I can probably think of at least 5 different ways we could arrange the schema of Wikidata to store information about US presidents, but I don't think using universal valid_from and valid_to values for every claim is the most efficient, natural, or flexible way to do so.
> Date: Fri, 5 Apr 2013 00:08:00 +0200
> From: benedix@zedat.fu-berlin.de
> To: wikidata-l@lists.wikimedia.org
> Subject: Re: [Wikidata-l] Page history and properties
>
> And what are you doing when you want the knowledge of the world from 5
> years ago? Isn't this a valid need? To compare what have changed for
> example in the measurement of ocean depth?
>
> These snapshots could be a low hanging fruit with valid_from and
> valid_to and it is saving disk space compared to storing complete dumps
> every day.
>
>
> Instead of having a "List of Presidents of the US" or looking up every
> person for a property "President of the USA" you could get this List
> from the property "President" from the Item "USA" together with
> valid_from and valid_to.
>
> Lukas
>
> Am Do 04.04.2013 22:23, schrieb Michael Hale:
> > I thought one of the main reasons we are making Wikidata is so that
> > you can update a value there, and then everywhere it is used will be
> > automatically updated. If we find a more precise measurement for the
> > depth of an ocean trench, then I just want to update it on Wikidata,
> > and then every article that references it will be updated. I don't
> > want to have to update it on Wikidata and then go do a null edit on
> > every article that uses that information.
>
>
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