Incidence Symbol for Geometry

Question

My professor invented a symbol for when a line and a point are geometrically incident. I added a picture and wanted to ask if someone knows how to write this in LaTex? It is a small line with a dot in the middle.

score 13 · Answer 1 · answered Apr 24 '22 at 15:56

This should be a relation symbol. It can be obtained with the sequence

\relbar \joinrel \mathrel{\!\bullet\!} \joinrel \relbar

The \relbar command typesets a minus sign considered as a relation symbol; \joinrel is a small negative space considered as a relation symbol. The \bullet is made into a relation symbol, with reduced sidebearings.

\documentclass{article}
\usepackage{amsmath}
\newcommand{\incidence}{\relbar\joinrel\mathrel{!\bullet!}\joinrel\relbar}
\begin{document}
$(\mathcal{P},\mathcal{G},\incidence)$
\end{document}

score 11 · Accepted Answer · answered Apr 23 '22 at 16:56

11

\documentclass{article}
\usepackage{tikz}

\newcommand{\incid}{%
\tikz{%
    \draw[line cap=round,line width=0.13ex] (0,0)--(3ex,0);
    \fill (1.5ex,0) circle (0.5ex);
}}

\begin{document}
$(P, G, \incid)$
\end{document}

answered Apr 23 '22 at 16:56

This is perfect, thanks. Is there an easy way to make the gaps between any input and the symbol a little wider on both sides? – calculatormathematical Apr 23 '22 at 17:23
2

No need for an answer, I figured to add \hspace in the command. – calculatormathematical Apr 23 '22 at 17:25

score 9 · Answer 3 · answered Apr 23 '22 at 16:59

Here's another solution that uses the method here for superimposing symbols.

\documentclass{article}
\usepackage{amsmath}
\usepackage{amssymb}
\makeatletter
\newcommand{\superimpose}[2]{%
  {\ooalign{$#1@firstoftwo#2$\cr\hfil$#1@secondoftwo#2$\hfil\cr}}}
\makeatother
\newcommand{\incidentsymb}{%
    \mathpalette\superimpose{%
        {\rule[0.5ex]{1.2em}{0.5pt}}%
        {\text{\textbullet}}%
    }%
}
\begin{document}
$(\mathcal{P}, \mathcal{G}, \incidentsymb)$
\end{document}

score 7 · Answer 4 · answered Apr 24 '22 at 15:46

7

The easiest way to do this is:

{-}\!{\bullet}\!{-}

Curly braces are used to suppress natural spaces; \! is a negative space.

Of course, you can use \newcommand:

\newcommand{\incid}{{-}\!{\bullet}\!{-}}

A bit thicker line:

{\bf-}\!\!{\bullet}\!\!{\bf-}

answered Apr 24 '22 at 15:46

NickKolok

657

1

+1, but, please, note that \bf has been deprecated for about 30 years. In the particular case it does exactly nothing anyway. – egreg Apr 24 '22 at 15:51

score 1 · Answer 5 · answered May 09 '22 at 08:55

Just for fun, one way that works only with luatatex. With xelatex work adding \ensuremath before \bullet, but with pdflatex also failed miserably.

\documentclass{article}
\usepackage{graphicx}    
\newcommand\incidence{\mathrel{\rotatebox{90}{\bullet\kern-.4em|}}}
\begin{document}
$(\mathcal{P}, \mathcal{G}, \incidence )$
\end{document}

Incidence Symbol for Geometry

5 Answers5