The set of all elements in the universal set that is not in set A is called the complement of set A.
In set theory, the complement of a set includes everything in the universal set that does not belong to the specified set. If we denote the universal set as U and set A as a subset of U, then the complement of set A, often written as A’, is defined as:
A’ = { x ∈ U | x ∉ A }
In simpler terms, A’ includes every element that exists in U but is not part of A. This concept is vital in various fields of mathematics and helps in understanding relationships between different sets.