A chief series is a strict normal series of a group with no proper normal-series refinement. Its factors are minimal normal subgroups of the appropriate quotient groups. A chief factor of a finite soluble group is elementary abelian, whereas a composition factor of a finite soluble group is cyclic of prime order. A chief factor can therefore have order larger than a prime.
The "Chief" series you are referring to might relate to a few different contexts, including literature, television, or a specific brand. However, one of the most notable references could be to the "Chief" series in the realm of literature or television featuring a character that holds a leadership position, such as Chief of Police or Chief Executive Officer, and often involves themes of crime, management, and problem-solving.
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