I am looking for a way to set the symbol for "forking independent" (for example, see "Essential Stability Theory", Steven Buechler, p.217). It looks a bit like an anchor or an upside-down 'T' with a curved bar.
[Tex/LaTex] the LaTeX symbol for “forking independent” (model theory)
logicsymbols
Related Solutions
You could, of course, use TikZ for this:
The symbol will scale with your font size, since it uses ex to define the path.
\documentclass{article}
\usepackage{tikz}
\begin{document}
\newcommand\shield{%
\tikz [baseline] \draw (0,1.75ex) -- (0,0.75ex) arc [radius=0.75ex, start angle=-180, end angle=0] -- (1.5ex,1.75ex) -- cycle;%
}
A shield: \shield
\end{document}
If you're feeling fancy, you could parametrise it a bit:
\documentclass[border=3mm]{standalone}
\usepackage{tikz}
\begin{document}
\newcommand\shield[1][]{%
\tikzset{
shield width/.store in=\shieldwidth,
shield width=1.5ex,
shield height/.store in=\shieldheight,
shield height=1.75ex
}%
\tikz [baseline,#1] \draw (0,\shieldheight) -- (0,\shieldwidth/2) arc [radius=\shieldwidth/2, start angle=-180, end angle=0] -- (\shieldwidth,\shieldheight) -- cycle;%
}
A shield: \shield
A wide shield: \shield[shield width=2ex]
A tall shield: \shield[shield height=3ex]
\end{document}
In the Comprehensive List (texdoc symbols) one can find something near to what you want, looking for \independent. Here's a modified version:
\documentclass{article}
\makeatletter
\DeclareRobustCommand{\varamalg}{%
\mathbin{\mathpalette\var@malg\perp}%
}
\newcommand\var@malg[2]{%
\rlap{$\m@th#1#2$}\mkern6mu{#1#2}%
}
\makeatother
\begin{document}
\[
\alpha\varamalg\beta=\alpha\times\{0\}\cup\beta\times\{1\}
\]
\end{document}
Adjust \mkern6mu to suit.
Best Answer
I don't think this symbol exists in any of the typical packages, so it looks like you'll have to roll your own. You can combine the
\smilesymbol from theamssymbpackage with a\vertline for this. Here's one way to do it, based on Overlay symbol with another and \subseteq + \circ as a single symbol ("open subset").