Kingsley,
Thanks for pointing out that example of use of the ontology.
This may be a good example to discuss the effects of changing to "type"
relation to "subclass" as it is used for the biological taxonomy. The type
relation appears to be used in the same sense that the rdf:subclasOf is used
in other OWL ontologies. In the usual usage, if X has type Y, then X is an
individual in the class Y, not a subclass. But in the ontology and its
associated applications, to determine the parent classes (at some levels)
one apparently needs to use the "type" rather than subclass relation (i.e.
"Albatross" is usually a subclass, not an instance of "Bird"). It also
appears that the subclass relation is not propagated up the hierarchy, as it
should be for a transitive relation. It is not clear whether these usages
were simply a mistake that has propagated, or a variant definition of these
relations that was intentionally adopted for some reason.
Whatever the reason, I am thinking of the following experiment:
Replace the "type" relation with "subclassOf" in the DBpedia mappings
and ontology where it is appropriate, and add in triples that propagatge the
"subclassOf" up the hierarchy. Then what would happen to the faceted
browsing application? I am guessing that the application assumes that the
"type" relation will be used in the sense of "subclassOf" in the ontology
mappings, and the results would be quite different from what happens now -
and I presume, not what is expected or intended.
If this is the case, then the application would have to be modified to use
"subclassOf" instead of "type", to get the intended results. Would this be
a major effort to make this change?
I start with this suggestion because the unexpected usage of "type" and
"subclassOf" is one of the more striking (to me) examples of how the
ontology appears to be in error. Since the hierarchical "subclassOf"
relation is one of the most important relations in an ontology, I would hope
that that relation be used accurately, before other aspects of the ontology
are modified.
Pat
Patrick Cassidy
MICRA Inc.
cass...@micra.com
908-561-3416
From: Kingsley Idehen [mailto:kide...@openlinksw.com]
Sent: Saturday, December 31, 2011 1:38 PM
To: Patrick Cassidy
Cc: dbpedia-discussion@lists.sourceforge.net
Subject: Re: [Dbpedia-discussion] DBpedia ontology
On 12/30/11 5:14 PM, Patrick Cassidy wrote:
Gerard,
Thanks for the references. I wasn't able to access the Yago-SUMO page.
Perhaps there is another source for it?
I do have the OWL version of the DBpedia ontology, and that is what I have
been looking at as an indicator of the state of the ontology work. I don't
yet know the relation between Yago and the DBpedia ontology. I am not sure
how well mappings would work - in my experience ontologies are so different
that an attempt to use a "same as" link in another ontology would lead to a
lot of incorrect inferences. It could still be quite useful for
probabilistic searches.
I am still in the process of trying to get acquainted with the DBpedia
ontology, and aside from what looks like inconsistencies the structure of
the ontology itself, there is a peculiar usage:
Using the SPARQL query page, types of birds like "Albatross"
(http://dbpedia.org/page/Albatross) are retrieved as instances of "Bird" (
<http://dbpedia.org/ontology/Bird> <http://dbpedia.org/ontology/Bird>), i.e.
the query:
{ ?e <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<http://dbpedia.org/ontology/Bird>}
returns a list of types of birds. I would expect these entries to be
*subclasses* of Bird, rather than *instances* (the usual interpretation of
the rdf:type relation). Is this an intentional variant usage of the
notion of "type"?
There are, in the type list, subtypes of Albatross, such as
"http://dbpedia.org/resource/Wandering_Albatross";. The page says "It was
the first species of albatross to be described" and should therefore be a
subtype of Albatross, but since Albatross is not in the ontology, it is
listed as having type "Bird" or "Eukaryote".
I am aware that on occasion the distinction between an instance and
subclass can be somewhat subtle - for example, for conceptual works, where
there may be more than one version (software!!) it would seem more
appropriate to consider such works as Classes (types) of thing, with the
individual instances being the physical objects that embody the abstract
work. But that is often not the usage. My interest is seeing to what
extent the Dbpedia can be organized so as to be useful for accurate
inference. The ontology at present is sufficiently small that this is
probably quite feasible, if a reorganization does not break some existing
application.
So learning whether there are existing applications that depend on the
current structure of the DBpedia ontology is one of the issues of primary
concern to me in this regard.
Pat
Patrick Cassidy
MICRA Inc.
cass...@micra.com
908-561-3416
Pat,
There is a faceted browser associated with the following data spaces that
hold DBpedia datasets as per these examples:
1.
http://dbpedia-live.openlinksw.com/describe/?url=http%3A%2F%2Fdbpedia.org%2F
resource%2FWandering_Albatross -- DBpedia Live (the variant we host)
2.
http://dbpedia.org/describe/?url=http%3A%2F%2Fdbpedia.org%2Fresource%2FWande
ring_Albatross -- DBpedia Static (periodically updated version of DBpedia
that we host)
3.
http://lod.openlinksw.com/describe/?url=http%3A%2F%2Fdbpedia.org%2Fresource%
2FWandering_Albatross -- DBpedia as part of the Linked Open Data cloud cache
we host.
Using this faceted browser interface enables you to leverage
follow-your-nose exploration patterns across the TBox and the ABox with
powerful effects that include data quality issue discovery, however
subjective they might be :-)
Click the drop-down beside the "start faceted browsing" button for a nice
example.
Kingsley
From: Kingsley Idehen [mailto:kide...@openlinksw.com]
Sent: Friday, December 30, 2011 2:29 PM
To: dbpedia-discussion@lists.sourceforge.net
Subject: Re: [Dbpedia-discussion] DBpedia ontology
On 12/30/11 5:18 AM, Gerard de Melo wrote:
Hi Patrick,
An approach to combine the advantages of both worlds is to interlink DBpedia
with hand-crafted ontologies such as Open Cyc, SUMO, or Word Net, which
enables applications to use the formal knowledge from these ontologies
together with the instance data from DBpedia.
--------------------
I would like to discuss this issue with the person(s) who are creating such
interlinks. Can anyone provide contact information?
The OWL version of SUMO [1] contains some links from SUMO to DBPedia
and YAGO. I originally created those for the YAGO-SUMO project [2], which
aims at an even tighter integration of YAGO and SUMO. The YAGO-SUMO project
had been idle for a while, but I have been working with Adam Pease to get a
new
release out sometime soon, based on the more recent YAGO2 and compatible
with DBpedia.
Best regards,
Gerard
[1] http://www.ontologyportal.org/SUMO.owl
[2] http://www.mpi-inf.mpg.de/~gdemelo/yagosumo.html
<http://www.mpi-inf.mpg.de/%7Egdemelo/yagosumo.html>
--
Gerard de Melo [dem...@icsi.berkeley.edu]
http://www.icsi.berkeley.edu/~demelo/
<http://www.icsi.berkeley.edu/%7Edemelo/>
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Where is the very latest Yago2-SUMO mappings resource?
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Regards,
Kingsley Idehen
Founder & CEO
OpenLink Software
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