# Typesetting a nested \lrcorner?

I'd like to create the symbol below, with a "nested" \lrcorner. How is this possible?

• How are you going to use this? You can draw it with picture (loading pict2e package). – Manuel Jul 21 '16 at 11:26
• @Manuel I want to use this symbol for homotopy pullbacks in commutative diagrams. – Arrow Jul 21 '16 at 11:56

Here's a solution with the \stackinset command, from stackengine:

\documentclass[11pt, border=5pt]{standalone}
\usepackage{amssymb}
\usepackage{stackengine}
\newcommand\Lrcorner{\mathclose{\ensurestackMath{\stackinset{l}{0.018em}{t}{0.01em}{\scriptstyle\lrcorner} {\lrcorner}}}}

\begin{document}

$\Lrcorner$

\end{document}


[Steven B. Segletes edit] follows:

\documentclass[11pt, border=5pt]{standalone}
\usepackage{amssymb}
\usepackage{stackengine}
\newcommand\Lrcorner{\mathclose{\ensurestackMath{\stackinset{l}{0.018em}{t}{0.01em}{\ooalign{$\scriptstyle\lrcorner$\cr\raisebox{-.1pt}{\kern.1pt$\scriptstyle\lrcorner$}}} {\lrcorner}}}}

\begin{document}

$\Lrcorner$

\end{document}


[Bernard edit] This code gives both \lrcorners and \ulcorners. They have exactly the same line thickness:

\documentclass[11pt, border=5pt]{standalone}
\usepackage{amssymb, amsmath}
\usepackage{stackengine}

\newcommand\LRcorner{\mathclose{\stackinset{l}{0.004em}{t}{-0.09em}{\rlap{\clipbox{0pt -0.3pt 0.15em 0pt}{$\lrcorner$}}\hspace{-0.093em}\clipbox{0pt 0.09em 0pt 0pt}{$\lrcorner$}}{$\lrcorner$}}}
\newcommand\ULcorner{\mathopen{\stackinset{r}{0.005em}{t}{0.1em}{\rlap{\clipbox{0pt 0pt 0pt 0.1em}{$\ulcorner$}}\hspace{0.07em}\raisebox{-0.1em}{\clipbox{0.175em 0pt 0pt 0pt}{$\ulcorner$}}}{$\ulcorner$}}}

\begin{document}

$\ulcorner \ULcorner \mathrm B \LRcorner \lrcorner$

\end{document}


• Thanks! How is it possible to make both symbols of the same thickness? – Arrow Jul 21 '16 at 11:05
• I just knew @Arrow was going to ask that. – Steven B. Segletes Jul 21 '16 at 11:06
• @StevenB.Segletes How come? :D – Arrow Jul 21 '16 at 11:07
• I'm afraid you should design a new character using TikZ or pstricks… – Bernard Jul 21 '16 at 11:08
• @Arrow Because I've used Bernard's trick enough times to have heard that same reply often. I have edited Bernard's answer to give you another possibility. – Steven B. Segletes Jul 21 '16 at 11:11

This answer uses the roundrule package, found exclusively at the end of this answer: Is there such a thing as a \mathrule? (rounded endcaps). It provides three parameters to tweak the design:

1. \LRthk is the rule thickness;

2. \LRwd is the width of the symbol (not counting the 1pt buffer on both sides); and

3. \LRfrac is the relative size of the small corner to the large corner.

Here is the MWE.

\documentclass{article}
\usepackage{roundrule}
\usepackage{stackengine,amssymb}
\newlength\LRthk
\newlength\LRwd
\LRthk=.08ex\relax
\LRwd=.91ex\relax
\def\LRfrac{.75}
\def\Bcorner{\roundrule[-\LRfrac\LRthk]{\LRwd}{\LRthk}\kern-\LRthk%
\roundrule[-\LRfrac\LRthk]{\LRthk}{\LRwd}}
\def\Lcorner{\roundrule[-\LRfrac\LRthk]{\LRfrac\LRwd}{\LRthk}\kern-\LRthk%
\roundrule[-\LRfrac\LRthk]{\LRthk}{\LRfrac\LRwd}}
\newcommand\LRcorner{%
\mathclose{\kern1pt\stackinset{l}{}{t}{}{\Lcorner}{\Bcorner}\kern1pt}}
\begin{document}
$\lrcorner\LRcorner x$
\end{document}