I'm trying to use this symbol in a LaTeX document I'm writing but I can't for the life of me, find how to write it in LaTeX:
The symbol means that two expressions are logicically equivalent (i.e. A |==| B)Can anybody identify the missing symbol?
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Sign up to join this communityWithout the use of packages, you could do this:
\documentclass{article}
\def\logequiv{\mathrel{\vert\mkern-3mu{=}\mkern-3mu{=}\mkern-3mu\vert}}
\begin{document}
$ A \logequiv B$
\end{document}
If you didn't like the height of the \vert
s, you could do this instead:
\documentclass{article}
\def\logequiv{\mathrel{%
\rule{.3pt}{1.3ex}\mkern-1mu{=}\mkern-8mu{=}\mkern-2mu\rule{.3pt}{1.3ex}}}
\begin{document}
$ A \logequiv B$
\end{document}
\mkern
with a negative argument removes the natural space between the two symbols. The mu
is the unit of mathematical kerning. I just played with the actual numbers until I ate up all the space. My experience is that symbols have a natural space around them in integer units of mu
, though I could be wrong.
Jan 9, 2014 at 20:26
\hspace
. Therefore, the (m)kern is the proper way to combine symbols together.
Jan 9, 2014 at 20:37
There is actually a dedicated package for typesetting symbols of this sort. They are called turnstiles and the package is called turnstile
. It is included in TeX Live and can typeset turnstiles of essentially any kind. It is actually a big improvement on what was available before which was essentially just mathematics symbols. For very simple turnstiles, I sometimes find the maths symbols look better but it really depends what you need and what the context is (e.g. where you are pulling your connective symbols from etc.) In any case, for more complex turnstiles such as this one, it is definitely the best option I'm aware of:
\documentclass{article}
\usepackage{turnstile}
\newcommand*{\myequiv}{\sdststile{}{}}
\begin{document}
The symbol you need:
\[
\myequiv
\]
A selection of other possibilities:
\[
\sststile{T}{}\quad \sdtstile{a^+}{}\quad \dtdtstile{A}{B}\quad \nsttstile{}{C}
\]
\end{document}
produces (probably - I can't check):
Note that the sample image posted in the question seems to have a slight gap on the right. I'm pretty sure that shouldn't be there.
If you don't find that symbol (I believe that there is one) as a unique character you can combine two others to obtain a very similar one.
From mathabx
package you can define
\newcommand{\myequiv}{\vDash\!\!\Dashv}
to use as $A\myequiv B$
.
mathabx
fonts change a lot of other symbols as well. there are several questions that address how to access just a few symbols from a font rather than loading the whole thing via a package.
Jan 9, 2014 at 20:11
mathabx
you could follow an approach such as tex.stackexchange.com/questions/113437/stealth-arrow-in-math/… or tex.stackexchange.com/questions/14386/….
Jan 9, 2014 at 20:40
mathabx
, you could first define \Dashv
by \newcommand{\Dashv}{\mathrel{\scalebox{-1}[1]{$\vDash$}}}
(using package graphicx
).
mathabx
package you can do a trick$\vDash\!\!\Dashv $
stix
orxits
fonts.