Re: [Wikidata] Mapping Wikidata to other ontologies

[David Riccitelli]

Hello Maarten,

We do Semantic SEO so we heavily rely on the schema.org vocabulary. We're
using a SPARQL approach, our input parameter is a DBpedia URI which we use
to retrieve schema.org types and properties using the following properties
chains:

* wdt:P31* (instance of) /wdt:P279* (subclass of) /wdt:P1709* (equivalent
class) to retrieve the schema.org types
* wdt:P1628 (equivalent property) to retrieve the schema.org properties

The result is quite encouraging, e.g. [1]:



[1]
https://search.google.com/structured-data/testing-tool/u/1/#url=https%3A%2F%2Fmagazin.audible.de%2Fhoerbuchtipp-erbarmen%2F%3F1

I hope this helps.

Cheers,
David


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On 22 September 2018 at 13:28, 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:
> http://viaf.org/viaf/29578396"/>
> 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
>
>
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Re: [Wikidata] Mapping Wikidata to other ontologies

[Marco Fossati]

Hi Maarten,

On 9/22/18 13:28, Maarten Dammers wrote:
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.

FYI, I operated the bot that added DBpedia ontology mappings:
https://www.wikidata.org/wiki/User:DBpedia-mapper-bot

I've not been updating the mappings for quite some time, so it would be 
useful to refresh them.

Feel free to ping me if you want to check out the bot implementation.

Cheers,

Marco

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Re: [Wikidata] Mapping Wikidata to other ontologies

[Marielle Volz]

I think probably a distinction can be made in terms of whether your use
case involves exporting items into other ontologies, versus importing items
from other ontologies into wikidata. You'll have different issues with
granularity in either direction and they may not be entirely symmetrical,
so you might actually have to model it in both directions, difficulties of
querying aside.

My use case involves creating wikidata items from citoid
 items, so I have been thinking of
modelling the Zotero/Citation Style Language on wikidata as part of using
citoid on Wikidata (which uses the Zotero ontology.) Unlike schema.org
there's no canonical url pointing to different properties, so I'd actually
like to create an item for each Zotero / Citoid property and actually store
the entire schema itself on wikidata. (This has the additional use case
being able to provide documentation of the properties using reasonator as
well!)

I've created an example on test wikidata here:
https://test.wikidata.org/wiki/Q173241. Here we have the property
publicationTitle, which in citoid/Zotero, has a string value. In wikidata
we would want this to point to an item corresponding to the publication so
we'd use "published in" property as equivalent. There's also hierarchy
modelled here, with websiteTitle being a subclass of publicationTitle:
https://test.wikidata.org/wiki/Q173239

This is a different way of modelling it versus adding an equivalent
property to the wikidata property a la
https://www.wikidata.org/wiki/Property:P356. For my use case, this would be
the easiest model for querying the properties. But I share Stas's concern
here that this could quickly explode the number of items. How many items
called "title" do we need, because "title" is a property in a lot of
examples?

You can see in my example I made my property and instance of both a citoid
property and a zotero property. They mostly overlap, but there are few
citoid properties which are not Zotero properties. CSL properties are even
trickier. I think if they have the same exact name string and all other
properties and equivalencies they can be put in one item but I don't
anticipate that happening much with other less similar ontologies.

Not exactly sure what to use for the name of the property to store the
string, i.e. "publicationTitle" either - might have to create a new
property for that (I checked, Official Name doesn't take "JSON" as a valid
language!)

(The other thing is I've now gone down the rabbit hole of thinking about
modelly markup and programming languages. In a JSON object there's a
limited number of types (Object, string, array, integer etc), and I've had
a go of adding that on test wikidata - but it kind of opens up the idea of
actually adding in a full model of a programming language which sounds
crazy until you consider that we've done basically that with the addition
of lexographical data!)

Cheers,
Marielle

On Sun, Sep 23, 2018 at 8:57 PM Stas Malyshev 
wrote:

> Hi!
>
> > 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
>
> It is technically possible to add values for P1628 into RDF export.
> However, the following questions arise:
>
> 1. Are we ready to claim these are exact equivalents? Sometimes semantic
> meanings differ, and some properties have class requirements - e.g.
> http://schema.org/illustrator expects value to be of class Person, but
> of course Wikidata item would not have that class. Same for the subject
> - it expected to be of a class Book, but won't be. This may confuse some
> systems. Is that ok?
>
> 2. How we deal with multiple ontologies with the same meanings? E.g.
> https://www.wikidata.org/wiki/Property:P21 has 4 equivalent properties.
> There might be more. Do we want to generate them all? Why there are two
> properties for the same FOAF ontology - is that right?
>
> 3. If you change P1628, that does not automatically make all items with
> the relevant predicate update. You need to do an extensive update
> process - which is currently does not exist, and for popular property
> may require significant resources to complete, some properties have
> millions of uses.
>
> Using P1709 is even more tricky since Wikidata ontology (provided we
> call what we have an ontology, which may also not be acceptable to some)
> is rather different from traditional semantic ontologies, and we do not
> really enforce any of the rules with regard to classes, property
> domain/ranges, etc. and have frequent and numerous exceptions to those.
>
> --
> Stas Malyshev
> smalys...@wikimedia.org
>
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Re: [Wikidata] Mapping Wikidata to other ontologies

[Stas Malyshev]

Hi!

> 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

It is technically possible to add values for P1628 into RDF export.
However, the following questions arise:

1. Are we ready to claim these are exact equivalents? Sometimes semantic
meanings differ, and some properties have class requirements - e.g.
http://schema.org/illustrator expects value to be of class Person, but
of course Wikidata item would not have that class. Same for the subject
- it expected to be of a class Book, but won't be. This may confuse some
systems. Is that ok?

