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Latex symbol if and only if / equivalence

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How to write if and only if symbol / equivalence in Latex ? In mathematics, if and only if (iff) is a biconditional logical connective between statements, where either both statements are true or both are false.


How to write if and only if symbol / equivalence in Latex ?

You do not have to use any package:

\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\begin{document}
\noindent
A $\Leftrightarrow$ B \\
C $\Longleftrightarrow$ D
\end{document}

For a short if and only if, use \Leftrightarrow:
A $\Leftrightarrow$ B

For a long if and only if, use \Longleftrightarrow:
C $\Longleftrightarrow$ D

Liste of all arrows

If you want to see all type of Latex arrows, have a look to https://www.math-linux.com/latex-26/faq/latex-faq/article/latex-arrows

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