SkosCoreGuideToc/SectionConcept
Declaring a Concept
The 'concept' is the fundamental unit you can describe using SKOS Core.
An RDF description of a concept begins with something like the following:
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:skos="http://www.w3.org/2004/02/skos/core#"> <skos:Concept rdf:about="http://my.example.org/knowledgebase/biology#evolution"/> </rdf:RDF>
It is worth noting that the above snippet of RDF/XML is the equivalent shorthand form of the following:
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> <rdf:Description rdf:about="http://my.example.org/knowledgebase/biology#evolution"> <rdf:type rdf:resource="http://www.w3.org/2004/02/skos/core#Concept"/> </rdf:Description> </rdf:RDF>
In this guide, the shorthand form is used throughout for clarity.
Also note that the URI http://my.example.org/knowledgebase/biology#evolution
is here an identifier for an abstract concept. It is not the URL of a document fragment.
For more on URIs for concepts, see the later section [ref concept URIs].
End section
Previous drafts ...
AJM first draft>
... defining a concept
SKOS Core talks about Concept and Concept Scheme. These terms were chosen because thesauri, terminologies, controlled vocabularies, glossaries etc. can all be modelled as consisting fundamentally of a set of concepts (i.e. ideas, notions). In this guide, Concept is used to refer to the fundamental unit of a thesaurus or controlled vocabulary, and Concept Scheme refers to a set of concepts, and including (optionally) a set of relationships between those concepts.
When it comes to using SKOS Core for things like blog category schemes and web directories, it get's a little hazy as to whether the fundamental units of these things should be called 'concepts' or not. ... @@TODO clarify ... If a thesaurus gets used in a similar way to a blog category scheme or a web directory, then it can be useful to treat their fundamental units in a similar way. So if it helps you to think of a blog category as a 'concept' then that's great. If it doesn't, don't worry about it.
I'm going to use a set of examples to illustrate how to use SKOS Core (and other vocabularies) to build up an RDF description of a concept and a concept scheme.
An RDF description of a concept begins with something like the following:
<rdf:RDF @@TODO XMLNS> <skos:Concept rdf:about="http://isegserv.itd.rl.ac.uk/topics/102"/> </rdf:RDF>
This snippet of RDF/XML basically says '<http://isegserv.itd.rl.ac.uk/semwebtopics/102> is a skos:Concept'.
It is worth noting that the above example is in fact shorthand for the following:
<rdf:RDF> <rdf:Description rdf:about="http://isegserv.itd.rl.ac.uk/topics/102"> <rdf:type rdf:resource="http://www.w3.org/2004/02/skos/core#Concept"/> </rdf:Description> </rdf:RDF>
Throughout this guide, the shorthand form is used for clarity.