A double-lined leftward arrow symbol commonly used to denote logical implication or mapping relationships in formal logic and category theory.
Examples
Logical equivalence (if and only if), left direction
x^2 = 4 \Longleftarrow x = 2 \text{ or } x = -2
Category theory functor relationship
F(A) \Longleftarrow F(B) \text{ in category } \mathcal{C}
Mathematical proof with logical implication
\text{Statement A} \Longleftarrow \text{Statement B} \Longleftarrow \text{Statement C}