# Four line equality

I'm looking for a latex command for writing a symbol of equality with four parallel lines. I have tried to draw four lines in Detexify but it only returns the equivalence symbol of three parallel lines. Thank you!

• Untested for LaTeX, but maybe $\lower.5ex\hbox{$=$}\hskip-.8em\raise.5ex\hbox{$=$}$? – awllower Oct 11 '16 at 9:38
• Unicode lists such symbol as “strictly equivalent to”, U+2263. The only math font that provides it, as far as I can see, is STIX. – egreg Oct 11 '16 at 9:43

Here is a command, \superequiv that seems to be what you want:

\documentclass{article}

\newcommand\superequiv{\mathrel{\rlap{\raisebox{\fontdimen22\textfont2}{$=$}}\raisebox{-0.5\fontdimen22\textfont2}{$=$}}}

\begin{document}

$A \superequiv B$%

\end{document}


• Nothing. Initially, I though of using \mathrlap, which is defined by mathtools, but finally I have a solution that doesn't require it. I'll delete it. – Bernard Oct 11 '16 at 10:16

The symbol is classified in Unicode as U+2263 STRICTLY EQUIVALENT TO. The only math font providing it is, as far as I know, STIX.

\documentclass{article}

\usepackage{stix}

\begin{document}

${=\equiv\Equiv}\quad A \Equiv B_{\Equiv_{\Equiv}}$

\end{document}


With other math fonts you have to emulate it. Using the same idea as Bernard, here is a possibility with Computer Modern

\documentclass{article}

\makeatletter
\DeclareRobustCommand\Equiv{\mathrel{%
\mathchoice
{\Equiv@\textfont\displaystyle{.45}}
{\Equiv@\textfont\textstyle{.45}}
{\Equiv@\scriptfont\scriptstyle{.5}}
{\Equiv@\scriptscriptfont\scriptscriptstyle{.55}}
}}
\newcommand{\Equiv@}[3]{%
\rlap{\raisebox{#3\fontdimen5#12}{$\m@th#2 =$}}%
\raisebox{-#3\fontdimen5#12}{$\m@th#2 =$}%
}
\makeatother

\begin{document}

${=\equiv\Equiv}\quad A \Equiv B_{\Equiv_{\Equiv}}$

\end{document}


I'm afraid that, with other fonts, you have to tailor the parameter (the third argument to \Equiv@ in the code above).