8

How can I write the symbol

enter image description here

for a proper ideal?

The standard relations \leq,\subseteq both have a "proper" version \lneq,\subsetneq, but I was unable to find a "proper" version of either \unlhd or \trianglelefteq.

Any suggestions?

9

You can do by superimposing the symbols:

\documentclass[a4paper]{article}
\usepackage{amssymb}

\newcommand{\properideal}{%
  \mathrel{\ooalign{$\lneq$\cr\raise.22ex\hbox{$\lhd$}\cr}}}

\begin{document}
$I\properideal A$
\end{document}

enter image description here

A version that changes size in subscripts/superscripts; some artifacts may appear at low screen resolution.

\documentclass[a4paper]{article}
\usepackage{amsmath}
\usepackage{amssymb}

\makeatletter
\DeclareRobustCommand{\properideal}{\mathrel{\text{$\m@th\proper@ideal$}}}
\newcommand{\proper@ideal}{%
  \ooalign{$\lneq$\cr\raise.22ex\hbox{$\lhd$}\cr}%
}
\makeatother
\begin{document}
$I\properideal A_{\properideal_{\properideal}}$
\end{document}

enter image description here

  • 1
    Is there any other way of doing this? The $<$ bit of this symbol is bold when I put it into a document, which is less than ideal... – user1729 May 9 '12 at 15:36
  • @user1729 Maybe a follow-up question with a minimal example is better. – egreg May 9 '12 at 15:38
  • I was contemplating asking a new question, but I thought I would ask briefly here first. What do you mean by "a minimal example"? – user1729 May 9 '12 at 15:43
  • An example of a .tex document that exhibits the problem, including all necessary packages. Don't forget a link to this question. – egreg May 9 '12 at 15:50
  • I think I'll wait until I've got a printed out a copy of the document before asking the question - I'm starting to worry it is just my screen playing tricks on me! (Although, for the record, my "minimal example" is exactly what you have written, above.) – user1729 May 9 '12 at 15:59

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