[Freebase-discuss] Dated types
paul at ontology2.com
Thu May 6 14:08:22 UTC 2010
Ed Laurent wrote:
> There have been many(!) discussions about time mediation of just about
> everything over the past few years so there is a general need for
> linking time to topics.
> But, some things to consider ...
> 1) quoting jg on a recent post "we are trying not to be a temporal database".
> 2) lack of data can indicate a lack of data as well as "current" status
> 3) There is often a desire to maintain current data as distinct
> properties for queries, resulting in denormalization.
> I'm personally all for maintaining historical data in Freebase but am
> still puzzled as to how to efficiently do it outside of dated
> properties in personal bases, which make it difficult to combine
> historical data among types.
There are quite a few strategies for this. You can qualify statements,
you can qualify predicates, you can qualify subjects, etc.
Historical modelling gets tough quick. Consider the vernacular entity
"Poland"; the recorded history of this region starts around 966 AD, but
the actual "shape" of Poland has varied drastically since then. At times
it has covered a much wider land area than it has now, but there have
also been times that it hasn't existed at all (as a state.) How do you
represent something like this? One of the principles that I'm chewing on is
A != A
That is, no term is atomic. There's a vernacular conception of "Poland"
but then there are specific "Polish" states that have existed at
different times, such as Polish-Lithuanian Commonwealth, the Jangiellon
dynasty, etc. No database is going to be the 'last word' on reality, but
just a starting place for deeper and deeper explorations of the truth.
If you're going to tackle the issue of time-dependent times, how about
time-dependent names? There's a prison a few miles from my house and it
seems like they change the name on the signs that point to it every year
or so. Fierce battles have been fought, in both the real world and
wikipedia, about a city that Germans call Danzig and Poles call Gdańsk.
Wikipedians ultimately agreed on time-dependent names for the city:
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