The foaf:primaryTopic
property relates a document to the
main thing that the document is about.
The foaf:primaryTopic
property is functional: for
any document it applies to, it can have at most one value. This is
useful, as it allows for data merging. In many cases it may be difficult
for third parties to determine the primary topic of a document, but in
a useful number of cases (eg. descriptions of movies, restaurants,
politicians, ...) it should be reasonably obvious. Documents are very
often the most authoritative source of information about their own
primary topics, although this cannot be guaranteed since documents cannot be
assumed to be accurate, honest etc.
It is an inverse of the foaf:isPrimaryTopicOf
property, which relates a
thing to a document primarily about that thing. The choice between these two
properties is purely pragmatic. When describing documents, we
use foaf:primaryTopic
former to point to the things they're about. When
describing things (people etc.), it is useful to be able to directly cite documents which
have those things as their main topic - so we use foaf:isPrimaryTopicOf
. In this
way, Web sites such as Wikipedia or NNDB can provide indirect identification for the things they
have descriptions of.