A double-headed leftward arrow symbol representing logical implication or reverse mapping in mathematical logic and category theory.
Examples
Logical equivalence
A \lArr B \text{ means 'A if and only if B'}
Bidirectional mapping between sets
\mathbb{Z}_n \lArr \{0, 1, \ldots, n-1\}
Mathematical equivalence statement
x^2 = 4 \lArr x = \pm 2