---------------------
On 12/31/11 5:34 PM, Patrick Cassidy wrote:
[pc] 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.
[KH] Transitivity kicks in when you enable inference context. This is simply
off by default. There are a number of ontologies that also serve as
inference rules. Enable those, and you will see what you expect. The cost of
these operations is why we turn them off by default.
----------------
Is this inference enabled in the extraction from infoboxes to the DBpedia
triple store? Or is there a way to enable transitiity during the SPARQL
query process?
The other issue is why, in relating the WikiPedia pages to the ontology,
"type" is used to relate, e.g. "http://dbpedia.org/page/Albatross"; to
"Bird", rather than "subcassOf". The heading of that page has:
About: Albatross <http://dbpedia.org/resource/Albatross>
An Entity of Type : eukaryote <http://dbpedia.org/ontology/Eukaryote> , from
Named Graph : http://dbpedia.org, within Data Space : dbpedia.org
It is this usage of "Type" that I find problematic. Is there a reason for
this - is it not intended to mean the same thing as rdf:type?
It appears at first glance as if this were adopted as a means to keep the
ontology small (so Albatross does not have to be added as a class to the
ontology) - is that part of the motivation?
Pat
Patrick Cassidy
MICRA Inc.
cass...@micra.com
908-561-3416
From: Kingsley Idehen [mailto:kide...@openlinksw.com]
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