Hi Michael,
regarding the redirects, it would really be a lot of work to code
something that distinguishes them into owl:sameAs and rdfs:seeAlso.
That said, I am sure that somebody already did this, see e.g. here:
https://scholar.google.de/scholar?hl=en&as_sdt=0%2C5&q=wikipedia+redirects&btnG=
maybe this one: Analyzing and accessing Wikipedia as a lexical semantic
resource
At the moment we are facing two major challenges, which will hopefully
be fixed in the next weeks:
1. it is hard to contribute to DBpedia: we are developing a client to
push external efforts to DBpedia via the DBpedia Databus, see here:
https://github.com/dbpedia/data-release-tool-ti/blob/master/README.md
So in the future, anybody who creates such an extension or a let's call
it a fork of the "DBpedia redirects" dataset can push it again. Ideally,
we release metadata about the releases and others can scan for new data
and then run their tools automatically and re-publish results. We
recently had a call for first people to help us test the release client:
https://sourceforge.net/p/dbpedia/mailman/message/36375367/
2. URIs from Wikipedia are not stable in the first place. Not sure about
the percentage, but let's say 5% of the uris get changed and redirected
each year
We have created new URIs that are stable. Alex Olieman has already
created a service to map them:
https://e.hum.uva.nl/same-thing/lookup/?uri=http://www.wikidata.org/entity/Q8087
But you can see that the service is also not using the redirects for the
reasons stated by Nicolas:
https://e.hum.uva.nl/same-thing/lookup/?uri=http://dbpedia.org/resource/Brown_pelican
https://e.hum.uva.nl/same-thing/lookup/?uri=http://dbpedia.org/resource/Brown_Pelican
Some notes about the service:
- the global ids will be
http://global.dbpedia.org/id/${base58endodedBigInt} we had a conflict
with id.dbpedia.org
- the ids are generated by enumerating all uris af the sources with
bigints and then merge them into clusters based on owl:sameAs
While this works great per se, we still need a better control over the
owl:sameAs links that go into the merge. But the effect is that the IDs
are stable.
As you are updating at the moment, I would suggest that you store the
new ids alongside in your app, which will make further updates much easier.
In general, the data fused in the new releases will be much richer as
they combine data from all wikipedias and wikidata into one space.
All the best,
Sebastian
On 31.07.2018 09:30, Michael Brunnbauer wrote:
Hello Nicolas,
sorry I cannot follow your example. The Terminator6 URI does not seem to
reference anything on DBpedia:
http://dbpedia.org/resource/Terminator6
Did it reference something in some earlier version? Not in mine from 2012.
Regards,
Michael Brunnbauer
On Fri, Jul 27, 2018 at 03:19:08PM -0700, Nicolas Torzec wrote:
I'll let the DBpedia folks reply but identity management is a hard problem.
Example:
- On one hand Brown_Pelican
<https://en.wikipedia.org/w/index.php?title=Brown_Pelican&redirect=no>
redirects to Brown_pelican <https://en.wikipedia.org/wiki/Brown_pelican>
and they happen to reference the same entity.
- On the other hand, Terminator 6
<https://en.wikipedia.org/w/index.php?title=Terminator6&redirect=no>
redirects to the Terminator franchise
<https://en.wikipedia.org/wiki/Terminator_(franchise)> and yet they
reference different entities.
- So an owl:sameAs <https://www.w3.org/TR/owl-ref/#sameAs-def> may be
appropriate in the first case but not the second one.
Cheers.
-N.
On Fri, Jul 27, 2018 at 10:20 AM Michael Brunnbauer <bru...@netestate.de>
wrote:
hi all,
we are planning to upgrade the DBpedia version used for our app from 3.8
(2012) to the current version.
It seems that when a Wikipedia entry changes its URL, so does the
corresponding Dbpedia URI. This is of course a no go and I don't know why
the team decided not to keep the old URI in that case but I'm sure there
were good reasons.
So the currently used DBpedia version 3.8 has both
http://dbpedia.org/resource/Brown_Pelican
http://dbpedia.org/resource/Brown_pelican
with no triples connecting each other. The users of the app I am
maintaining have used the Brown_Pelican URI which seems to be the older one.
The current DBpedia has made Brown_pelican canonical and has the following
to say about the old URI:
http://dbpedia.org/sparql?default-graph-uri=http%3A%2F%2Fdbpedia.org&query=select+%3Fp+%3Fo+where+%7B%0D%0A%3Chttp%3A%2F%2Fdbpedia.org%2Fresource%2FBrown_Pelican%3E+%3Fp+%3Fo%0D%0A%7D&format=text%2Fhtml&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000&debug=on&run=+Run+Query+
There is no owl:sameAs link but a dbo:wikiPageRedirects from the old to
the new URI.
Why is there no owl:sameAs triple generated for every
dbo:wikiPageRedirects?
What possible problems could arise if our app treats dbo:wikiPageRedirects
like a owl:sameAs assertion?
Is it possible that URIs changed without a corresponding
dbo:wikiPageRedirects triple documenting the change?
Regards,
Michael Brunnbauer
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All the best,
Sebastian Hellmann
Director of Knowledge Integration and Linked Data Technologies (KILT)
Competence Center
at the Institute for Applied Informatics (InfAI) at Leipzig University
Executive Director of the DBpedia Association
Projects: http://dbpedia.org, http://nlp2rdf.org,
http://linguistics.okfn.org, https://www.w3.org/community/ld4lt
<http://www.w3.org/community/ld4lt>
Homepage: http://aksw.org/SebastianHellmann
Research Group: http://aksw.org
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