A bidirectional arrow symbol representing reversible reactions in chemistry or mutual implications in logic and mathematics.
Examples
Chemical equilibrium reaction
H_2 + I_2 \leftrightharpoons 2HI
Reversible reaction with conditions
N_2 + 3H_2 \leftrightharpoons 2NH_3, \quad T = 450°C
Mathematical equivalence relation
x \leftrightharpoons y \text{ in } R