A double-lined rightward arrow indicating logical implication or strong consequence in mathematical proofs and logic.
Examples
Logical implication with emphasis
P \land Q \Longrightarrow R
Mathematical proof step
x^2 = 4 \Longrightarrow x = \pm 2
Function composition implication
f \text{ continuous}, g \text{ continuous} \Longrightarrow f \circ g \text{ continuous}