\ZThe symbol \Z is used to denote the set of all integers in mathematical notation. It is a standard symbol in set theory and number theory, representing the set of whole numbers including positive, negative, and zero.
x is an integer
x \in \ZThe square of any integer is non-negative
\forall n \in \Z, n^2 \geq 0The set of all integers
\Z = \{ ..., -3, -2, -1, 0, 1, 2, 3, ... \}