# Symbol for not an ideal

I'm trying to write the symbol for not an ideal. I've been using \lhd to represent an ideal so what I want is to put a line through this in the same way \neq or \nless do for \eq and \less.

Any suggestions?

• Is \not\lhd enough? Feb 4, 2015 at 9:39
• No, I tried that myself but unfortunately that produces the line before the \lhd symbol, so it's "misaligned". I want it to go through the symbol, just like I mentioned the \neq does. Feb 4, 2015 at 9:44
• I'd simply say $I$ is not an ideal of $R$. Avoid symbol inflation. Feb 4, 2015 at 9:47
• Feb 4, 2015 at 9:48
• Is \lhd a common symbol for ideals? I use it for normal subgroup. Feb 4, 2015 at 12:27

Use \centernot from the same package.

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

\begin{document}

$\centernot{\lhd}$

\end{document}


• How did you generate that large image? The one I generated with standalone and saved as png with Acrobat looks like crap. Feb 4, 2015 at 9:51
• @JuriRobl Zooming-in in SumatraPDF and capturing the screenshot. Feb 4, 2015 at 9:52
• @stephenmg you're welcome. Feb 4, 2015 at 9:53

You can use either the generated symbol \not\lhd or the complete smybol \nlessclosed, both of which are from the MnSymbol package. Depending on the symbol packages you're already using, it may change some of the symbols to it's own.

\documentclass{article}
\usepackage{MnSymbol}
\newcommand{\notlhd}{\nlessclosed}
\begin{document}
$\nlessclosed$ $\notlhd$ $\not\lhd$
\end{document}


• You may want to add that MnSymbol changes most of the available symbols. Feb 4, 2015 at 10:00
• It depends what he is using at the moment, he may already be using it? But yes, I will add that. Feb 4, 2015 at 10:01