One of These Things could be a theme song for topic maps.
It is also a good idea for a topic map authoring interface.
Say you get ten (10) “hits” back from a search. Add a “checkbox” to each “hit.” Unchecked means same as other unchecked “hits.” Checked means different from the unchecked “hits.”
The “same subject” judgment becomes a collective one of all the users of the search interface. Different “hits” are going to be unchecked in any search return.
Semantic input = Human input.