Brumer bound

The Brumer bound is a concept from number theory, specifically in the study of algebraic number fields and their units. In the context of Class Field Theory and the study of the structure of units in the ring of integers of a number field, the Brumer bound provides a way to estimate the size of units in the ring of integers of an algebraic number field. More formally, it is a bound on the regulator of the unit group of the field's integers.