"Not equivalent to" in LaTeX [closed]

I want to do a $\Longleftrightarrow$ with a dash over it, indicating "A is NOT equivalent to B", but $\not \Longleftrightarrow$ does not center the dash. This looks ugly. Are there other solutions?

1 Answer

The centernot package provides this functionality:

\documentclass{article} \usepackage{centernot} \begin{document} $A \Longleftrightarrow B \centernot{\Longleftrightarrow} C$ \end{document} 

Reference: How to negate a specific symbol?