The List Set Generator: A Construct for Evaluating Set Expressions
The list set generator is defined and algorithms
for its use are given.  The list set generator is
a construct which may be added to a list processing system or any
system that handles sets.  It efficiently generates the set which
results from any expression involving sets and set operators.  The
efficiency derives from evaluating the expression as a whole and
in parallel, rather than evaluating subexpressions and
then using those sets to arrive at the final result.
CACM December, 1970
Shapiro, S. C.
