Search code examples
classdotnetrdfn3

Define class hierarchy in Notation 3

I am trying to develop a simple Notation3 ontology file.

so far my code in the notation3 file is 

@prefix my: <http://www.codeproject.com/KB/recipes/n3_notation#>.
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .



my:batterycs a my:spec;
    my:preferedby my:BusinessPerson, my:LoveBird, my:MusicLover, my:Travelar;

    my:name "batteryCS".

    rdfs:Person a rdfs:Class.

I am using dotNetRdf library to read and query the ontology file. the above code in n3 file works fine. But when I Insert 

 rdfs:Woman a rdfs:Class; rdfs:subClassOf :Person .

at the end of the ontology file it occurs the error Unable to resolve the QName ':Person' seems like it cant even load the ontology to the parser.

I studied the n3 syntax from http://www.w3.org/2000/10/swap/Primer.html can somebody help me with this where I have made the mistake thanks in advance

Solution

  • Your data is invalid, you need to define the empty prefix in order to be able to refer to it in a QName such as :Person

    A QName (Qualified Name) is a syntactic shortcut which allows you to shorten URIs written in the form prefix:name where prefix must refer to a defined namespace prefix defined via a previous @prefix statement. The parser then simply looks up the prefix and concatenates it with the name part, so for example rdfs:Class is expanded to http://www.w3.org/2000/01/rdf-schema#Person in your example data.

    If a prefix is not defined then a RDF parser is expected to throw an error.

    So you need to fix your data, there are a couple of ways to do this depending on what your intent was.

    You meant to put :Person in your own my: namespace

    Simply replace :Person with my:Person

    Note that you have also referred to rdfs:Person so your data looks somewhat inconsistent

    You meant to defined an empty namespace

    Simply add the following @prefix definition:

    @prefix : <http://example.org/namespace#> .

    Where the URI is the desired namespace URI

    Aside

    What version of dotNetRDF are you using? And is the error message you quote the complete error message?

    More recent versions of dotNetRDF are supposed to give more informative error messages that should have told you that you were likely missing a prefix declaration