A negated double arrow symbol indicating non-implication or the absence of a logical consequence between statements.
Examples
Showing non-implication in logic
A \nRightarrow B \text{ means 'A does not imply B'}
Counterexample in set theory
x > 0 \nRightarrow x > 1 \text{ (consider } x = 0.5\text{)}
Non-relationship between mathematical properties
\text{Continuous } \nRightarrow \text{ Differentiable}