[Tagging] Part/whole confusion with Wikidata tag, and the need for enveloping parts into a whole

Yuri Astrakhan yuriastrakhan at gmail.com
Tue Aug 7 13:43:58 UTC 2018

Christoph, you are right that some loosely defined areas like rainforests
may not have exact boundaries. We can find limitations and issues in
defining/naming/linking pretty much anything, e.g. see discussion for
"[Tagging] place nodes for continents". That said, in a large number of
cases, it is beneficial to data consumers to have a 1:1 mapping, e.g. for
examples presented by Peter and Fran├žois.  We do not have to extend that
approach to objects that it won't work well for.

So if it makes sense, it is ok to have a "concept-level" relation that
defines common properties, such as shared wikidata ID, perhaps a relevant
Unesco Heritage ID, a URL, or the hours of operation. It would be a bit
silly to repeat that info on every part of the location.

And for other types of objects, especially the ones without a clear
outline, perhaps it may not make sense to even add wikidata IDs at all.

On Tue, Aug 7, 2018 at 11:04 AM Christoph Hormann <osm at imagico.de> wrote:

> On Monday 06 August 2018, peterkrauss wrote:
> >
> > Seems a commom quality problem of part/whole confusion in the
> > Wikidata attribution or OSM's POI reference... And where there are a
> > need for "enveloping parts into a whole".
> >
> > [...]
> The fact that there is no agreement on the nature of the relationship
> between Wikidata objects and OSM objects has been an important point of
> critique of the whole 'adding wikidata IDs to OSM' movement.  You can
> read this up in the previous discussion here and in talk.
> OSM aims to map based on local verifiability.  Therefore many things we
> map in OSM have no equivalent in Wikidata (because they do not satisfy
> the criteria for inclusion there) and many things in Wikidata cannot be
> mapped verifiably in OSM.  And inventing some kind of collector
> relation that collects all objects that by some wikidata
> interpretation 'belong to' a certain Wikidata ID and thereby implements
> a 1:n relationship would not change that (it would just be pointless
> non-maintainable, non-verifiable dead weight in the database).
> My favourite example for this is the Amazon rainforest (but you can use
> other large eco-regions like the Sahara desert as well).  You won't be
> able to verifiably map the Amazon rain forest in OSM as an entity.
> What we aim to do in OSM is to accurately map the woodlands of South
> America - which is still a very long way to go.  But if this should
> happen it will happen locally because natural=wood/landuse=forest is
> locally verifiable while the abstract concept of naming some of this
> woodland the Amazon rainforest is not.
> --
> Christoph Hormann
> http://www.imagico.de/
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