# Strict Conditional in LaTeX

I just had occasion to have to typeset Lewis’s strict conditional symbol <img src="http://plato.stanford.edu/archives/win2004/symbols/fishhook.gif" alt="- in LaTeX. It turns out it isn’t in the standard AMS fonts. Peter Smith’s LaTeX for Logicians to the rescue! There I found:

1. that the strict conditional symbol is in the fonts that are part of the txfonts and pxfonts packages, and
2. that there is a wonderful 110 page/3 MB comprehensive listing of all LaTeX symbols (by Scott Pakin).

Now it turns out that the point of txfonts and pxfonts is to give you output in Times Roman and Palatino fonts, respectively, with matching math and symbol fonts. That’s useful in itself–but if you happen to not want your document to be in Times or Palatino, you can still get \strictif by putting this in the preamble:

\DeclareSymbolFont{symbolsC}{U}{txsyc}{m}{n}
\DeclareMathSymbol{\strictif}{\mathrel}{symbolsC}{74}

## 6 thoughts on “Strict Conditional in LaTeX”

1. lumpy pea coat says:

Good to know!

2. Anonymous says:

That’s helpful! Is there a similar trick for typesetting the box arrow’ symbol that is sometimes used for the counterfactual conditional? I think it’s called \boxright’ in pxfonts/txfonts.

3. Richard Zach says:

Just look up the font and symbol declarations in txfonts.sty:\DeclareMathSymbol{\boxright}{\mathrel}{symbolsC}{128}

4. Peter Smith says:

I’ve added (with acknowledgement!) your code for using symbols extracted from txfonts to LaTeX for Logicians. Thanks for that!