[Tex/LaTex] How to type NOT \delta and NOT \ll

symbols

In proximity theory, we use \delta and \ll as binary relations on the power set of a set X. How can one display NOT \delta or NOT \ll similar to how we can do \not\in. Using \not\delta and \not\ll place the strike-through in bad positions over the \delta and \ll.

For NOT \delta, I am currently using

  • \!\!\not\!\delta

For NOT \ll, I am using

  • \hskip 0.4mm \not \hskip -0.4mm \ll

There are a few problems here. Sometimes the placement of the "not" over the "delta" is a little off but it varies throughout the pages. Also, at the end of the line, I may get the \not appearing at the end of the current line and the \delta appearing at the beginning of the next line. I have not noticed this issue with my defininition of NOT \ll.

What is the best way to define these symbols? How can one make sure that the "not" is on the same line as the "delta"?

Best Answer

Just use Heiko Oberdiek's centernot package:

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

$a\centernot\ll b \centernot\Delta c$

$a\centernot\longrightarrow b$

$a\centernot{\xrightarrow{1234567}} b$

\end{document}

enter image description here

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