To demonstrate the optimized version:

#first set generates normally
ABCD	#ABCD is the first set, store internally
BCD
ACD
ABD
ABC
AB
AC
BC
AD
BD
CD
A
B
C
D
#second set ABE -> look at slots A, B, E. All are the same, so arbitrarily check against "A" (ABCD)
is ABE a subset of ABCD? 
	NO -> print	#ABE is the first set, store internally
is AB a subset of ABCD?
	YES -> skip
is AE a subset of ABCD?
	NO -> print
is BE a subset of ABCD?
	NO -> print
is A a subset of ABCD?
	YES -> skip
is B a subset of ABCD?
	YES -> skip
is E a subset of ABCD?
	YES -> skip
#third set
is ABC a subset of ABCD?
	YES -> skip	
#generates nothing, stores nothing
#fourth set -> look at slots "E", "F". "F" is the smallest (empty), so we need to do -no- checks.
EF
E
F

We store 9 bytes and do 10 checks (determining "no checks" counts as a check). Note - the original
powerset version would also require 10 checks, so we're optimal here.