2. Logic Symbols

  • Consult the AMS short guide to maths setting.
  • The ASL list of standard LaTeX symbols plus those provided by the package amssymb.sty (part of any standard LaTeX distribution).
  • 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!
  • Scott Pakin’s wonderful Comprehensive LaTeX Symbol List — now a mere 5913 to choose from. Consult the List’s index under …
    • “definite description” for two solutions for inverted iota definite description operator: or a slight tweak is to use {\mathrm{\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: usage "$\mathscr{LMN}$".]
  • 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} % Lewis’s stronger ‘would’ counterfactual
    • \DeclareMathSymbol{\diamondRight}{\mathrel}{symbolsC}{140} % Lewis’s stronger ‘might’ counterfactual
    • \DeclareMathSymbol{\diamonddot}{\mathord}{symbolsC}{144} % Lewis’s inner necessity

    Similarly of course for invoking other symbols you want. To get the number for a symbol to use with \DeclarMathSymbol you can use the method described at http://tex.stackexchange.com/questions/32769/find-out-the-number-of-a-symbol-to-access-it.

  • For constructing a considerable variety of turnstyle symbol, there is a dedicated turnstile package.
  • For the squiggly turnstile for non-monotonic consequence, and other symbols, there are some solutions here from Gregory Wheeler.
  • How to set corner quotes e.g. for Gödel numbers at the right height (Sam Buss).
  • Fonts for linear logicians.
  • The gene-logic package offers some enhancements — more generously spaced logic symbols plus another version of a blackboard font.
  • XeTeX users of course have more font options: they can use the unicode-math package to access fonts such as the Asana-Math OpenType font which includes almost all mathematical symbols included in the latest version of Unicode.

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