Events which do not intersect are said to be 'separated.' A 'separated set' of events is a set of events of which any two are separated from each other.
28.2 A 'dissection' of an event is a separated set such that the set of intersectors of its members is identical with the set of intersectors of the event. Thus a dissection is a non-overlapping exhaustive analysis of an event into a set of parts, and conversely the dissected event is the one and only event of which that set is a dissection. There will always be an indefinite number of dissections of any given event.
If
, there are dissections of
of which
is a member. It follows that if