* {} (de lege verzameling)
* {A}
* {B}
* {C}
* {D}
* {een, b}
* {een, c}
* {een, d}
* {b, c}
* {b, d}
* {c, d}
* {a, b, c}
* {a, b, d}
* {a, c, d}
* {b, c, d}
* {a, b, c, d}