A horizontal arrow pointing left with an elongated shaft used to denote leftward mappings or implications in mathematics.
Examples
Left mapping notation (inverse function)
f^{-1}: \mathbb{R} \longleftarrow \mathbb{R}
Logical consequence (reading from right to left)
\text{Conclusion} \longleftarrow \text{Premise}
Reverse reaction in chemistry
2NH_3 \longleftarrow N_2 + 3H_2