge distraction. I wish the RDF Core WG had had the courage to take it out. I should have pushed harder to take it out; leaving it in obscures the fact that we postponed the quoting issue. The reification stuff that's left in RDF 1.0 is sending a lot of people down a counter-productive path.

Guha's work on context is available in the RDF/OWL work via the cyc time vocabulary. See especially subAbstractions:

...`AlbertEinsteinWhileAtPrinceton' is a #$subAbstractions of `AlbertEinsteinAsAnAdult', which in turn is a #$subAbstractions of 'AlbertEinstein', which in turn is a #$subAbstractions only of itself (hence 'AlbertEinstein' is an instance of #$Entity (q.v.)).

I wrote a message to www-rdf-calendar about cyc subabstractions in April 2003.

I pointed this out in a comment on Ian Davis's recent bio work. It seemed to be news to him.

I did a larch version of my understanding as I read Guha's thesis in 2001. Graham's October 2000 and March 2002 work are a more recent treatment (though I'm less familiar with the latter).

I'm pretty happy with N3 quoting in vocabularies like cyc as a solution to the time context issues.

See also: some slides on web architecture that touch on ist