However,
one issue remains.
I have seen that these sets can be separated. For example on the page
http://dbpedia.org/ontology/Person/height
I can read that this property belongs to the set of properties from the
improved extraction approach (via rdfs:isDefinedBy
http://dbpedia.org/ontology/).
But when I query the SPARQL endpoint using
SELECT * WHERE {
<http://dbpedia.org/ontology/Person/height> ?p ?o .
}
then I get the following result:
p o
http://www.w3.org/1999/02/22-rdf-syntax-ns#type
http://www.w3.org/2002/07/owl#DatatypeProperty
http://www.w3.org/2000/01/rdf-schema#domain
http://dbpedia.org/ontology/Person
http://www.w3.org/2000/01/rdf-schema#range
http://dbpedia.org/datatype/centimetre
From this information I cannot derive*) to which set the property
belongs to.
Are the datasets the HTML page is generated from and the data that can
be queried via the endpoint different?
*) I know that I could use a regular expression to filter out properties
that do not contain "dbpedia.org/ontology", but I'd prefer using the
rdfs:isDefinedBy property.
Thanks again in advance,
Basil
Am 12.07.2013 17:32, schrieb Basil Ell:
Dear Jona,
thanks a lot for the clarification. I was not aware of the distinction
between these two sets of properties.
Best regards,
Basil
Am 12.07.2013 16:41, schrieb Jona Christopher Sahnwaldt:
http://wiki.dbpedia.org/Datasets#h18-11
Wikipedia infoboxes contain very specific information about things
and are thus a very valuable source of structured information that
can be used to ask expressive queries against Wikipedia. The DBpedia
project currently extracts three different datasets from
the Wikipedia infoboxes.
1. The *Infobox Dataset* is created using our initial, now three
year old infobox parsing approach. This extractor extracts
all properties from all infoboxes and templates within
all Wikipedia articles. Extracted information is represented
using properties in thehttp://dbpedia.org/property/ namespace.
The names of the these properties directly reflect the name
of the Wikipedia infobox property. Property names are not cleaned
or merged. Property types are not part of a subsumption hierarchy
and there is no consistent ontology for the infobox dataset.
Currently, there are approximately 8000 different property types.
The infobox extractor performs only a minimal amount of property
value clean-up, e.g., by converting a value like "June 2009"
to the XML Schema format "2009--06". You should therefore use the
infobox dataset only if your application requires complete
coverage of all Wikipeda properties and you are prepared
to accept relatively noisy data.
2. The *Infobox Ontology*. With the DBpedia 3.2 release,
we introduced a new infobox extraction method which is based
on hand-generated mappings of Wikipedia infoboxes/templates to a
newly created DBpedia ontology
<http://wiki.dbpedia.org/Ontology>. The mappings adjust
weaknesses in the Wikipedia infobox system, like using different
infoboxes for the same type of thing (class) or using different
property names for the same property. Therefore, the instance
data within the infobox ontology is much cleaner and better
structured than the Infobox Dataset, but currently doesn't cover
all infobox types and infobox properties within Wikipedia.
Starting with DBpedia release 3.5, we provide three different
Infobox Ontology data sets:
* The *Ontology Infobox Types* dataset contains the
rdf:types of the instances which have been extracted from
the infoboxes.
* The *Ontology Infobox Properties* dataset contains the actual
data values that have been extracted from infoboxes. The data
values are represented using ontology properties (e.g.,
'volume') that may be applied to different things (e.g.,
the volume of a lake and the volume of a planet). This
restricts the number of different properties to a minimum,
but has the drawback that it is not possible to automatically
infer the class of an entity based on a property.
For instance, an application that discovers an entity
described using the volume property cannot infer that that
the entity is a lake and then for example use a map
to visualize the entity. Properties are represented using
properties following the
http://dbpedia.org/ontology/{propertyname}
<http://dbpedia.org/ontology/%7Bpropertyname%7D> naming
schema. All values are normalized to their respective SI unit.
* The *Ontology Infobox Properties (Specific)* dataset contains
properties which have been specialized for a specific class
using a specific unit. e.g. the property height
is specialized on the class Person using the unit centimetres
instead of metres. Specialized properties follow the
http://dbpedia.org/ontology/{Class}/{property}
<http://dbpedia.org/ontology/%7BClass%7D/%7Bproperty%7D> naming
schema (e.g.http://dbpedia.org/ontology/Person/height).
The properties have a single class as rdfs:domain
and rdfs:range and can therefore be used for classification
reasoning. This makes it easier to express queries against
the data, e.g., finding all lakes whose volume is in
a certain range. Typically, the range of the properties
are not using SI units, but a unit which is more appropriate
in the specific domain.
All three data sets are available for download
<http://wiki.dbpedia.org/Downloads> as well as being available
for queries via the DBpedia SPARQL endpoint.
See also
http://wiki.dbpedia.org/Downloads38#ontology-infobox-properties
http://wiki.dbpedia.org/Downloads38#raw-infobox-properties
On 12 July 2013 12:06, Basil Ell <[email protected]
<mailto:[email protected]>> wrote:
Hi,
I was wondering if there is some dataset that contains
owl:equivalentProperty triples for dbpedia properties.
For example, I believe that the following properties are equivalent:
<http://dbpedia.org/ontology/subsidiary>
<http://dbpedia.org/ontology/subsidiary>
<http://dbpedia.org/property/subsidiary>
<http://dbpedia.org/property/subsidiary>
<http://dbpedia.org/property/subsid>
<http://dbpedia.org/property/subsid>
However, this information cannot be found in dbpedia.
According to
SELECT COUNT DISTINCT * WHERE {
?s owl:equivalentProperty ?o .
}
there are only 31 equivalencies.
When querying the LOD cloud cache at
http://lod.openlinksw.com/sparql,
according to
SELECT count distinct ?s WHERE {
?s owl:equivalentProperty ?o .
FILTER(regex(?s, "dbpedia"))
}
there are 31 triples
and according to
SELECT count distinct ?s WHERE {
?s owl:equivalentProperty ?o .
FILTER(regex(?o, "dbpedia"))
}
there are 87 triples.
From the mappings wiki (http://mappings.dbpedia.org/) I could
extract only 49 equivalencies.
These numbers are rather small. Am I missing something, is there
a data set containing these equivalencies somewhere?
Best regards and thanks for any insights,
Basil
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