Briefly, owl:Thing --> The class of OWL individuals *Object properties* connect pairs of individuals. *Data properties* connect individuals with literals
In Jena, now, let's say you have a Statement instance getSubject <https://jena.apache.org/documentation/javadoc/jena/org/apache/jena/rdf/model/Statement.html#getSubject--> () will give you Statement's subject as an instance of Resource. getURI <https://jena.apache.org/documentation/javadoc/jena/org/apache/jena/rdf/model/Resource.html#getURI--> () on that Resource will get you a String with the URI of the subject, or null if it is a blank node getObject() will give you Statement's subject as an instance of RDFNode on this RDFNode you can use isLiteral() and isResource() to determine what it is. Of course there are other methods, you can use to get the same results. . On Tue, Sep 6, 2016 at 4:32 PM, Jérémy Coulon <[email protected]> wrote: > Thank you for your answers. > I think I am in the case you described by "There is also the possibility to > use simple SPARQL to determine whether a graph meets some conditions of > interest and then take action in application code accordingly." > I would like to retrieve the rdfs:range of a property and take actions > accordingly. > This is the reason why I would like to make a distinction between ranges > that could be rdfs:Literal (or a subclass of Literal) and ranges that are > "URIs or BlankNodes". > > What is the meaning of owl:Thing exactly ? > What is the meaning of owl:ObjectProperty vs. owl:DatatypeProperty ? > > > On Tue, Sep 6, 2016 at 2:02 PM, A. Soroka <[email protected]> wrote: > > > This is a very common misunderstanding, and we can correct it even more > > generally: _nothing_ in RDFS _or_ OWL can be used to restrict the triples > > in a graph, ever, under their specified semantics [1]. They can only be > > used to create new triples, not to disallow triples. SPIN (or > > implementations of the forthcoming SHACL specification) are indeed a more > > reasonable approach. There is also the possibility to use simple SPARQL > to > > determine whether a graph meets some conditions of interest and then take > > action in application code accordingly. > > > > --- > > A. Soroka > > The University of Virginia Library > > > > [1] There is an alternative closed-world semantics for OWL called ICV, > but > > I am not sure how easy it would be to use with Jena. It is implemented in > > Pellet, but this documentation for Pellet (https://github.com/ > > Complexible/pellet/wiki/FAQ#jena-interface) refers to DIG, so it seems > > rather out of date. > > > > > On Sep 6, 2016, at 5:41 AM, Nikolaos Beredimas <[email protected]> > > wrote: > > > > > > I think you are misunderstanding the meaning of rdfs:range (a very > common > > > mistake) > > > Per definition, > > > rdfs:range is an instance of rdf:Property > > > <https://www.w3.org/TR/rdf-schema/#ch_property> that is used to state > > that > > > the values of a property are instances of one or more classes. > > > > > > So, rdfs:range is not supposed to be used to restrict the "kind" of an > > > object, but to infer it. > > > > > > If you want restrictions, try something like SPIN. > > > > > > Regards, > > > Nikos > > > > > > On Tue, Sep 6, 2016 at 12:34 PM, Jérémy Coulon < > > [email protected] > > >> wrote: > > > > > >> Hello, > > >> > > >> I would like to write my own ontology. > > >> For some properties I would like to restrict their range to URIs or > > >> BlankNodes but to forbid literals. > > >> For example: > > >> myprop a rdf:Property ; > > >> rdfs:range ***URIs or BlankNodes*** . > > >> > > >> I have difficulties to understand some semantics of RDFS and OWL. > > >> I don't see a way to do what I want with pure RDFS. > > >> I have read about owl:Thing but I don't understand what it is supposed > > to > > >> mean. > > >> Is owl:Thing the range I am looking for ? > > >> Is it possible to do what I need after all ? > > >> > > >> Thanks for your help. > > >> > > >> Jeremy > > >> > > > > >