2. How we deal with multiple ontologies with the same meanings? E.g.
https://www.wikidata.org/wiki/Property:P21 has 4 equivalent properties.
There might be more. Do we want to generate them all? Why there are two
properties for the same FOAF ontology - is that right?

3. If you change P1628, that does not automatically make all items with
the relevant predicate update. You need to do an extensive update
process - which is currently does not exist, and for popular property
may require significant resources to complete, some properties have
millions of uses.

Using P1709 is even more tricky since Wikidata ontology (provided we
call what we have an ontology, which may also not be acceptable to some)
is rather different from traditional semantic ontologies, and we do not
really enforce any of the rules with regard to classes, property
domain/ranges, etc. and have frequent and numerous exceptions to those.

-- 
Stas Malyshev
smalys...@wikimedia.org

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Re: [Wikidata] Mapping Wikidata to other ontologies

[James Heald]

I would also agree with this.  In my opinion P2888 should only be used 
as a last resort.


If possible, it's usually a much better idea to use a specific 
external-id property for the external database -- it gives us better 
organisation, it's more obvious on the page, and it's much more 
efficient to query.


If you want to emphasise that the matched items are indeed supposed to 
have identical coverage and meaning at each end, use qualifier P4390 
("mapping relation type") with value Q39893449 ("exact match") on the 
external-id statement.


Best regards,

  James.



On 22/09/2018 15:07, Ettore RIZZA wrote:

@Andra Waagmester: I am a little disconcerted by the property P2888 "exact
match" . 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?)



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Re: [Wikidata] Mapping Wikidata to other ontologies

[Peter F. Patel-Schneider]

Hi:

Why did you use exact match (P2888) instead of equivalent class (P1709) and
equivalent property (P1628)?

peter


On 9/22/18 5:07 AM, Andra Waagmeester wrote:
> Hi Maarten,
> 
>     We are actively mapping to other ontologies using the exact match P2888
> property. The disease ontology is one example which is actively
> synchronized in Wikidata using the exact match property (P2888). This property
> is inspired by the SKOS:exact match property. SKOS it self had more mapping
> properties and I think it is a good idea to introduce some of the other SKOS
> mapping properties in Wikidata such broad match and narrow match. 
> 
> Andra
> 
> On Sat, Sep 22, 2018 at 7:30 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:
> http://viaf.org/viaf/29578396"/>
>  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
> 
> 
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Re: [Wikidata] Mapping Wikidata to other ontologies

[Ettore RIZZA]

@Andra Waagmester: I am a little disconcerted by the property P288 "exact
match" . 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:
> > http://viaf.org/viaf/29578396"/>
> > 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
> 

Re: [Wikidata] Mapping Wikidata to other ontologies

[Peter F. Patel-Schneider]

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:
> http://viaf.org/viaf/29578396"/>
> 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
> * 

Re: [Wikidata] Mapping Wikidata to other ontologies

[Iván Hernández Cazorla]

Interesting. I am very interested in this topic. Is there a page on
Wikidata where all this information is collected? One day I read about
the disease ontology mentioned by Andra Waagmeester. But I don't know
where I can track the progress of the mapping, not only to the disease
ontology.

Thanks in advance.

Regards,
Iván

On 9/22/18 1:13 PM, Federico Leva (Nemo) wrote:
> Maarten Dammers, 22/09/2018 14:28:
>> 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/
> 
> Since 2016 there was some progress:
> https://github.com/schemaorg/schemaorg/issues/280
> https://github.com/schemaorg/schemaorg/issues/1186
> 
> The last time I looked into it was for music:
> https://www.wikidata.org/?oldid=297764900#schema.org/MusicRecording
> 
> Mapping properties is tedious but a relatively amount of work (tens of
> hours rather than hundreds) can make a significant difference.
> 
> Federico
> 
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Miembro de Wikimedia España
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Re: [Wikidata] Mapping Wikidata to other ontologies

[Federico Leva (Nemo)]

Maarten Dammers, 22/09/2018 14:28:
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/


Since 2016 there was some progress:
https://github.com/schemaorg/schemaorg/issues/280
https://github.com/schemaorg/schemaorg/issues/1186

The last time I looked into it was for music:
https://www.wikidata.org/?oldid=297764900#schema.org/MusicRecording

Mapping properties is tedious but a relatively amount of work (tens of 
hours rather than hundreds) can make a significant difference.


Federico

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Re: [Wikidata] Mapping Wikidata to other ontologies

[Andra Waagmeester]

Hi Maarten,

We are actively mapping to other ontologies using the exact match P2888
property. The disease ontology is one example which is actively
synchronized in Wikidata using the exact match property (P2888). This
property is inspired by the SKOS:exact match property. SKOS it self had
more mapping properties and I think it is a good idea to introduce some of
the other SKOS mapping properties in Wikidata such broad match and narrow
match.

Andra

On Sat, Sep 22, 2018 at 7:30 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:
> http://viaf.org/viaf/29578396"/>
> 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
>
>
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Re: [Wikidata] Mapping Wikidata to other ontologies

[Ettore RIZZA]

Hi,

I fully agree on the usefulness of this mapping.

Out of 5311 properties, only 232 have equivalents in other schemes

(although
the many external ids are special cases since they are equivalent to some
kind of owl:sameAs.)

If I can help in this job, I'm interested.

Cheers,

Ettore Rizza

On Sat, 22 Sep 2018 at 13:29, 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:
> http://viaf.org/viaf/29578396"/>
> 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
>
>
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