for A1 being SetSequence of {1,2,3,4}
for w being Real st ( w = 2 or w = 4 ) & ( for n being Nat holds
( A1 . n = {} or A1 . n = {1,2} or A1 . n = {3,4} or A1 . n = {1,2,3,4} ) ) holds
{w} <> Intersection A1