Implies (⇒) and does not imply (⇏) symbol in LaTeX

In order to use implies symbol in LaTeX, you can use the default command \Rightarrow command or the \implies command with amsmath package. But both of these commands provide slightly different outputs of this symbol. Take a look.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
   
  $$ \verb|\Rightarrow| : \Rightarrow $$
  $$ \verb|\implies| : \implies $$

\end{document}

Output:

Implies symbol with other packages

You can also use other packages to get different styles of implies symbols. Follow the table given below.

Package	Command	Output
None	$\Rightarrow$
None	$\Longrightarrow$
amsmath	$\implies$
MnSymbol	$\Rightarrow$
MnSymbol	$\Longrightarrow$
fdsymbol	$\Rightarrow$
fdsymbol	$\Longrightarrow$

Does not imply (⇏) symbol in LaTeX

In order to get the Does not imply symbol in LaTeX, you can use the centernot package and \centernot command with the \Longrightarrow and \implies command. Take a look.

\documentclass{article}
\usepackage{pifont}
\usepackage{amsmath}
\usepackage{centernot}
\begin{document}

  $$ \verb|\centernot\Rightarrow| : \centernot\Rightarrow \text{\ding{55}} $$
  $$ \verb|\centernot\Longrightarrow| : \centernot\Longrightarrow \text{\ding{51}} $$
  $$ \verb|\centernot\implies| : \centernot\implies \text{\ding{51}} $$

\end{document}

Output: