# why won't my file containing nexist compile

I am trying to use the 'does not exist' symbol in latex as it is defined here. I am using TeXstudio for mac.

This Latex file compiles fine:

\documentclass{article}\usepackage{amsmath}
\usepackage{graphicx}\usepackage{listings}
\usepackage{amsfonts}
\begin{document}
$\exists$
\end{document}


While this file won't compile

\documentclass{article}\usepackage{amsmath}
\usepackage{graphicx}\usepackage{listings}
\usepackage{amsfonts}
\begin{document}
$\nexists$
\end{document}


And gives me this error message

Undefined control sequence. $\nexists  In case this is relevent, I have included some information about the software and my computer: About TeXstudio: TeXstudio 2.12.8 (hg 2.12.8) Using Qt Version 5.10.0, compiled with Qt 5.10.0 R About my mac: MacBook Pro (Retina, 15-inch, Mid 2015) macOS Catalina Version 10.15.4 (19E287) ## 1 Answer Use amssymb in your preamble so you can use \nexists %!TEX program = lualatex \documentclass{article} \usepackage{amsfonts} \usepackage{amsmath,amssymb} \usepackage{graphicx} \usepackage{listings} \begin{document}$\nexists\$
\end{document}


• thank you, this works, however I would also like to know why nexists is not included yet exists is. This distinction is not made clear on the website I linked to. – mathew Apr 20 at 2:10
• As I can see, it is not defined by LaTeX, so you should use a package. Use detexify.kirelabs.org/classify.html to search LaTeX symbols (it also shows the packages needed to use the symbols) – JairoADelRio Apr 20 at 2:13
• I suppose that's because in LaTeX math typesetting you usually load the trio amsmath, amssym. amsthm so you don't care about most symbols. – JairoADelRio Apr 20 at 2:14
• The reason \nexists is not in the basic (La)TeX symbol set is historical. The original symbol set included only what was needed for Donald Knuth's "The Art of Computer Programming". When TeX became more widely used, additional symbols were created and made available by and for different disciplines -- mathematics, physics, linguistics, ..., as TeX was adopted by those communities. – barbara beeton Apr 20 at 3:07
• @fred you may think exists and nexists have some relation and should go together, but tex just sees them as two symbols and the core tex fonts only have one of them so adding nexists is like adding cyrillic, you need to load an additional font. You could use \not\exits but that constructs an over-struck symbol so not as good. – David Carlisle Apr 20 at 7:21