1

I would like to make 2 implication arrows on top of one another, facing opposite directions, such that the bottom one is actually a not implies. I would also like to be able to label these arrows with text.

  • 1
    Welcome to TeX SX! Should these arrows be extensible in function of the text? – Bernard Apr 23 at 22:32
  • Maybe you want to have a look here and see if you can modify it to your needs. – user121799 Apr 23 at 22:46
3

Does that answer me as described in your question? There are three types of examples, with the hope that I have answered correctly.

enter image description here

\documentclass[a4paper,12pt]{article}
\usepackage{amsmath,amssymb}
\usepackage{scalerel}

\begin{document}
\[a\mkern10mu\Rightarrow \mkern-30mu\nLeftarrow\mkern10mu b\]
\[a \nLeftrightarrow b\]
\[a \overset{\,\scaleobj{1.5}{\Rightarrow}}{\nLeftarrow} b\]
\end{document}
1

A version which is correctly centred on the math axis and scales accordingly to the math style.

\documentclass{article}

\usepackage{amssymb}

\def\impliesnotimpliedby{\mathrel{\mathpalette\impliesnotimpliedbyaux\relax}}
\def\impliesnotimpliedbyaux#1#2{%
  \vcenter{%
  \offinterlineskip
  \hbox{$#1\;\Rightarrow$}\vskip.3ex\hbox{$#1\nLeftarrow$}
  }%
}

\begin{document}

\[
A \impliesnotimpliedby B_{A \impliesnotimpliedby B_{A \impliesnotimpliedby B}}
\]

\end{document}

enter image description here

  • Then the last of the three I've written is like yours and I'm glad. Your code is better than mine surely. – Sebastiano Aug 19 at 15:40

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