@Andra Waagmester: I am a little disconcerted by the property P288 "exact match" <https://www.wikidata.org/wiki/Property:P2888>. I see it is mostly used to link entities, not properties, and I can't figure out how it differs from an external id (unless it's just a convenient way of linking concepts to databases that do not have an external id in Wikidata?)
On Sat, 22 Sep 2018 at 15:55, Peter F. Patel-Schneider < pfpschnei...@gmail.com> wrote: > It is indeed helpful to link the Wikidata ontologies to other ontologies, > particularly ones like the DBpedia ontology and the schema.org ontology. > There are already quite a few links from the Wikidata ontology to several > other ontologies, using the Wikidata equivalent class and property > properties. > Going through and ensuring that every class and property, for example, in > the > DBpedia ontology or the schema.org ontology is the target of a correct (!) > link would be useful. Then, as you indicate, it is not so hard to query > Wikidata using the external ontology or map Wikidata information into > information in the other ontology. > > > The Wikidata ontology is much larger (almost two million classes) and much > more fine grained than most (or maybe even all) other general-purpose > ontologies. This is appealing as one can be much more precise in Wikidata > than in other ontologies. It does make Wikidata harder to use (correctly) > because to represent an entity in Wikidata one has to select among many > more > alternatives. > > This selection is harder than it should be. The Wikidata ontology is not > well > organized. The Wikidata ontology has errors in it. There is not yet a > good > tool for visualizing or exploring the ontology (although there are some > useful > tools such as https://tools.wmflabs.org/bambots/WikidataClasses.php and > http://tools.wmflabs.org/wikidata-todo/tree.html). > > So it is not trivial to set up good mappings from the Wikidata ontology to > other ontologies. When setting up equivalences one has to be careful to > select the Wikidata class or property that is actually equivalent to the > external class or property as opposed to a Wikidata class or property that > just happens to have a similar or the same label. One also has to be > similarly careful when setting up other relationships between the Wikidata > ontology and other ontologies. As well, one has to be careful to select > good > relationships that have well-defined meanings. (Some SKOS relationships > are > particuarly suspect.) I suggest using only strict generalization and > specialization relationships. > > > So I think that an effort to completely and correctly map several external > general-purpose ontologies into the Wikidata ontology would be something > for > the Wikidata community to support. Pick a few good external ontologies and > put the needed effort into adding any missing mappings and checking the > mappings that already exist. Get someone or some group to commit to > keeping > the mapping up to date. Announce the results and show how they are useful. > > > Peter F. Patel-Schneider > Nuance Communications > > > On 9/22/18 4:28 AM, Maarten Dammers wrote: > > Hi everyone, > > > > Last week I presented Wikidata at the Semantics conference in Vienna ( > > https://2018.semantics.cc/ ). One question I asked people was: What is > keeping > > you from using Wikidata? One of the common responses is that it's quite > hard > > to combine Wikidata with the rest of the semantic web. We have our own > private > > ontology that's a bit on an island. Most of our triples are in our own > private > > format and not available in a more generic, more widely use ontology. > > > > Let's pick an example: Claude Lussan. No clue who he is, but my bot > seems to > > have added some links and the item isn't too big. Our URI is > > http://www.wikidata.org/entity/Q2977729 and this is equivalent of > > http://viaf.org/viaf/29578396 and > > http://data.bibliotheken.nl/id/thes/p173983111 . If you look at > > http://www.wikidata.org/entity/Q2977729.rdf this equivalence is > represented as: > > <wdtn:P214 rdf:resource="http://viaf.org/viaf/29578396"/> > > <wdtn:P1006 rdf:resource="http://data.bibliotheken.nl/id/thes/p173983111 > "/> > > > > Also outputting it in a more generic way would probably make using it > easier > > than it is right now. Last discussion about this was at > > https://www.wikidata.org/wiki/Property_talk:P1921 , but no response > since June. > > > > That's one way of linking up, but another way is using equivalent > property ( > > https://www.wikidata.org/wiki/Property:P1628 ) and equivalent class ( > > https://www.wikidata.org/wiki/Property:P1709 ). See for example sex or > gender > > ( https://www.wikidata.org/wiki/Property:P21) how it's mapped to other > > ontologies. This won't produce easier RDF, but some smart downstream > users > > have figured out some SPARQL queries. So linking up our properties and > classes > > to other ontologies will make using our data easier. This is a first > step. > > Maybe it will be used in the future to generate more RDF, maybe not and > we'll > > just document the SPARQL approach properly. > > > > The equivalent property and equivalent class are used, but not that > much. Did > > anyone already try a structured approach with reporting? I'm considering > > parsing popular ontology descriptions and producing reports of what is > linked > > to what so it's easy to make missing links, but I don't want to do > double work > > here. > > > > What ontologies are important because these are used a lot? Some of the > ones I > > came across: > > * https://www.w3.org/2009/08/skos-reference/skos.html > > * http://xmlns.com/foaf/spec/ > > * http://schema.org/ > > * https://creativecommons.org/ns > > * http://dbpedia.org/ontology/ > > * http://vocab.org/open/ > > Any suggestions? > > > > Maarten > > > > > > _______________________________________________ > > Wikidata mailing list > > Wikidata@lists.wikimedia.org > > https://lists.wikimedia.org/mailman/listinfo/wikidata > > _______________________________________________ > Wikidata mailing list > Wikidata@lists.wikimedia.org > https://lists.wikimedia.org/mailman/listinfo/wikidata >
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