t dimensions of interest, 'Topobiology' by Gerald Edelman.
One finds discussed there the notion of a &quot;polymorphous set&quot;.  Such a set
is defined in a universe of discourse whose elements can be described in
terms of a fixed number k of logical features.  A &quot;polymorphous set&quot; is
one that can be defined in terms of sets whose elements have a fixed
number j of the k features.

As a rule in the following discussion, I will use upper case letters as names
for concepts and sets, lower case lett