for x1, x2, x3, x4, x5, x6 being set st {x1,x2,x3} misses {x4,x5,x6} holds
( x1 <> x4 & x1 <> x5 & x1 <> x6 & x2 <> x4 & x2 <> x5 & x2 <> x6 & x3 <> x4 & x3 <> x5 & x3 <> x6 )