Refining occurrences

Occurrence is a resource attached to a topic. Topic Maps standards defines occurrence as the instance of subject, the topic represents. However, usually occurrence is thought more generally a property of the topic. Occurrence resource can be almost anything. Usually occurrence resource is an URL addressing networked resource or a literal, a resource itself. In the URL resource, the resource data is stored outside a topic map while the literal resource is in the topic map. Wandora supports only literal resources although Wandora may handle the literal as an URL. A literal resource is essentially a text.

Because an occurrence is a text fragment, it is probable it contains information that somehow relates to the topic carrying the occurrence. Saying this out, it becomes quite natural to ask a question how one could distill associations out of occurrence resources.