One of the readings for my course on topic maps is the TAO of Topic Maps.
I was re-reading it the other day while writing a lecture.
Topics can represent anything. That much we all know.
Associations represent “a relationship between two or more topics.”
Isn’t an association an “anything?”
Occurrences are “information resources that are deemed to be relevant to the topic in some way.”
Isn’t an occurrence an “anything?”
Which would mean that both association and occurrences could be represented by topics, but their not.
They have special constructs in ISO 13250. And defined sets of properties.
I thought about that for a while and it occurred to me that topic, association and occurrence are just convenient handles for bundles of properties.
When I say “association,” you know we are about to talk about a relationship between two subjects (topics), their roles, role players, etc.
Same goes for occurrence.
Or to put it differently, “topic,” “association” and “occurrence” facilitate talking about particular subjects and their properties.