A double-headed horizontal arrow symbol representing logical equivalence or bidirectional implication in mathematical logic.
Examples
Logical equivalence in mathematical logic
p \lrArr q \text{ means 'p if and only if q'}
Equivalence of mathematical statements
x^2 = 4 \lrArr x = \pm 2
Set equivalence relation
A = B \lrArr |A| = |B| \text{ and } A \subseteq B