Complex sentence: A nilpotent group "G" is a group that has a central series of finite length, an upper central series that terminates with "G" or a lower central series that terminates with.
Split into simpler sentences: A nilpotent group "G" is a group that has an upper central series that terminates with "G". Provably equivalent definitions include a group that has a central series of finite length or a lower central series that terminates with.