Some collectives of animals have a hierarchy of rulers. The Black Wildebeest, also known as gnu, are lead by an alpha male. In larger herds the leadership extends to the beta male, the delta male and so on to the omega male. One day a solitary wildebeest encountered the herd. Alpha challenged the stranger. The new arrival could only join the herd if knew one of the wildebeest leaders. Fortunately the answer was yes. The new gnu knew Nu.