# Symbol for "not absolutely continuous" in Latex

I have trouble finding the symbol which indicates that two measure are not absolutely continuous i.e. the negation of $\mu \ll \nu$. Anyone has an idea how to write this?

Edit 1:

• Can you add an image?
– gigi
Jun 23 '19 at 13:52
• Just added one, sorry for my drawing skills. Jun 23 '19 at 13:56

The \centernot package is made for that:

\documentclass{article}
\usepackage{amsmath,centernot}

\newcommand{\nll}{\centernot{\ll}}

\begin{document}

$a\ll b$

$a\nll b$

\end{document}


txfonts has \nll:

\documentclass{article}

\usepackage{txfonts}

\begin{document}

$\nll$

\end{document}


MnSymbol also has this letter:

\documentclass{article}

\usepackage{MnSymbol}

\begin{document}

$\nll$

\end{document}


• Nice findings :-) However the txfonts package is deprecated for a while now. You should replace that with newtxtext and newtxmath for text and math fonts, respectively. Jun 23 '19 at 14:52

In the modern toolchain, \not\ll appears to work fine with most Unicode math fonts. You can declare \newcommand\nll{\mathrel{\not\ll}} if you prefer.

\documentclass{article}
\usepackage{unicode-math}

\begin{document}
$$\not\ll$$
\end{document}


As always with unicode-math, compile with LuaLaTeX or XeLaTeX.

You can build the symbol by superimposing the \ll with a /:

\documentclass{article}
\makeatletter
\newcommand{\nll}{\mathrel{\mathpalette\@nll{}}}
\def\@nll#1#2{\m@th\ooalign{\hfil$#1\ll$\hfil\cr\hfil$#1/$\hfil\cr}}
\makeatother
\begin{document}
$$\mu\nll\nu$$

$$a^{\mu\nll\nu}$$

$$a^{b^{\mu\nll\nu}}$$
\end{document}


A simple solution for the default font:

\documentclass{article}
\newcommand{\nll}{\mathrel{\not{\mkern -7mu\ll}}}

\begin{document}

$\mu\nll \nu$

\end{document}


Edit by comment: using a macro \notll to obtain your symbol.

\documentclass[a4paper,12pt]{article}
\usepackage{amsmath,amssymb}
\newcommand{\notll}{\makebox[0pt][l]{$\mkern10mu/$}\ll}
\begin{document}
$a\notll b$
\end{document}

• Probably better to call your symbol \notll, since \negll suggest \neg, which is the ¬ symbol. (OMG! I actually used that thing on my keyboard for probably the first time in thirty years of using PCs! Thank you, Sebastiano!) Jun 25 '19 at 13:39
• @DavidRicherby Approved! Thank you. Jun 25 '19 at 22:02

Using the most basic, standard tool, namely the \not operator which can negate any operator by crossing it with a slash.

\documentclass{article}

\begin{document}
$\mu \not\ll \nu$.

$a \not < b$.

$x\not \ge y$.
\end{document}