Hello, Piero Molino schrieb: > Hi Jens, > [...] > > This remembers me of leacock chodorow measure used in my research lab > for calculating semantic distance in wordnet. The fact that there's a > class wich is a kind of root is a good thing for this. There's something > alse like that i should know? Or can you even suggest me something like > a tool for visualizing the ontology and became aware of his > characteristics? (in a university course we used protege for building > example ontologies, could it be useful?)
Yes, Protégé can be useful. If you open the DBpedia ontology in Protege, go to the OWLViz tab, then select "Options" => "Radius 5", you get an overview of all classes. >> Google comes up with a >> few papers with more sophisticated approaches related to measuring >> distance in ontologies [3,4,5], which might be helpful. > > It's really funny that the second paper you're suggesting me has been > done by researchers in the same laboratory of the same university i'm > actually working in :) so i thank you for your suggestion and i will > probably go ask them some suggestion about distance metrics. If you meet Francesca Lisi or Nicola Fanizzi, send them my regards. :-) >>> Is there some kind of limitation i'm not aware of that can >>> stop me doing what i described? >> >> In your description, you assume that there is one class for each object. >> In general, an object can be instance of several classes. In particular, >> it can also belong to several "most specific" classes. However, this >> does seem to be rare in the DBpedia ontology (and you can generalise the >> above description to this case). > > Ok i get it. Now for example let's take: > > http://dbpedia.org/page/Bari > > (my home town). the rdf:type property (wich i'm assuming is the one > useful for the maping) gives back: > > rdf:type <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> > > * dbpedia-owl:Place <http://dbpedia.org/ontology/Place> > * dbpedia-owl:Area <http://dbpedia.org/ontology/Area> > * dbpedia-owl:Resource <http://dbpedia.org/ontology/Resource> > * dbpedia-owl:PopulatedPlace > <http://dbpedia.org/ontology/PopulatedPlace> > * http://dbpedia.org/class/yago/AncientGreekCities > * http://dbpedia.org/class/yago/CitiesAndTownsInApulia > * http://dbpedia.org/class/yago/CoastalCitiesAndTownsInItaly > * http://dbpedia.org/class/yago/PortCitiesInItaly > > > Googling yago i've found it's an ontology based on wordnet structer > (more or less). By the way as you told me the classes are one more > specific than another. Is there a way to determinate how "deep" a class > is other than calculating a path to owl:Thing ? I'm asking this because > right now i'm thinking of mapping an instance to one class, maybe the > most specific one, by te way i may find come other ways like map to > every class and than take the deepest... i don't know i will have to > think a bit more about this :) DBpedia has different class hierarchies (DBpedia ontology, YAGO, OpenCyc, Umbel), which you should not mix in your approach. See Section 3.2 in our latest DBpedia paper [2] for an overview. The DBpedia ontology has the prefix http://dbpedia.org/ontology/. Since we currently store all types of an entity (Place, Area, PopulatedPlace) for an entity and not just the most specific one (PopulatedPlace), you could also calculate the depth by just counting the number of classes. This works if there is a single most specific class and we keep storing all more general classes in the SPARQL endpoint (which might change in the future). Kind regards, Jens -- Dipl. Inf. Jens Lehmann Department of Computer Science, University of Leipzig Homepage: http://www.jens-lehmann.org GPG Key: http://jens-lehmann.org/jens_lehmann.asc ------------------------------------------------------------------------------ Enter the BlackBerry Developer Challenge This is your chance to win up to $100,000 in prizes! For a limited time, vendors submitting new applications to BlackBerry App World(TM) will have the opportunity to enter the BlackBerry Developer Challenge. See full prize details at: http://p.sf.net/sfu/Challenge _______________________________________________ Dbpedia-discussion mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/dbpedia-discussion
