Labelling Concepts

To describe the preferred and alternative labels for a concept, do for example 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/bloggers/topics#102">
    <skos:prefLabel>Semantic Web</skos:prefLabel>
    <skos:altLabel>SemWeb</skos:altLabel>
    <skos:altLabel>SW</skos:altLabel>
  </skos:Concept>

</rdf:RDF>

Another example, adapted from the UK Government Category List [ref], would be:

<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/GCL/492#concept">
    <skos:prefLabel>Equal opportunities and diversity</skos:prefLabel>
    <skos:altLabel>Positive discrimination (equal opportunities)</skos:altLabel>
    <skos:altLabel>Racial discrimination (education opportunities)</skos:altLabel>
    <skos:altLabel>Racial discrimination (employment opportunities)</skos:altLabel>
    <skos:altLabel>Racial equality</skos:altLabel>
    <skos:altLabel>Religious discrimination (education and employment)</skos:altLabel>
    <skos:altLabel>Sexual discrimination (education opportunities)</skos:altLabel>
    <skos:altLabel>Sexual discrimination (employment opportunities)</skos:altLabel>
    <skos:altLabel>Discrimination by sex, race, religion, etc</skos:altLabel>
    <skos:altLabel>Diversity (equal opportunities)</skos:altLabel>
    <skos:altLabel>Affirmative action (equal opportunities)</skos:altLabel>
  </skos:Concept>
  
</rdf:RDF>

Note that a concept may have no more than one preferred label per language (see also the section [multilingual concept schemes]).

End section

Previous drafts ...

AJM first draft>

A concept is quite useless without any labels that help us (as people) identify what it means. It you are only interested in adding a single label to a concept, you can use the rdfs:label property, for example:

<rdf:RDF>
   <skos:Concept rdf:about="http://isegserv.itd.rl.ac.uk/topics/102">
      <rdfs:label>The Semantic Web</rdfs:label>
   </skos:Concept>
</rdf:RDF>

Preferred and Alternative Labelling

However, it can often be useful to assign a preferred label, and then a set of alternative labels. This can be done using the skos:prefLabel and skos:altLabel properties, for example:

<rdf:RDF>
   <skos:Concept rdf:about="http://isegserv.itd.rl.ac.uk/topics/102">
      <skos:prefLabel>The Semantic Web</skos:prefLabel>
      <skos:altLabel>SemWeb</skos:altLabel>
      <skos:altLabel>SW</skos:altLabel>
   </skos:Concept>
</rdf:RDF>

The purpose of adding alternative labels can be to help another person find the concept they are looking for. It can also help to further clarify the meaning of a complex concept or subject of interest, for example:

<rdf:RDF>
   <skos:Concept rdf:about="http://isegserv.itd.rl.ac.uk/topics/045">
      <skos:prefLabel>@@TODO from a thesaurus</skos:prefLabel>
      <skos:altLabel>@@TODO</skos:altLabel>
      <skos:altLabel>@@TODO</skos:altLabel>
   </skos:Concept>
</rdf:RDF>

@@TODO a note on adapting from thesauri.

Using SKOS Core for Thesauri

The above example has been adapted from the [@@TODO some thesaurus]. Thesauri such as [whatever] loosely conform to the standards ISO2788 and ANSI Z39.19 which dictate conventions for thesaurus construction and structure. (If you don't know thesauri, these types of thesauri are quite different from 'Roget's' or the thesaurus that comes with MS Word). These thesauri are modelled as consisting of a set of 'Preferred Terms' and a set of 'Non-Preferred Terms'. Preferred terms are mapped to non-preferred terms via a relation called 'Use For (UF)' and non-preferred terms are mapped to preferred terms via an imperative called 'Use (USE)'. An example from [whatever] is :

example of USE UF from somewhere

SKOS Core takes the perspective that such a thesaurus consists of a set of concepts. A preferred term becomes a preferred label for a concept, and the non-preffered relatives become the alternative labels for a concept. So an RDF description of the above example using SKOS Core is as follows:

<rdf:RDF>
   <skos:Concept rdf:about="http://isegserv.itd.rl.ac.uk/topics/045">
      <skos:prefLabel>@@TODO from a thesaurus</skos:prefLabel>
      <skos:altLabel>@@TODO</skos:altLabel>
      <skos:altLabel>@@TODO</skos:altLabel>
   </skos:Concept>
</rdf:RDF>

Symbolic Labels for Concepts

@@TODO

... introduction to labels, symbols,