In this chapter we consider sets the elements of which are integers.
By using integers as the universe rather than arbitrary objects,
certain optimizations are possible.
For example, we can use a bit-vector of length *N*
to represent a set whose universe is .
Of course, using integers as the universe does not preclude the use of
more complex objects,
provided there is a one-to-one mapping between those objects
and the elements of the universal set.

A crucial requirement of any set representation scheme is that
it supports the common set operations including
*union* ,
*intersection* and
set *difference* .
We also need to compare sets and, specifically,
to determine whether a given set is a subset of another.

Copyright © 1997 by Bruno R. Preiss, P.Eng. All rights reserved.