Subgroup series

A **subgroup series** in group theory is a sequence of subgroups of a given group \( G \) that is organized such that each subgroup is a normal subgroup of the next one in the series.

In group theory, a branch of abstract algebra, a **central series** is a specific type of series of subgroups associated with a given group. It provides a way to study the structure of a group by breaking it down into simpler components.

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.

Fitting length, often used in contexts like pharmaceuticals, manufacturing, or engineering, refers to the length or dimension that is required for parts or components to fit together properly. In these contexts, achieving the correct fitting length is crucial for ensuring that components function as intended without issues such as misalignment, gaps, or mechanical failure.