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Logic Symbols

Basics on symbols

Here’s a minimal list of common symbols and the Greek alphabet. (You will find a lot of useful information from the sidebar of this Overleaf site.)
The AMS LaTeX page tells you about some key standard packages, including the ams symbols package: mathtools.sty adds possibly useful functionality. Consult the AMS short guide to maths setting for lots of basic symbols.
A quick way of finding symbols is provided by Detexify – you draw a symbol in a box in your browser, and it cleverly finds LaTeX matches!

The symbol bible

Scott Pakin’s wonderful Comprehensive LaTeX Symbol List– now a mere 20000+ to choose from. For example, consult the index for
- “definite description” for two solutions for an inverted iota definite description operator (or a slight tweak is to put \usepackage{kpfonts} in the preamble and then use {\text{\rotatebox[origin=c]{180}{$\iotaup$}}).
- “par” for inverted “&” for linear logicians.
- “iddots” for mathdots command to get three dots going up from south-west to north-east.
- “alphabets, math” for more alphabets for symbols [in particular, note the package mathrsfs which provides script capitals]..

Special symbol solutions

Negation: To use old-style “~” for negation, define a command such as \oldneg" in the preamble by \newcommand*{\oldneg}{\mathord{\sim}}. (NB The \sim symbol is pre-defined as a relation symbol and writing $\sim P$ will produce an unwanted space between the symbols, while $\oldneg P$ will now, as wanted, produce $\sim\!\!P$.)
Corner quotes: A page on how to set corner quotes (e.g. for Gödel numbers) at the right height (Sam Buss, Heiko Oberdiek).
Double square brackets (indicating semantic evaluation): “” and “” are in the stmaryrd package, so you can use them by putting \usepackage{stmaryrd} in the preamble.
More conditionals: e.g. the “strictif” for the fish-hook sign for strict implication, “boxright” for Lewis’s symbol for the counterfactual, and other Lewisian symbols. These are part of the txfonts and pxfonts packages, which are intended for use with the Times Roman and Palatino fonts, respectively. But (thanks to Richard Zach for this), you can access them e.g. while still using Computer Modern by having the txfont package available and putting this in the preamble to declare the commands \strictif and \boxright:
```
\DeclareSymbolFont{symbolsC}{U}{txsyc}{m}{n}
\DeclareMathSymbol{\strictif}{\mathrel}{symbolsC}{74}
\DeclareMathSymbol{\boxright}{\mathrel}{symbolsC}{128}
\DeclareMathSymbol{\boxRight}{\mathrel}{symbolsC}{136} % 'would' 
\DeclareMathSymbol{\diamondRight}{\mathrel}{symbolsC}{140} % 'might'
\DeclareMathSymbol{\diamonddot}{\mathord}{symbolsC}{144} 
```
Similarly of course for invoking other symbols you want. To get the number for a symbol to use with you can use AI.
A triple turnstile to match the usual single and double turnstiles? A solution here.
Other turnstiles: For constructing a considerable variety of turnstile symbol, there is a dedicated turnstile package. Updated 3 June 2026