Size of conjugacy class divides order of group
- If is a finite group, the size of divides the order of .
- In general, the size of is not greater (as a cardinal) than the size of .
- Size of conjugacy class divides order of inner automorphism group
- Size of conjugacy class equals index of centralizer
Analogous facts about degrees of irreducible representations
The breadth of a finite p-group is defined as the logarithm to base of the smallest of the orders of centralizers of elements. The class-breadth conjecture is a conjectured inequality relating the breadth and the nilpotency class.